From c07e8624d2f5e63395d951e19d26c831f935f811 Mon Sep 17 00:00:00 2001
From: TJ Saunders <tj@castaglia.org>
Date: Sun, 26 Sep 2021 14:43:38 -0700
Subject: [PATCH] Issue #1330: Implement OpenSSH "Encrypt-Then-MAC" (ETM)
 algorithm extensions.

---
 NEWS                                          |    1 +
 RELEASE_NOTES                                 |    3 +
 contrib/mod_sftp/cipher.c                     |   63 +-
 contrib/mod_sftp/crypto.c                     |   30 +-
 contrib/mod_sftp/mac.c                        |  117 +-
 contrib/mod_sftp/mac.h                        |   22 +-
 contrib/mod_sftp/packet.c                     |  315 +++--
 doc/contrib/mod_sftp.html                     |   13 +
 tests/t/lib/ProFTPD/Tests/Modules/mod_sftp.pm | 1021 +++++++++++++++++
 9 files changed, 1450 insertions(+), 135 deletions(-)

diff --git a/NEWS b/NEWS
index f087237e8d..05e54a0342 100644
--- a/NEWS
+++ b/NEWS
@@ -24,6 +24,7 @@
   added to mod_sftp.
 - Issue 1333 - Implement an LDAPConnectTimeout directive, to configure the
   timeout used when connecting to LDAP servers.
+- Issue 1330 - Implement OpenSSH "Encrypt-Then-MAC" (ETM) algorithm extensions.
 
 1.3.8rc2 - Released 29-Aug-2021
 --------------------------------
diff --git a/RELEASE_NOTES b/RELEASE_NOTES
index 08976a8956..b7087b3ab8 100644
--- a/RELEASE_NOTES
+++ b/RELEASE_NOTES
@@ -26,6 +26,9 @@ ChangeLog files.
     SFTPCiphers
       "aes128-gcm@openssh.com", "aes256-gcm@openssh.com" (Bug #3759)
 
+    SFTPDigests
+      "hmac-md5-etm@openssh.com", ... (Issue #1330)
+
     SFTPOptions NoHostkeyRotation
 
 
diff --git a/contrib/mod_sftp/cipher.c b/contrib/mod_sftp/cipher.c
index fd4b2541a7..496bbd06a2 100644
--- a/contrib/mod_sftp/cipher.c
+++ b/contrib/mod_sftp/cipher.c
@@ -479,7 +479,7 @@ int sftp_cipher_set_read_key(pool *p, const EVP_MD *hash, const BIGNUM *k,
   pctx = read_ctxs[read_cipher_idx];
 
   bufsz = buflen = SFTP_CIPHER_BUFSZ;
-  ptr = buf = sftp_msg_getbuf(p, bufsz);
+  ptr = buf = palloc(p, bufsz);
 
   /* Need to use SSH2-style format of K for the IV and key. */
   sftp_msg_write_mpint(&buf, &buflen, k);
@@ -626,38 +626,31 @@ int sftp_cipher_read_data(struct ssh2_packet *pkt, unsigned char *data,
 
       /* Allocate a buffer that's large enough. */
       bufsz = (data_len + read_blocksz - 1);
-      ptr = buf2 = palloc(pkt->pool, bufsz);
+      ptr = buf2 = pcalloc(pkt->pool, bufsz);
 
     } else {
       ptr = buf2 = *buf;
     }
 
-    if (pkt->packet_len == 0 &&
-        auth_len > 0) {
-      unsigned char prev_iv[1];
-
+    if (pkt->packet_len == 0) {
+      if (auth_len > 0) {
 #if defined(EVP_CTRL_GCM_IV_GEN)
-      /* Increment the IV. */
-      if (EVP_CIPHER_CTX_ctrl(pctx, EVP_CTRL_GCM_IV_GEN, 1, prev_iv) != 1) {
-        (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
-          "error incrementing %s IV data for client: %s", cipher->algo,
-          sftp_crypto_get_errors());
-        errno = EIO;
-        return -1;
-      }
-#endif
+        unsigned char prev_iv[1];
 
-      if (pkt->aad_len > 0 &&
-          pkt->aad == NULL) {
-        if (EVP_Cipher(pctx, NULL, data, pkt->aad_len) < 0) {
+        /* Increment the IV. */
+        if (EVP_CIPHER_CTX_ctrl(pctx, EVP_CTRL_GCM_IV_GEN, 1, prev_iv) != 1) {
           (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
-            "error setting %s AAD data for client: %s", cipher->algo,
+            "error incrementing %s IV data for client: %s", cipher->algo,
             sftp_crypto_get_errors());
           errno = EIO;
           return -1;
         }
+#endif
+      }
 
-        pkt->aad = palloc(pkt->pool, pkt->aad_len);
+      if (pkt->aad_len > 0 &&
+          pkt->aad == NULL) {
+        pkt->aad = pcalloc(pkt->pool, pkt->aad_len);
         memcpy(pkt->aad, data, pkt->aad_len);
         memcpy(ptr, data, pkt->aad_len);
 
@@ -668,6 +661,16 @@ int sftp_cipher_read_data(struct ssh2_packet *pkt, unsigned char *data,
         data += pkt->aad_len;
         data_len -= pkt->aad_len;
         output_buflen -= pkt->aad_len;
+
+        if (auth_len > 0) {
+          if (EVP_Cipher(pctx, NULL, pkt->aad, pkt->aad_len) < 0) {
+            (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
+              "error setting %s AAD data for client: %s", cipher->algo,
+              sftp_crypto_get_errors());
+            errno = EIO;
+            return -1;
+          }
+        }
       }
     }
 
@@ -819,7 +822,7 @@ int sftp_cipher_set_write_key(pool *p, const EVP_MD *hash, const BIGNUM *k,
   pctx = write_ctxs[write_cipher_idx];
 
   bufsz = buflen = SFTP_CIPHER_BUFSZ;
-  ptr = buf = sftp_msg_getbuf(p, bufsz);
+  ptr = buf = palloc(p, bufsz);
 
   /* Need to use SSH2-style format of K for the IV and key. */
   sftp_msg_write_mpint(&buf, &buflen, k);
@@ -964,15 +967,18 @@ int sftp_cipher_write_data(struct ssh2_packet *pkt, unsigned char *buf,
        * Encrypt-Then-MAC modes.
        */
       datasz -= pkt->aad_len;
+
+      /* And, for ETM modes, we may need a little more space. */
+      datasz += sftp_cipher_get_write_block_size();
     }
 
     datalen = datasz;
     ptr = data = palloc(pkt->pool, datasz);
 
     if (auth_len > 0) {
+#if defined(EVP_CTRL_GCM_IV_GEN)
       unsigned char prev_iv[1];
 
-#if defined(EVP_CTRL_GCM_IV_GEN)
       /* Increment the IV. */
       if (EVP_CIPHER_CTX_ctrl(pctx, EVP_CTRL_GCM_IV_GEN, 1, prev_iv) != 1) {
         (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
@@ -982,14 +988,17 @@ int sftp_cipher_write_data(struct ssh2_packet *pkt, unsigned char *buf,
         return -1;
       }
 #endif
+    }
 
-      if (pkt->aad_len > 0) {
-        uint32_t packet_len;
+    if (pkt->aad_len > 0 &&
+        pkt->aad == NULL) {
+      uint32_t packet_len;
 
-        packet_len = htonl(pkt->packet_len);
-        pkt->aad = palloc(pkt->pool, pkt->aad_len);
-        memcpy(pkt->aad, &packet_len, pkt->aad_len);
+      packet_len = htonl(pkt->packet_len);
+      pkt->aad = pcalloc(pkt->pool, pkt->aad_len);
+      memcpy(pkt->aad, &packet_len, pkt->aad_len);
 
+      if (auth_len > 0) {
         if (EVP_Cipher(pctx, NULL, pkt->aad, pkt->aad_len) < 0) {
           (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
             "error setting %s AAD (%lu bytes) for client: %s", cipher->algo,
diff --git a/contrib/mod_sftp/crypto.c b/contrib/mod_sftp/crypto.c
index 930b752e44..1ed1f4d476 100644
--- a/contrib/mod_sftp/crypto.c
+++ b/contrib/mod_sftp/crypto.c
@@ -169,20 +169,28 @@ static struct sftp_digest digests[] = {
    */
 #ifdef HAVE_SHA256_OPENSSL
   { "hmac-sha2-256",	"sha256",		EVP_sha256,	0, TRUE, TRUE },
+  { "hmac-sha2-256-etm@openssh.com", "sha256",	EVP_sha256,	0, TRUE, TRUE },
 #endif /* SHA256 support in OpenSSL */
 #ifdef HAVE_SHA512_OPENSSL
   { "hmac-sha2-512",	"sha512",		EVP_sha512,	0, TRUE, TRUE },
+  { "hmac-sha2-512-etm@openssh.com", "sha512",	EVP_sha512,	0, TRUE, TRUE },
 #endif /* SHA512 support in OpenSSL */
   { "hmac-sha1",	"sha1",		EVP_sha1,	0, 	TRUE, TRUE },
+  { "hmac-sha1-etm@openssh.com", "sha1",EVP_sha1,	0, 	TRUE, TRUE },
   { "hmac-sha1-96",	"sha1",		EVP_sha1,	12,	TRUE, TRUE },
+  { "hmac-sha1-96-etm@openssh.com", "sha1", EVP_sha1,	12, 	TRUE, TRUE },
   { "hmac-md5",		"md5",		EVP_md5,	0,	FALSE, FALSE },
+  { "hmac-md5-etm@openssh.com", "md5",	EVP_md5,	0, 	FALSE, TRUE },
   { "hmac-md5-96",	"md5",		EVP_md5,	12,	FALSE, FALSE },
+  { "hmac-md5-96-etm@openssh.com", "md5", EVP_md5,	12, 	FALSE, TRUE },
 #if !defined(OPENSSL_NO_RIPEMD)
   { "hmac-ripemd160",	"rmd160",	EVP_ripemd160,	0,	FALSE, FALSE },
 #endif /* !OPENSSL_NO_RIPEMD */
 #if OPENSSL_VERSION_NUMBER > 0x000907000L
   { "umac-64@openssh.com", NULL,	NULL,		8,	TRUE, FALSE },
+  { "umac-64-etm@openssh.com", NULL,	NULL,		8,	TRUE, FALSE },
   { "umac-128@openssh.com", NULL,	NULL,		16,	TRUE, FALSE },
+  { "umac-128-etm@openssh.com", NULL,	NULL,		16,	TRUE, FALSE },
 #endif /* OpenSSL-0.9.7 or later */
   { "none",		"null",		EVP_md_null,	0,	FALSE, TRUE },
   { NULL, NULL, NULL, 0, FALSE, FALSE }
@@ -1046,10 +1054,12 @@ const EVP_MD *sftp_crypto_get_digest(const char *name, uint32_t *mac_len) {
       const EVP_MD *digest = NULL;
 
 #if OPENSSL_VERSION_NUMBER > 0x000907000L
-      if (strncmp(name, "umac-64@openssh.com", 12) == 0) {
+      if (strcmp(name, "umac-64@openssh.com") == 0 ||
+          strcmp(name, "umac-64-etm@openssh.com") == 0) {
         digest = get_umac64_digest();
 
-      } else if (strncmp(name, "umac-128@openssh.com", 13) == 0) {
+      } else if (strcmp(name, "umac-128@openssh.com") == 0 ||
+                 strcmp(name, "umac-128-etm@openssh.com") == 0) {
         digest = get_umac128_digest();
 #else
       if (FALSE) {
@@ -1237,7 +1247,7 @@ const char *sftp_crypto_get_kexinit_digest_list(pool *p) {
           }
 #endif /* OPENSSL_FIPS */
 
-          if (strncmp(c->argv[i], "none", 5) != 0) {
+          if (strcmp(c->argv[i], "none") != 0) {
             if (digests[j].openssl_name != NULL &&
                 EVP_get_digestbyname(digests[j].openssl_name) != NULL) {
               res = pstrcat(p, res, *res ? "," : "",
@@ -1245,8 +1255,10 @@ const char *sftp_crypto_get_kexinit_digest_list(pool *p) {
 
             } else {
               /* The umac-64/umac-128 digests are special cases. */
-              if (strncmp(digests[j].name, "umac-64@openssh.com", 12) == 0 ||
-                  strncmp(digests[j].name, "umac-128@openssh.com", 13) == 0) {
+              if (strcmp(digests[j].name, "umac-64@openssh.com") == 0 ||
+                  strcmp(digests[j].name, "umac-64-etm@openssh.com") == 0 ||
+                  strcmp(digests[j].name, "umac-128@openssh.com") == 0 ||
+                  strcmp(digests[j].name, "umac-128-etm@openssh.com") == 0) {
                 res = pstrcat(p, res, *res ? "," : "",
                   pstrdup(p, digests[j].name), NULL);
 
@@ -1284,7 +1296,7 @@ const char *sftp_crypto_get_kexinit_digest_list(pool *p) {
           }
 #endif /* OPENSSL_FIPS */
 
-        if (strncmp(digests[i].name, "none", 5) != 0) {
+        if (strcmp(digests[i].name, "none") != 0) {
           if (digests[i].openssl_name != NULL &&
               EVP_get_digestbyname(digests[i].openssl_name) != NULL) {
             res = pstrcat(p, res, *res ? "," : "",
@@ -1292,8 +1304,10 @@ const char *sftp_crypto_get_kexinit_digest_list(pool *p) {
 
           } else {
             /* The umac-64/umac-128 digests are special cases. */
-            if (strncmp(digests[i].name, "umac-64@openssh.com", 12) == 0 ||
-                strncmp(digests[i].name, "umac-128@openssh.com", 13) == 0) {
+            if (strcmp(digests[i].name, "umac-64@openssh.com") == 0 ||
+                strcmp(digests[i].name, "umac-64-etm@openssh.com") == 0 ||
+                strcmp(digests[i].name, "umac-128@openssh.com") == 0 ||
+                strcmp(digests[i].name, "umac-128-etm@openssh.com") == 0) {
               res = pstrcat(p, res, *res ? "," : "",
                 pstrdup(p, digests[i].name), NULL);
 
diff --git a/contrib/mod_sftp/mac.c b/contrib/mod_sftp/mac.c
index fa3fbc0d84..3a40bcea47 100644
--- a/contrib/mod_sftp/mac.c
+++ b/contrib/mod_sftp/mac.c
@@ -38,6 +38,7 @@ struct sftp_mac {
   pool *pool;
   const char *algo;
   int algo_type;
+  int is_etm;
 
   const EVP_MD *digest;
 
@@ -66,15 +67,15 @@ struct sftp_mac {
  */
 
 static struct sftp_mac read_macs[] = {
-  { NULL, NULL, 0, NULL, NULL, 0, 0, 0 },
-  { NULL, NULL, 0, NULL, NULL, 0, 0, 0 }
+  { NULL, NULL, 0, FALSE, NULL, NULL, 0, 0, 0 },
+  { NULL, NULL, 0, FALSE, NULL, NULL, 0, 0, 0 }
 };
 static HMAC_CTX *hmac_read_ctxs[2];
 static struct umac_ctx *umac_read_ctxs[2];
 
 static struct sftp_mac write_macs[] = {
-  { NULL, NULL, 0, NULL, NULL, 0, 0, 0 },
-  { NULL, NULL, 0, NULL, NULL, 0, 0, 0 }
+  { NULL, NULL, 0, FALSE, NULL, NULL, 0, 0, 0 },
+  { NULL, NULL, 0, FALSE, NULL, NULL, 0, 0, 0 }
 };
 static HMAC_CTX *hmac_write_ctxs[2];
 static struct umac_ctx *umac_write_ctxs[2];
@@ -222,7 +223,7 @@ static int init_mac(pool *p, struct sftp_mac *mac, HMAC_CTX *hmac_ctx,
 }
 
 static int get_mac(struct ssh2_packet *pkt, struct sftp_mac *mac,
-    HMAC_CTX *hmac_ctx, struct umac_ctx *umac_ctx, int flags) {
+    HMAC_CTX *hmac_ctx, struct umac_ctx *umac_ctx, int etm_mac, int flags) {
   unsigned char *mac_data;
   unsigned char *buf, *ptr;
   uint32_t buflen, bufsz = 0, mac_len = 0;
@@ -231,14 +232,28 @@ static int get_mac(struct ssh2_packet *pkt, struct sftp_mac *mac,
     bufsz = (sizeof(uint32_t) * 2) + pkt->packet_len;
     mac_data = pcalloc(pkt->pool, EVP_MAX_MD_SIZE);
 
+    if (etm_mac == TRUE) {
+      bufsz += sftp_mac_get_block_size();
+    }
+
     buflen = bufsz;
-    ptr = buf = sftp_msg_getbuf(pkt->pool, bufsz);
+    ptr = buf = palloc(pkt->pool, bufsz);
 
     sftp_msg_write_int(&buf, &buflen, pkt->seqno);
     sftp_msg_write_int(&buf, &buflen, pkt->packet_len);
-    sftp_msg_write_byte(&buf, &buflen, pkt->padding_len);
+
+    if (etm_mac == FALSE) {
+      /* For Encrypt-Then-Mac modes, padding and its length will be part of
+       * the encrypted payload.
+       */
+      sftp_msg_write_byte(&buf, &buflen, pkt->padding_len);
+    }
+
     sftp_msg_write_data(&buf, &buflen, pkt->payload, pkt->payload_len, FALSE);
-    sftp_msg_write_data(&buf, &buflen, pkt->padding, pkt->padding_len, FALSE);
+
+    if (etm_mac == FALSE) {
+      sftp_msg_write_data(&buf, &buflen, pkt->padding, pkt->padding_len, FALSE);
+    }
 
 #if OPENSSL_VERSION_NUMBER > 0x000907000L
 # if OPENSSL_VERSION_NUMBER >= 0x10000001L
@@ -284,13 +299,27 @@ static int get_mac(struct ssh2_packet *pkt, struct sftp_mac *mac,
     bufsz = sizeof(uint32_t) + pkt->packet_len;
     mac_data = pcalloc(pkt->pool, EVP_MAX_MD_SIZE);
 
+    if (etm_mac == TRUE) {
+      bufsz += sftp_mac_get_block_size();
+    }
+
     buflen = bufsz;
-    ptr = buf = sftp_msg_getbuf(pkt->pool, bufsz);
+    ptr = buf = palloc(pkt->pool, bufsz);
 
     sftp_msg_write_int(&buf, &buflen, pkt->packet_len);
-    sftp_msg_write_byte(&buf, &buflen, pkt->padding_len);
+
+    if (etm_mac == FALSE) {
+      /* For Encrypt-Then-Mac modes, padding and its length will be part of
+       * the encrypted payload.
+       */
+      sftp_msg_write_byte(&buf, &buflen, pkt->padding_len);
+    }
+
     sftp_msg_write_data(&buf, &buflen, pkt->payload, pkt->payload_len, FALSE);
-    sftp_msg_write_data(&buf, &buflen, pkt->padding, pkt->padding_len, FALSE);
+
+    if (etm_mac == FALSE) {
+      sftp_msg_write_data(&buf, &buflen, pkt->padding, pkt->padding_len, FALSE);
+    }
 
     nonce_ptr = nonce;
     nonce_len = sizeof(nonce);
@@ -660,7 +689,17 @@ const char *sftp_mac_get_read_algo(void) {
   return NULL;
 }
 
+int sftp_mac_is_read_etm(void) {
+  if (read_macs[read_mac_idx].key) {
+    return read_macs[read_mac_idx].is_etm;
+  }
+
+  return FALSE;
+}
+
 int sftp_mac_set_read_algo(const char *algo) {
+  const char *etm_suffix;
+  size_t algo_len, etm_len;
   uint32_t mac_len;
   unsigned int idx = read_mac_idx;
 
@@ -706,11 +745,13 @@ int sftp_mac_set_read_algo(const char *algo) {
   pr_pool_tag(read_macs[idx].pool, "SFTP MAC read pool");
   read_macs[idx].algo = pstrdup(read_macs[idx].pool, algo);
 
-  if (strncmp(read_macs[idx].algo, "umac-64@openssh.com", 12) == 0) {
+  if (strcmp(read_macs[idx].algo, "umac-64@openssh.com") == 0 ||
+      strcmp(read_macs[idx].algo, "umac-64-etm@openssh.com") == 0) {
     read_macs[idx].algo_type = SFTP_MAC_ALGO_TYPE_UMAC64;
     umac_read_ctxs[idx] = umac_alloc();
 
-  } else if (strncmp(read_macs[idx].algo, "umac-128@openssh.com", 13) == 0) {
+  } else if (strcmp(read_macs[idx].algo, "umac-128@openssh.com") == 0 ||
+             strcmp(read_macs[idx].algo, "umac-128-etm@openssh.com") == 0) {
     read_macs[idx].algo_type = SFTP_MAC_ALGO_TYPE_UMAC128;
     umac_read_ctxs[idx] = umac128_alloc();
 
@@ -719,6 +760,15 @@ int sftp_mac_set_read_algo(const char *algo) {
   }
 
   read_macs[idx].mac_len = mac_len;
+
+  algo_len = strlen(algo);
+  etm_suffix = "-etm@openssh.com";
+  etm_len = strlen(etm_suffix);
+
+  if (pr_strnrstr(algo, algo_len, etm_suffix, etm_len, 0) == TRUE) {
+    read_macs[idx].is_etm = TRUE;
+  }
+
   return 0;
 }
 
@@ -745,7 +795,7 @@ int sftp_mac_set_read_key(pool *p, const EVP_MD *hash, const BIGNUM *k,
   umac_ctx = umac_read_ctxs[read_mac_idx];
 
   bufsz = buflen = SFTP_MAC_BUFSZ;
-  ptr = buf = sftp_msg_getbuf(p, bufsz);
+  ptr = buf = palloc(p, bufsz);
 
   /* Need to use SSH2-style format of K for the key. */
   sftp_msg_write_mpint(&buf, &buflen, k);
@@ -785,13 +835,15 @@ int sftp_mac_read_data(struct ssh2_packet *pkt) {
   struct sftp_mac *mac;
   HMAC_CTX *hmac_ctx;
   struct umac_ctx *umac_ctx;
-  int res;
+  int res, etm_mac = FALSE;
 
   /* For authenticated encryption ciphers, there is no separate MAC. */
   if (sftp_cipher_get_read_auth_size() > 0) {
     return 0;
   }
 
+  etm_mac = sftp_mac_is_read_etm();
+
   mac = &(read_macs[read_mac_idx]);
   hmac_ctx = hmac_read_ctxs[read_mac_idx];
   umac_ctx = umac_read_ctxs[read_mac_idx];
@@ -803,7 +855,7 @@ int sftp_mac_read_data(struct ssh2_packet *pkt) {
     return 0;
   }
 
-  res = get_mac(pkt, mac, hmac_ctx, umac_ctx, SFTP_MAC_FL_READ_MAC);
+  res = get_mac(pkt, mac, hmac_ctx, umac_ctx, etm_mac, SFTP_MAC_FL_READ_MAC);
   if (res < 0) {
     return -1;
   }
@@ -819,7 +871,17 @@ const char *sftp_mac_get_write_algo(void) {
   return NULL;
 }
 
+int sftp_mac_is_write_etm(void) {
+  if (write_macs[write_mac_idx].key) {
+    return write_macs[write_mac_idx].is_etm;
+  }
+
+  return FALSE;
+}
+
 int sftp_mac_set_write_algo(const char *algo) {
+  const char *etm_suffix;
+  size_t algo_len, etm_len;
   uint32_t mac_len;
   unsigned int idx = write_mac_idx;
 
@@ -865,11 +927,13 @@ int sftp_mac_set_write_algo(const char *algo) {
   pr_pool_tag(write_macs[idx].pool, "SFTP MAC write pool");
   write_macs[idx].algo = pstrdup(write_macs[idx].pool, algo);
 
-  if (strncmp(write_macs[idx].algo, "umac-64@openssh.com", 12) == 0) {
+  if (strcmp(write_macs[idx].algo, "umac-64@openssh.com") == 0 ||
+      strcmp(write_macs[idx].algo, "umac-64-etm@openssh.com") == 0) {
     write_macs[idx].algo_type = SFTP_MAC_ALGO_TYPE_UMAC64;
     umac_write_ctxs[idx] = umac_alloc();
 
-  } else if (strncmp(write_macs[idx].algo, "umac-128@openssh.com", 13) == 0) {
+  } else if (strcmp(write_macs[idx].algo, "umac-128@openssh.com") == 0 ||
+             strcmp(write_macs[idx].algo, "umac-128-etm@openssh.com") == 0) {
     write_macs[idx].algo_type = SFTP_MAC_ALGO_TYPE_UMAC128;
     umac_write_ctxs[idx] = umac128_alloc();
 
@@ -878,6 +942,15 @@ int sftp_mac_set_write_algo(const char *algo) {
   }
 
   write_macs[idx].mac_len = mac_len;
+
+  algo_len = strlen(algo);
+  etm_suffix = "-etm@openssh.com";
+  etm_len = strlen(etm_suffix);
+
+  if (pr_strnrstr(algo, algo_len, etm_suffix, etm_len, 0) == TRUE) {
+    write_macs[idx].is_etm = TRUE;
+  }
+
   return 0;
 }
 
@@ -903,7 +976,7 @@ int sftp_mac_set_write_key(pool *p, const EVP_MD *hash, const BIGNUM *k,
   umac_ctx = umac_write_ctxs[write_mac_idx];
 
   bufsz = buflen = SFTP_MAC_BUFSZ;
-  ptr = buf = sftp_msg_getbuf(p, bufsz);
+  ptr = buf = palloc(p, bufsz);
 
   /* Need to use SSH2-style format of K for the key. */
   sftp_msg_write_mpint(&buf, &buflen, k);
@@ -935,13 +1008,15 @@ int sftp_mac_write_data(struct ssh2_packet *pkt) {
   struct sftp_mac *mac;
   HMAC_CTX *hmac_ctx;
   struct umac_ctx *umac_ctx;
-  int res;
+  int res, etm_mac = FALSE;
 
   /* For authenticated encryption ciphers, there is no separate MAC. */
   if (sftp_cipher_get_write_auth_size() > 0) {
     return 0;
   }
 
+  etm_mac = sftp_mac_is_write_etm();
+
   mac = &(write_macs[write_mac_idx]);
   hmac_ctx = hmac_write_ctxs[write_mac_idx];
   umac_ctx = umac_write_ctxs[write_mac_idx];
@@ -953,7 +1028,7 @@ int sftp_mac_write_data(struct ssh2_packet *pkt) {
     return 0;
   }
 
-  res = get_mac(pkt, mac, hmac_ctx, umac_ctx, SFTP_MAC_FL_WRITE_MAC);
+  res = get_mac(pkt, mac, hmac_ctx, umac_ctx, etm_mac, SFTP_MAC_FL_WRITE_MAC);
   if (res < 0) {
     return -1;
   }
diff --git a/contrib/mod_sftp/mac.h b/contrib/mod_sftp/mac.h
index 40dd92e09a..229d391ef6 100644
--- a/contrib/mod_sftp/mac.h
+++ b/contrib/mod_sftp/mac.h
@@ -1,6 +1,6 @@
 /*
  * ProFTPD - mod_sftp MAC mgmt
- * Copyright (c) 2008-2017 TJ Saunders
+ * Copyright (c) 2008-2021 TJ Saunders
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -35,18 +35,20 @@ int sftp_mac_free(void);
  * has been negotiated yet.
  */
 size_t sftp_mac_get_block_size(void);
-void sftp_mac_set_block_size(size_t);
+void sftp_mac_set_block_size(size_t blocksz);
 
 const char *sftp_mac_get_read_algo(void);
-int sftp_mac_set_read_algo(const char *);
-int sftp_mac_set_read_key(pool *, const EVP_MD *, const BIGNUM *, const char *,
-  uint32_t, int);
-int sftp_mac_read_data(struct ssh2_packet *);
+int sftp_mac_is_read_etm(void);
+int sftp_mac_set_read_algo(const char *algo);
+int sftp_mac_set_read_key(pool *p, const EVP_MD *md, const BIGNUM *k,
+  const char *h, uint32_t hlen, int role);
+int sftp_mac_read_data(struct ssh2_packet *pkt);
 
 const char *sftp_mac_get_write_algo(void);
-int sftp_mac_set_write_algo(const char *);
-int sftp_mac_set_write_key(pool *, const EVP_MD *, const BIGNUM *, const char *,
-  uint32_t, int);
-int sftp_mac_write_data(struct ssh2_packet *);
+int sftp_mac_is_write_etm(void);
+int sftp_mac_set_write_algo(const char *algo);
+int sftp_mac_set_write_key(pool *p, const EVP_MD *md, const BIGNUM *k,
+  const char *h, uint32_t hlen, int role);
+int sftp_mac_write_data(struct ssh2_packet *pkt);
 
 #endif /* MOD_SFTP_MAC_H */
diff --git a/contrib/mod_sftp/packet.c b/contrib/mod_sftp/packet.c
index e38ca337c4..82dc95e297 100644
--- a/contrib/mod_sftp/packet.c
+++ b/contrib/mod_sftp/packet.c
@@ -478,7 +478,8 @@ static void read_packet_discard(int sockfd) {
 }
 
 static int read_packet_len(int sockfd, struct ssh2_packet *pkt,
-    unsigned char *buf, size_t *offset, size_t *buflen, size_t bufsz) {
+    unsigned char *buf, size_t *offset, size_t *buflen, size_t bufsz,
+    int etm_mac) {
   uint32_t packet_len = 0, len = 0;
   size_t readsz;
   int res;
@@ -492,10 +493,16 @@ static int read_packet_len(int sockfd, struct ssh2_packet *pkt,
    */
 
   if (pkt->aad_len > 0) {
-    /* If we are dealing with an authenticated encryption algorithm, read
-     * enough to include the AAD and the first block.
+    /* If we are dealing with an authenticated encryption algorithm, or an
+     * ETM mode, read enough to include the AAD.  For ETM modes, leave the
+     * first block for later.
      */
-    readsz += pkt->aad_len;
+    if (etm_mac == TRUE) {
+      readsz = pkt->aad_len;
+
+    } else {
+      readsz += pkt->aad_len;
+    }
   }
 
   res = sftp_ssh2_packet_sock_read(sockfd, buf, readsz, 0);
@@ -547,15 +554,31 @@ static int read_packet_padding_len(int sockfd, struct ssh2_packet *pkt,
 }
 
 static int read_packet_payload(int sockfd, struct ssh2_packet *pkt,
-    unsigned char *buf, size_t *offset, size_t *buflen, size_t bufsz) {
+    unsigned char *buf, size_t *offset, size_t *buflen, size_t bufsz,
+    int etm_mac) {
   unsigned char *ptr = NULL;
   int res;
-  uint32_t payload_len = pkt->payload_len, padding_len = pkt->padding_len,
-    auth_len = 0, data_len, len = 0;
+  uint32_t payload_len = pkt->payload_len, padding_len = 0, auth_len = 0,
+    data_len, len = 0;
+
+  /* For authenticated encryption or ETM modes, we will NOT have the
+   * pkt->padding_len field yet.
+   *
+   * For authenticated encryption, we need to read in the first block, then
+   * decrypt it, to find the padding.
+   *
+   * For ETM, we only want to find the payload and padding AFTER we've read
+   * the entire (encrypted) payload, MAC'd it, THEN decrypt it.
+   */
+
+  if (pkt->padding_len > 0) {
+    padding_len = pkt->padding_len;
+  }
 
   auth_len = sftp_cipher_get_read_auth_size();
 
-  if (payload_len + padding_len + auth_len == 0) {
+  if (payload_len + padding_len + auth_len == 0 &&
+      etm_mac == FALSE) {
     return 0;
   }
 
@@ -602,14 +625,20 @@ static int read_packet_payload(int sockfd, struct ssh2_packet *pkt,
     }
   }
 
-  /* The padding length is required to be greater than zero. */
-  pkt->padding = pcalloc(pkt->pool, padding_len);
+  /* The padding length is required to be greater than zero.  However, we may
+   * not know the padding length yet, as for authenticated encryption or ETM
+   * modes.
+   */
+  if (padding_len > 0) {
+    pkt->padding = pcalloc(pkt->pool, padding_len);
+  }
 
   /* If there's data in the buffer we received, it's probably already part
    * of the padding, unencrypted.  That will leave the remaining padding
    * data, if any, to be read in and decrypted.
    */
-  if (*buflen > 0) {
+  if (*buflen > 0 &&
+      padding_len > 0) {
     if (*buflen < padding_len) {
       memmove(pkt->padding, buf + *offset, *buflen);
 
@@ -627,7 +656,13 @@ static int read_packet_payload(int sockfd, struct ssh2_packet *pkt,
     }
   }
 
-  data_len = payload_len + padding_len + auth_len;
+  if (etm_mac == TRUE) {
+    data_len = pkt->packet_len;
+
+  } else {
+    data_len = payload_len + padding_len + auth_len;
+  }
+
   if (data_len == 0) {
     return 0;
   }
@@ -644,19 +679,30 @@ static int read_packet_payload(int sockfd, struct ssh2_packet *pkt,
   if (res < 0) {
     return res;
   }
- 
+
   len = res;
-  if (sftp_cipher_read_data(pkt, buf + *offset, data_len, &ptr, &len) < 0) {
-    return -1;
-  }
 
-  if (payload_len > 0) {
-    memmove(pkt->payload + (pkt->payload_len - payload_len), ptr,
-      payload_len);
+  /* For ETM modes, we do NOT want to decrypt the data yet; we need to read/
+   * compare MACs first.
+   */
+
+  if (etm_mac == TRUE) {
+    *buflen = res;
+
+  } else {
+    if (sftp_cipher_read_data(pkt, buf + *offset, data_len, &ptr, &len) < 0) {
+      return -1;
+    }
+
+    if (payload_len > 0) {
+      memmove(pkt->payload + (pkt->payload_len - payload_len), ptr,
+        payload_len);
+    }
+
+    memmove(pkt->padding + (pkt->padding_len - padding_len), ptr + payload_len,
+      padding_len);
   }
 
-  memmove(pkt->padding + (pkt->padding_len - padding_len), ptr + payload_len,
-    padding_len);
   return 0;
 }
 
@@ -674,7 +720,7 @@ static int read_packet_mac(int sockfd, struct ssh2_packet *pkt,
     return res;
   }
 
-  pkt->mac = palloc(pkt->pool, pkt->mac_len);
+  pkt->mac = pcalloc(pkt->pool, pkt->mac_len);
   memmove(pkt->mac, buf, res);
 
   return 0;
@@ -857,6 +903,7 @@ int sftp_ssh2_packet_set_client_alive(unsigned int max, unsigned int interval) {
 int sftp_ssh2_packet_read(int sockfd, struct ssh2_packet *pkt) {
   unsigned char buf[SFTP_MAX_PACKET_LEN];
   size_t buflen, bufsz = SFTP_MAX_PACKET_LEN, offset = 0, auth_len = 0;
+  int etm_mac = FALSE;
 
   pr_session_set_idle();
 
@@ -868,6 +915,14 @@ int sftp_ssh2_packet_read(int sockfd, struct ssh2_packet *pkt) {
     pkt->aad_len = sizeof(uint32_t);
   }
 
+  etm_mac = sftp_mac_is_read_etm();
+  if (etm_mac == TRUE) {
+    /* ETM modes do not encrypt the packet length, and instead use it as
+     * Additional Authenticated Data (AAD).
+     */
+    pkt->aad_len = sizeof(uint32_t);
+  }
+
   while (TRUE) {
     uint32_t encrypted_datasz, req_blocksz;
     int res;
@@ -881,7 +936,8 @@ int sftp_ssh2_packet_read(int sockfd, struct ssh2_packet *pkt) {
     buflen = 0;
     memset(buf, 0, sizeof(buf));
 
-    if (read_packet_len(sockfd, pkt, buf, &offset, &buflen, bufsz) < 0) {
+    if (read_packet_len(sockfd, pkt, buf, &offset, &buflen, bufsz,
+        etm_mac) < 0) {
       (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
         "no data to be read from socket %d", sockfd);
       return -1;
@@ -904,18 +960,20 @@ int sftp_ssh2_packet_read(int sockfd, struct ssh2_packet *pkt) {
      * Thus that particular check is omitted.
      */
 
-    if (read_packet_padding_len(sockfd, pkt, buf, &offset, &buflen,
-        bufsz) < 0) {
-      (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
-        "no data to be read from socket %d", sockfd);
-      read_packet_discard(sockfd);
-      return -1;
-    }
+    if (etm_mac == FALSE) {
+      if (read_packet_padding_len(sockfd, pkt, buf, &offset, &buflen,
+          bufsz) < 0) {
+        (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
+          "no data to be read from socket %d", sockfd);
+        read_packet_discard(sockfd);
+        return -1;
+      }
 
-    pr_trace_msg(trace_channel, 20, "SSH2 packet padding len = %u bytes",
-      (unsigned int) pkt->padding_len);
+      pr_trace_msg(trace_channel, 20, "SSH2 packet padding len = %u bytes",
+        (unsigned int) pkt->padding_len);
 
-    pkt->payload_len = (pkt->packet_len - pkt->padding_len - 1);
+      pkt->payload_len = (pkt->packet_len - pkt->padding_len - 1);
+    }
 
     pr_trace_msg(trace_channel, 20, "SSH2 packet payload len = %lu bytes",
       (unsigned long) pkt->payload_len);
@@ -923,38 +981,108 @@ int sftp_ssh2_packet_read(int sockfd, struct ssh2_packet *pkt) {
     /* Read both payload and padding, since we may need to have both before
      * decrypting the data.
      */
-    if (read_packet_payload(sockfd, pkt, buf, &offset, &buflen, bufsz) < 0) {
+    if (read_packet_payload(sockfd, pkt, buf, &offset, &buflen, bufsz,
+        etm_mac) < 0) {
       (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
         "unable to read payload from socket %d", sockfd);
       read_packet_discard(sockfd);
       return -1;
     }
 
-    memset(buf, 0, sizeof(buf));
     pkt->mac_len = sftp_mac_get_block_size();
-
     pr_trace_msg(trace_channel, 20, "SSH2 packet MAC len = %lu bytes",
       (unsigned long) pkt->mac_len);
 
-    if (read_packet_mac(sockfd, pkt, buf) < 0) {
-      (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
-        "unable to read MAC from socket %d", sockfd);
-      read_packet_discard(sockfd);
-      return -1;
-    }
+    if (etm_mac == TRUE) {
+      unsigned char *buf2;
+      size_t buflen2, bufsz2;
 
-    pkt->seqno = packet_client_seqno;
+      bufsz2 = buflen2 = pkt->mac_len;
+      buf2 = pcalloc(pkt->pool, bufsz2);
 
-    if (sftp_mac_read_data(pkt) < 0) {
-      (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
-        "unable to verify MAC on packet from socket %d", sockfd);
+      /* The MAC routines assume the presence of the necessary data in
+       * pkt->payload, so we temporarily put our encrypted packet data there.
+       */
+      pkt->payload = buf;
+      pkt->payload_len = buflen;
+
+      pkt->seqno = packet_client_seqno;
+
+      if (read_packet_mac(sockfd, pkt, buf2) < 0) {
+        (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
+          "unable to read MAC from socket %d", sockfd);
+        read_packet_discard(sockfd);
+        return -1;
+      }
 
-      /* In order to further mitigate CPNI-957037, we will read in a
-       * random amount of more data from the network before closing
-       * the connection.
+      if (sftp_mac_read_data(pkt) < 0) {
+        (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
+          "unable to verify MAC on packet from socket %d", sockfd);
+
+        /* In order to further mitigate CPNI-957037, we will read in a
+         * random amount of more data from the network before closing
+         * the connection.
+         */
+        read_packet_discard(sockfd);
+        return -1;
+      }
+
+      /* Now we can decrypt the payload; `buf/buflen` are the encrypted
+       * packet from read_packet_payload().
        */
-      read_packet_discard(sockfd);
-      return -1;
+      bufsz2 = buflen2 = SFTP_MAX_PACKET_LEN;
+      buf2 = pcalloc(pkt->pool, bufsz2);
+
+      if (sftp_cipher_read_data(pkt, buf, buflen, &buf2,
+          (uint32_t *) &buflen2) < 0) {
+        return -1;
+      }
+
+      offset = 0;
+
+      if (read_packet_padding_len(sockfd, pkt, buf2, &offset, &buflen2,
+          bufsz2) < 0) {
+        (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
+          "no data to be read from socket %d", sockfd);
+        read_packet_discard(sockfd);
+        return -1;
+      }
+
+      pr_trace_msg(trace_channel, 20, "SSH2 packet padding len = %u bytes",
+        (unsigned int) pkt->padding_len);
+
+      pkt->payload_len = (pkt->packet_len - pkt->padding_len - 1);
+      if (pkt->payload_len > 0) {
+        pkt->payload = pcalloc(pkt->pool, pkt->payload_len);
+        memmove(pkt->payload, buf2 + offset, pkt->payload_len);
+      }
+
+      pkt->padding = pcalloc(pkt->pool, pkt->padding_len);
+      memmove(pkt->padding, buf2 + offset + pkt->payload_len, pkt->padding_len);
+
+    } else {
+      memset(buf, 0, sizeof(buf));
+
+      if (read_packet_mac(sockfd, pkt, buf) < 0) {
+        (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
+          "unable to read MAC from socket %d", sockfd);
+        read_packet_discard(sockfd);
+        return -1;
+      }
+
+      pkt->seqno = packet_client_seqno;
+
+      if (sftp_mac_read_data(pkt) < 0) {
+        (void) pr_log_writefile(sftp_logfd, MOD_SFTP_VERSION,
+          "unable to verify MAC on packet from socket %d", sockfd);
+
+        /* In order to further mitigate CPNI-957037, we will read in a
+         * random amount of more data from the network before closing
+         * the connection.
+         */
+        read_packet_discard(sockfd);
+        return -1;
+      }
     }
 
     /* Now that the MAC check has passed, we can do sanity checks based
@@ -1145,7 +1273,7 @@ int sftp_ssh2_packet_send(int sockfd, struct ssh2_packet *pkt) {
   unsigned char buf[SFTP_MAX_PACKET_LEN * 2], msg_type;
   size_t buflen = 0, bufsz = SFTP_MAX_PACKET_LEN;
   uint32_t packet_len = 0, auth_len = 0;
-  int res, write_len = 0, block_alarms = FALSE;
+  int res, write_len = 0, block_alarms = FALSE, etm_mac = FALSE;
 
   /* No interruptions, please.  If, for example, we are interrupted here
    * by the SFTPRekey timer, that timer will cause this same function to
@@ -1167,6 +1295,16 @@ int sftp_ssh2_packet_send(int sockfd, struct ssh2_packet *pkt) {
      * and instead use it as Additional Authenticated Data (AAD).
      */
     pkt->aad_len = sizeof(uint32_t);
+    pkt->aad = NULL;
+  }
+
+  etm_mac = sftp_mac_is_write_etm();
+  if (etm_mac == TRUE) {
+    /* Encrypt-Then-Mac modes do not encrypt the packet length; treat it
+     * as Additional Authenticated Data (AAD).
+     */
+    pkt->aad_len = sizeof(uint32_t);
+    pkt->aad = NULL;
   }
 
   /* Clear the iovec array before sending the data, if possible. */
@@ -1182,6 +1320,7 @@ int sftp_ssh2_packet_send(int sockfd, struct ssh2_packet *pkt) {
     if (block_alarms == TRUE) {
       pr_alarms_unblock();
     }
+
     errno = xerrno;
     return -1;
   }
@@ -1192,6 +1331,7 @@ int sftp_ssh2_packet_send(int sockfd, struct ssh2_packet *pkt) {
     if (block_alarms == TRUE) {
       pr_alarms_unblock();
     }
+
     errno = xerrno;
     return -1;
   }
@@ -1202,27 +1342,60 @@ int sftp_ssh2_packet_send(int sockfd, struct ssh2_packet *pkt) {
 
   pkt->seqno = packet_server_seqno;
 
-  if (sftp_mac_write_data(pkt) < 0) {
-    int xerrno = errno;
+  memset(buf, 0, sizeof(buf));
+  buflen = bufsz;
 
-    if (block_alarms == TRUE) {
-      pr_alarms_unblock();
+  if (etm_mac == TRUE) {
+    if (sftp_cipher_write_data(pkt, buf, &buflen) < 0) {
+      int xerrno = errno;
+
+      if (block_alarms == TRUE) {
+        pr_alarms_unblock();
+      }
+
+      errno = xerrno;
+      return -1;
     }
-    errno = xerrno;
-    return -1;
-  }
 
-  memset(buf, 0, sizeof(buf));
-  buflen = bufsz;
+    /* Once we have the encrypted data, overwrite the plaintext packet payload
+     * with it, so that the MAC is calculated from the encrypted data.
+     */
+    pkt->payload = buf;
+    pkt->payload_len = buflen;
 
-  if (sftp_cipher_write_data(pkt, buf, &buflen) < 0) {
-    int xerrno = errno;
+    if (sftp_mac_write_data(pkt) < 0) {
+      int xerrno = errno;
 
-    if (block_alarms == TRUE) {
-      pr_alarms_unblock();
+      if (block_alarms == TRUE) {
+        pr_alarms_unblock();
+      }
+
+      errno = xerrno;
+      return -1;
+    }
+
+  } else {
+    if (sftp_mac_write_data(pkt) < 0) {
+      int xerrno = errno;
+
+      if (block_alarms == TRUE) {
+        pr_alarms_unblock();
+      }
+
+      errno = xerrno;
+      return -1;
+    }
+
+    if (sftp_cipher_write_data(pkt, buf, &buflen) < 0) {
+      int xerrno = errno;
+
+      if (block_alarms == TRUE) {
+        pr_alarms_unblock();
+      }
+
+      errno = xerrno;
+      return -1;
     }
-    errno = xerrno;
-    return -1;
   }
 
   if (buflen > 0) {
@@ -1313,6 +1486,7 @@ int sftp_ssh2_packet_send(int sockfd, struct ssh2_packet *pkt) {
     if (block_alarms == TRUE) {
       pr_alarms_unblock();
     }
+
     errno = xerrno;
     return -1;
   }
@@ -1362,6 +1536,7 @@ int sftp_ssh2_packet_send(int sockfd, struct ssh2_packet *pkt) {
     if (block_alarms == TRUE) {
       pr_alarms_unblock();
     }
+
     errno = xerrno;
     return -1;
   }
@@ -1784,15 +1959,17 @@ int sftp_ssh2_packet_rekey_reset(void) {
   if (rekey_client_seqno > 0) {
     rekey_client_seqno = packet_client_seqno + SFTP_PACKET_CLIENT_REKEY_SEQNO_LIMIT;
 
-    if (rekey_client_seqno == 0)
+    if (rekey_client_seqno == 0) {
       rekey_client_seqno++;
+    }
   }
 
   if (rekey_server_seqno > 0) {
     rekey_server_seqno = packet_client_seqno + SFTP_PACKET_SERVER_REKEY_SEQNO_LIMIT;
 
-    if (rekey_server_seqno == 0)
+    if (rekey_server_seqno == 0) {
       rekey_server_seqno++;
+    }
   }
 
   return 0;
diff --git a/doc/contrib/mod_sftp.html b/doc/contrib/mod_sftp.html
index ca8d5cfe7d..a33ef8ae03 100644
--- a/doc/contrib/mod_sftp.html
+++ b/doc/contrib/mod_sftp.html
@@ -611,11 +611,17 @@ <h3><a name="SFTPDigests">SFTPDigests</a></h3>
 of supported MAC algorithms is:
 <ul>
   <li>hmac-sha2-256
+  <li>hmac-sha2-256-etm@openssh.com
   <li>hmac-sha2-512
+  <li>hmac-sha2-512-etm@openssh.com
   <li>hmac-sha1
+  <li>hmac-sha1-etm@openssh.com
   <li>hmac-sha1-96
+  <li>hmac-sha1-96-etm@openssh.com
   <li>umac-64@openssh.com
+  <li>umac-64-etm@openssh.com
   <li>umac-128@openssh.com
+  <li>umac-128-etm@openssh.com
 </ul>
 By default, all of the above MAC algorithms are presented to the client,
 in the above order, during the key exchange.  <b>Note</b> that some algorithms
@@ -628,6 +634,7 @@ <h3><a name="SFTPDigests">SFTPDigests</a></h3>
 configured via <code>SFTPDigests</code> to be available for use by clients:
 <ul>
   <li>hmac-md5
+  <li>hmac-md5-etm@openssh.com
   <li>hmac-md5-96
   <li>hmac-ripemd160
 </ul>
@@ -646,14 +653,20 @@ <h3><a name="SFTPDigests">SFTPDigests</a></h3>
 by default are:
 <ul>
   <li>hmac-md5
+  <li>hmac-md5-etm@openssh.com
   <li>hmac-sha1
+  <li>hmac-sha1-etm@openssh.com
   <li>hmac-sha2-256
+  <li>hmac-sha2-256-etm@openssh.com
   <li>hmac-sha2-512
+  <li>hmac-sha2-512-etm@openssh.com
   <li>hmac-ripemd160
   <li>hmac-sha1-96
   <li>hmac-md5-96
   <li>umac-64@openssh.com
+  <li>umac-64-etm@openssh.com
   <li>umac-128@openssh.com
+  <li>umac-128-etm@openssh.com
 </ul>
 Thus if you wanted to configure <code>mod_sftp</code> to present the same
 MAC algorithms as OpenSSH, you would use:
diff --git a/tests/t/lib/ProFTPD/Tests/Modules/mod_sftp.pm b/tests/t/lib/ProFTPD/Tests/Modules/mod_sftp.pm
index 452f824d7c..5e1da7e0f2 100644
--- a/tests/t/lib/ProFTPD/Tests/Modules/mod_sftp.pm
+++ b/tests/t/lib/ProFTPD/Tests/Modules/mod_sftp.pm
@@ -332,6 +332,36 @@ my $TESTS = {
     test_class => [qw(bug forking ssh2)],
   },
 
+  ssh2_ext_mac_hmac_md5_etm_openssh => {
+    order => ++$order,
+    test_class => [qw(forking ssh2)],
+  },
+
+  ssh2_ext_mac_hmac_sha1_etm_openssh => {
+    order => ++$order,
+    test_class => [qw(forking ssh2)],
+  },
+
+  ssh2_ext_mac_hmac_sha256_etm_openssh => {
+    order => ++$order,
+    test_class => [qw(forking ssh2)],
+  },
+
+  ssh2_ext_mac_hmac_sha512_etm_openssh => {
+    order => ++$order,
+    test_class => [qw(forking ssh2)],
+  },
+
+  ssh2_ext_mac_umac_64_etm_openssh => {
+    order => ++$order,
+    test_class => [qw(forking ssh2)],
+  },
+
+  ssh2_ext_mac_umac_128_etm_openssh => {
+    order => ++$order,
+    test_class => [qw(forking ssh2)],
+  },
+
   ssh2_compress_c2s_none => {
     order => ++$order,
     test_class => [qw(forking ssh2)],
@@ -11665,6 +11695,997 @@ EOC
   unlink($log_file);
 }
 
+sub ssh2_ext_mac_hmac_md5_etm_openssh {
+  my $self = shift;
+  my $tmpdir = $self->{tmpdir};
+  my $setup = test_setup($tmpdir, 'sftp');
+
+  my $rsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_rsa_key');
+  my $dsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_dsa_key');
+
+  my $rsa_priv_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key');
+  my $rsa_pub_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key.pub');
+  my $rsa_rfc4716_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/authorized_rsa_keys');
+
+  my $authorized_keys = File::Spec->rel2abs("$tmpdir/.authorized_keys");
+  unless (copy($rsa_rfc4716_key, $authorized_keys)) {
+    die("Can't copy $rsa_rfc4716_key to $authorized_keys: $!");
+  }
+
+  my $batch_file = File::Spec->rel2abs("$tmpdir/sftp-batch.conf");
+  if (open(my $fh, "> $batch_file")) {
+    print $fh "ls -al\n";
+
+    unless (close($fh)) {
+      die("Can't write $batch_file: $!");
+    }
+
+  } else {
+    die("Can't open $batch_file: $!");
+  }
+
+  my $config = {
+    PidFile => $setup->{pid_file},
+    ScoreboardFile => $setup->{scoreboard_file},
+    SystemLog => $setup->{log_file},
+    TraceLog => $setup->{log_file},
+    Trace => 'DEFAULT:10 lock:0 scoreboard:0 ssh2:30 sftp:30',
+
+    AuthUserFile => $setup->{auth_user_file},
+    AuthGroupFile => $setup->{auth_group_file},
+
+    IfModules => {
+      'mod_delay.c' => {
+        DelayEngine => 'off',
+      },
+
+      'mod_sftp.c' => [
+        "SFTPEngine on",
+        "SFTPLog $setup->{log_file}",
+        "SFTPHostKey $rsa_host_key",
+        "SFTPHostKey $dsa_host_key",
+        "SFTPAuthorizedUserKeys file:~/.authorized_keys",
+        'SFTPDigests hmac-md5-etm@openssh.com',
+      ],
+    },
+  };
+
+  my ($port, $config_user, $config_group) = config_write($setup->{config_file},
+    $config);
+
+  # Open pipes, for use between the parent and child processes.  Specifically,
+  # the child will indicate when it's done with its test by writing a message
+  # to the parent.
+  my ($rfh, $wfh);
+  unless (pipe($rfh, $wfh)) {
+    die("Can't open pipe: $!");
+  }
+
+  my $ex;
+
+  # Fork child
+  $self->handle_sigchld();
+  defined(my $pid = fork()) or die("Can't fork: $!");
+  if ($pid) {
+    eval {
+      # Allow server startup
+      sleep(1);
+
+      my $sftp = '/Users/tj/local/openssh-7.9p1/bin/sftp';
+
+      my @cmd = (
+        $sftp,
+        '-oBatchMode=yes',
+        '-oCheckHostIP=no',
+        '-oCompression=yes',
+        '-oMACs=hmac-md5-etm@openssh.com',
+        "-oPort=$port",
+        "-oIdentityFile=$rsa_priv_key",
+        '-oPubkeyAuthentication=yes',
+        '-oStrictHostKeyChecking=no',
+        '-vvv',
+        '-b',
+        $batch_file,
+        "$setup->{user}\@127.0.0.1",
+      );
+
+      my $sftp_rh = IO::Handle->new();
+      my $sftp_wh = IO::Handle->new();
+      my $sftp_eh = IO::Handle->new();
+
+      $sftp_wh->autoflush(1);
+
+      local $SIG{CHLD} = 'DEFAULT';
+
+      # Make sure that the perms on the priv key are what OpenSSH wants
+      unless (chmod(0400, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0400: $!");
+      }
+
+      if ($ENV{TEST_VERBOSE}) {
+        print STDERR "Executing: ", join(' ', @cmd), "\n";
+      }
+
+      my $sftp_pid = open3($sftp_wh, $sftp_rh, $sftp_eh, @cmd);
+      waitpid($sftp_pid, 0);
+      my $exit_status = $?;
+
+      # Restore the perms on the priv key
+      unless (chmod(0644, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0644: $!");
+      }
+
+      my ($res, $errstr);
+      if ($exit_status >> 8 == 0) {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 0;
+
+      } else {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 1;
+      }
+
+      unless ($res == 0) {
+        die("Can't list files on server: $errstr");
+      }
+    };
+    if ($@) {
+      $ex = $@;
+    }
+
+    $wfh->print("done\n");
+    $wfh->flush();
+
+  } else {
+    eval { server_wait($setup->{config_file}, $rfh) };
+    if ($@) {
+      warn($@);
+      exit 1;
+    }
+
+    exit 0;
+  }
+
+  # Stop server
+  server_stop($setup->{pid_file});
+  $self->assert_child_ok($pid);
+
+  test_cleanup($setup->{log_file}, $ex);
+}
+
+sub ssh2_ext_mac_hmac_sha1_etm_openssh {
+  my $self = shift;
+  my $tmpdir = $self->{tmpdir};
+  my $setup = test_setup($tmpdir, 'sftp');
+
+  my $rsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_rsa_key');
+  my $dsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_dsa_key');
+
+  my $rsa_priv_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key');
+  my $rsa_pub_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key.pub');
+  my $rsa_rfc4716_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/authorized_rsa_keys');
+
+  my $authorized_keys = File::Spec->rel2abs("$tmpdir/.authorized_keys");
+  unless (copy($rsa_rfc4716_key, $authorized_keys)) {
+    die("Can't copy $rsa_rfc4716_key to $authorized_keys: $!");
+  }
+
+  my $batch_file = File::Spec->rel2abs("$tmpdir/sftp-batch.conf");
+  if (open(my $fh, "> $batch_file")) {
+    print $fh "ls -al\n";
+
+    unless (close($fh)) {
+      die("Can't write $batch_file: $!");
+    }
+
+  } else {
+    die("Can't open $batch_file: $!");
+  }
+
+  my $config = {
+    PidFile => $setup->{pid_file},
+    ScoreboardFile => $setup->{scoreboard_file},
+    SystemLog => $setup->{log_file},
+    TraceLog => $setup->{log_file},
+    Trace => 'DEFAULT:10 lock:0 scoreboard:0 ssh2:30 sftp:30',
+
+    AuthUserFile => $setup->{auth_user_file},
+    AuthGroupFile => $setup->{auth_group_file},
+
+    IfModules => {
+      'mod_delay.c' => {
+        DelayEngine => 'off',
+      },
+
+      'mod_sftp.c' => [
+        "SFTPEngine on",
+        "SFTPLog $setup->{log_file}",
+        "SFTPHostKey $rsa_host_key",
+        "SFTPHostKey $dsa_host_key",
+        "SFTPAuthorizedUserKeys file:~/.authorized_keys",
+        'SFTPDigests hmac-sha1-etm@openssh.com',
+      ],
+    },
+  };
+
+  my ($port, $config_user, $config_group) = config_write($setup->{config_file},
+    $config);
+
+  # Open pipes, for use between the parent and child processes.  Specifically,
+  # the child will indicate when it's done with its test by writing a message
+  # to the parent.
+  my ($rfh, $wfh);
+  unless (pipe($rfh, $wfh)) {
+    die("Can't open pipe: $!");
+  }
+
+  my $ex;
+
+  # Fork child
+  $self->handle_sigchld();
+  defined(my $pid = fork()) or die("Can't fork: $!");
+  if ($pid) {
+    eval {
+      # Allow server startup
+      sleep(1);
+
+      my $sftp = '/Users/tj/local/openssh-7.9p1/bin/sftp';
+
+      my @cmd = (
+        $sftp,
+        '-oBatchMode=yes',
+        '-oCheckHostIP=no',
+        '-oCompression=yes',
+        "-oPort=$port",
+        "-oIdentityFile=$rsa_priv_key",
+        '-oPubkeyAuthentication=yes',
+        '-oStrictHostKeyChecking=no',
+        '-vvv',
+        '-b',
+        $batch_file,
+        "$setup->{user}\@127.0.0.1",
+      );
+
+      my $sftp_rh = IO::Handle->new();
+      my $sftp_wh = IO::Handle->new();
+      my $sftp_eh = IO::Handle->new();
+
+      $sftp_wh->autoflush(1);
+
+      local $SIG{CHLD} = 'DEFAULT';
+
+      # Make sure that the perms on the priv key are what OpenSSH wants
+      unless (chmod(0400, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0400: $!");
+      }
+
+      if ($ENV{TEST_VERBOSE}) {
+        print STDERR "Executing: ", join(' ', @cmd), "\n";
+      }
+
+      my $sftp_pid = open3($sftp_wh, $sftp_rh, $sftp_eh, @cmd);
+      waitpid($sftp_pid, 0);
+      my $exit_status = $?;
+
+      # Restore the perms on the priv key
+      unless (chmod(0644, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0644: $!");
+      }
+
+      my ($res, $errstr);
+      if ($exit_status >> 8 == 0) {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 0;
+
+      } else {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 1;
+      }
+
+      unless ($res == 0) {
+        die("Can't list files on server: $errstr");
+      }
+    };
+    if ($@) {
+      $ex = $@;
+    }
+
+    $wfh->print("done\n");
+    $wfh->flush();
+
+  } else {
+    eval { server_wait($setup->{config_file}, $rfh) };
+    if ($@) {
+      warn($@);
+      exit 1;
+    }
+
+    exit 0;
+  }
+
+  # Stop server
+  server_stop($setup->{pid_file});
+  $self->assert_child_ok($pid);
+
+  test_cleanup($setup->{log_file}, $ex);
+}
+
+sub ssh2_ext_mac_hmac_sha256_etm_openssh {
+  my $self = shift;
+  my $tmpdir = $self->{tmpdir};
+  my $setup = test_setup($tmpdir, 'sftp');
+
+  my $rsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_rsa_key');
+  my $dsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_dsa_key');
+
+  my $rsa_priv_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key');
+  my $rsa_pub_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key.pub');
+  my $rsa_rfc4716_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/authorized_rsa_keys');
+
+  my $authorized_keys = File::Spec->rel2abs("$tmpdir/.authorized_keys");
+  unless (copy($rsa_rfc4716_key, $authorized_keys)) {
+    die("Can't copy $rsa_rfc4716_key to $authorized_keys: $!");
+  }
+
+  my $batch_file = File::Spec->rel2abs("$tmpdir/sftp-batch.conf");
+  if (open(my $fh, "> $batch_file")) {
+    print $fh "ls -al\n";
+
+    unless (close($fh)) {
+      die("Can't write $batch_file: $!");
+    }
+
+  } else {
+    die("Can't open $batch_file: $!");
+  }
+
+  my $config = {
+    PidFile => $setup->{pid_file},
+    ScoreboardFile => $setup->{scoreboard_file},
+    SystemLog => $setup->{log_file},
+    TraceLog => $setup->{log_file},
+    Trace => 'DEFAULT:10 lock:0 scoreboard:0 ssh2:30 sftp:30',
+
+    AuthUserFile => $setup->{auth_user_file},
+    AuthGroupFile => $setup->{auth_group_file},
+
+    IfModules => {
+      'mod_delay.c' => {
+        DelayEngine => 'off',
+      },
+
+      'mod_sftp.c' => [
+        "SFTPEngine on",
+        "SFTPLog $setup->{log_file}",
+        "SFTPHostKey $rsa_host_key",
+        "SFTPHostKey $dsa_host_key",
+        "SFTPAuthorizedUserKeys file:~/.authorized_keys",
+        'SFTPDigests hmac-sha2-256-etm@openssh.com',
+      ],
+    },
+  };
+
+  my ($port, $config_user, $config_group) = config_write($setup->{config_file},
+    $config);
+
+  # Open pipes, for use between the parent and child processes.  Specifically,
+  # the child will indicate when it's done with its test by writing a message
+  # to the parent.
+  my ($rfh, $wfh);
+  unless (pipe($rfh, $wfh)) {
+    die("Can't open pipe: $!");
+  }
+
+  my $ex;
+
+  # Fork child
+  $self->handle_sigchld();
+  defined(my $pid = fork()) or die("Can't fork: $!");
+  if ($pid) {
+    eval {
+      # Allow server startup
+      sleep(1);
+
+      my $sftp = '/Users/tj/local/openssh-7.9p1/bin/sftp';
+
+      my @cmd = (
+        $sftp,
+        '-oBatchMode=yes',
+        '-oCheckHostIP=no',
+        '-oCompression=yes',
+        "-oPort=$port",
+        "-oIdentityFile=$rsa_priv_key",
+        '-oPubkeyAuthentication=yes',
+        '-oStrictHostKeyChecking=no',
+        '-vvv',
+        '-b',
+        $batch_file,
+        "$setup->{user}\@127.0.0.1",
+      );
+
+      my $sftp_rh = IO::Handle->new();
+      my $sftp_wh = IO::Handle->new();
+      my $sftp_eh = IO::Handle->new();
+
+      $sftp_wh->autoflush(1);
+
+      local $SIG{CHLD} = 'DEFAULT';
+
+      # Make sure that the perms on the priv key are what OpenSSH wants
+      unless (chmod(0400, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0400: $!");
+      }
+
+      if ($ENV{TEST_VERBOSE}) {
+        print STDERR "Executing: ", join(' ', @cmd), "\n";
+      }
+
+      my $sftp_pid = open3($sftp_wh, $sftp_rh, $sftp_eh, @cmd);
+      waitpid($sftp_pid, 0);
+      my $exit_status = $?;
+
+      # Restore the perms on the priv key
+      unless (chmod(0644, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0644: $!");
+      }
+
+      my ($res, $errstr);
+      if ($exit_status >> 8 == 0) {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 0;
+
+      } else {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 1;
+      }
+
+      unless ($res == 0) {
+        die("Can't list files on server: $errstr");
+      }
+    };
+    if ($@) {
+      $ex = $@;
+    }
+
+    $wfh->print("done\n");
+    $wfh->flush();
+
+  } else {
+    eval { server_wait($setup->{config_file}, $rfh) };
+    if ($@) {
+      warn($@);
+      exit 1;
+    }
+
+    exit 0;
+  }
+
+  # Stop server
+  server_stop($setup->{pid_file});
+  $self->assert_child_ok($pid);
+
+  test_cleanup($setup->{log_file}, $ex);
+}
+
+sub ssh2_ext_mac_hmac_sha512_etm_openssh {
+  my $self = shift;
+  my $tmpdir = $self->{tmpdir};
+  my $setup = test_setup($tmpdir, 'sftp');
+
+  my $rsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_rsa_key');
+  my $dsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_dsa_key');
+
+  my $rsa_priv_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key');
+  my $rsa_pub_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key.pub');
+  my $rsa_rfc4716_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/authorized_rsa_keys');
+
+  my $authorized_keys = File::Spec->rel2abs("$tmpdir/.authorized_keys");
+  unless (copy($rsa_rfc4716_key, $authorized_keys)) {
+    die("Can't copy $rsa_rfc4716_key to $authorized_keys: $!");
+  }
+
+  my $batch_file = File::Spec->rel2abs("$tmpdir/sftp-batch.conf");
+  if (open(my $fh, "> $batch_file")) {
+    print $fh "ls -al\n";
+
+    unless (close($fh)) {
+      die("Can't write $batch_file: $!");
+    }
+
+  } else {
+    die("Can't open $batch_file: $!");
+  }
+
+  my $config = {
+    PidFile => $setup->{pid_file},
+    ScoreboardFile => $setup->{scoreboard_file},
+    SystemLog => $setup->{log_file},
+    TraceLog => $setup->{log_file},
+    Trace => 'DEFAULT:10 lock:0 scoreboard:0 ssh2:30 sftp:30',
+
+    AuthUserFile => $setup->{auth_user_file},
+    AuthGroupFile => $setup->{auth_group_file},
+
+    IfModules => {
+      'mod_delay.c' => {
+        DelayEngine => 'off',
+      },
+
+      'mod_sftp.c' => [
+        "SFTPEngine on",
+        "SFTPLog $setup->{log_file}",
+        "SFTPHostKey $rsa_host_key",
+        "SFTPHostKey $dsa_host_key",
+        "SFTPAuthorizedUserKeys file:~/.authorized_keys",
+        'SFTPDigests hmac-sha2-512-etm@openssh.com',
+      ],
+    },
+  };
+
+  my ($port, $config_user, $config_group) = config_write($setup->{config_file},
+    $config);
+
+  # Open pipes, for use between the parent and child processes.  Specifically,
+  # the child will indicate when it's done with its test by writing a message
+  # to the parent.
+  my ($rfh, $wfh);
+  unless (pipe($rfh, $wfh)) {
+    die("Can't open pipe: $!");
+  }
+
+  my $ex;
+
+  # Fork child
+  $self->handle_sigchld();
+  defined(my $pid = fork()) or die("Can't fork: $!");
+  if ($pid) {
+    eval {
+      # Allow server startup
+      sleep(1);
+
+      my $sftp = '/Users/tj/local/openssh-7.9p1/bin/sftp';
+
+      my @cmd = (
+        $sftp,
+        '-oBatchMode=yes',
+        '-oCheckHostIP=no',
+        '-oCompression=yes',
+        "-oPort=$port",
+        "-oIdentityFile=$rsa_priv_key",
+        '-oPubkeyAuthentication=yes',
+        '-oStrictHostKeyChecking=no',
+        '-vvv',
+        '-b',
+        $batch_file,
+        "$setup->{user}\@127.0.0.1",
+      );
+
+      my $sftp_rh = IO::Handle->new();
+      my $sftp_wh = IO::Handle->new();
+      my $sftp_eh = IO::Handle->new();
+
+      $sftp_wh->autoflush(1);
+
+      local $SIG{CHLD} = 'DEFAULT';
+
+      # Make sure that the perms on the priv key are what OpenSSH wants
+      unless (chmod(0400, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0400: $!");
+      }
+
+      if ($ENV{TEST_VERBOSE}) {
+        print STDERR "Executing: ", join(' ', @cmd), "\n";
+      }
+
+      my $sftp_pid = open3($sftp_wh, $sftp_rh, $sftp_eh, @cmd);
+      waitpid($sftp_pid, 0);
+      my $exit_status = $?;
+
+      # Restore the perms on the priv key
+      unless (chmod(0644, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0644: $!");
+      }
+
+      my ($res, $errstr);
+      if ($exit_status >> 8 == 0) {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 0;
+
+      } else {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 1;
+      }
+
+      unless ($res == 0) {
+        die("Can't list files on server: $errstr");
+      }
+    };
+    if ($@) {
+      $ex = $@;
+    }
+
+    $wfh->print("done\n");
+    $wfh->flush();
+
+  } else {
+    eval { server_wait($setup->{config_file}, $rfh) };
+    if ($@) {
+      warn($@);
+      exit 1;
+    }
+
+    exit 0;
+  }
+
+  # Stop server
+  server_stop($setup->{pid_file});
+  $self->assert_child_ok($pid);
+
+  test_cleanup($setup->{log_file}, $ex);
+}
+
+sub ssh2_ext_mac_umac_64_etm_openssh {
+  my $self = shift;
+  my $tmpdir = $self->{tmpdir};
+  my $setup = test_setup($tmpdir, 'sftp');
+
+  my $rsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_rsa_key');
+  my $dsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_dsa_key');
+
+  my $rsa_priv_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key');
+  my $rsa_pub_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key.pub');
+  my $rsa_rfc4716_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/authorized_rsa_keys');
+
+  my $authorized_keys = File::Spec->rel2abs("$tmpdir/.authorized_keys");
+  unless (copy($rsa_rfc4716_key, $authorized_keys)) {
+    die("Can't copy $rsa_rfc4716_key to $authorized_keys: $!");
+  }
+
+  my $batch_file = File::Spec->rel2abs("$tmpdir/sftp-batch.conf");
+  if (open(my $fh, "> $batch_file")) {
+    print $fh "ls -al\n";
+
+    unless (close($fh)) {
+      die("Can't write $batch_file: $!");
+    }
+
+  } else {
+    die("Can't open $batch_file: $!");
+  }
+
+  my $config = {
+    PidFile => $setup->{pid_file},
+    ScoreboardFile => $setup->{scoreboard_file},
+    SystemLog => $setup->{log_file},
+    TraceLog => $setup->{log_file},
+    Trace => 'DEFAULT:10 lock:0 scoreboard:0 ssh2:30 sftp:30',
+
+    AuthUserFile => $setup->{auth_user_file},
+    AuthGroupFile => $setup->{auth_group_file},
+
+    IfModules => {
+      'mod_delay.c' => {
+        DelayEngine => 'off',
+      },
+
+      'mod_sftp.c' => [
+        "SFTPEngine on",
+        "SFTPLog $setup->{log_file}",
+        "SFTPHostKey $rsa_host_key",
+        "SFTPHostKey $dsa_host_key",
+        "SFTPAuthorizedUserKeys file:~/.authorized_keys",
+        'SFTPDigests umac-64-etm@openssh.com',
+      ],
+    },
+  };
+
+  my ($port, $config_user, $config_group) = config_write($setup->{config_file},
+    $config);
+
+  # Open pipes, for use between the parent and child processes.  Specifically,
+  # the child will indicate when it's done with its test by writing a message
+  # to the parent.
+  my ($rfh, $wfh);
+  unless (pipe($rfh, $wfh)) {
+    die("Can't open pipe: $!");
+  }
+
+  my $ex;
+
+  # Fork child
+  $self->handle_sigchld();
+  defined(my $pid = fork()) or die("Can't fork: $!");
+  if ($pid) {
+    eval {
+      # Allow server startup
+      sleep(1);
+
+      my $sftp = '/Users/tj/local/openssh-7.9p1/bin/sftp';
+
+      my @cmd = (
+        $sftp,
+        '-oBatchMode=yes',
+        '-oCheckHostIP=no',
+        '-oCompression=yes',
+        "-oPort=$port",
+        "-oIdentityFile=$rsa_priv_key",
+        '-oPubkeyAuthentication=yes',
+        '-oStrictHostKeyChecking=no',
+        '-vvv',
+        '-b',
+        $batch_file,
+        "$setup->{user}\@127.0.0.1",
+      );
+
+      my $sftp_rh = IO::Handle->new();
+      my $sftp_wh = IO::Handle->new();
+      my $sftp_eh = IO::Handle->new();
+
+      $sftp_wh->autoflush(1);
+
+      local $SIG{CHLD} = 'DEFAULT';
+
+      # Make sure that the perms on the priv key are what OpenSSH wants
+      unless (chmod(0400, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0400: $!");
+      }
+
+      if ($ENV{TEST_VERBOSE}) {
+        print STDERR "Executing: ", join(' ', @cmd), "\n";
+      }
+
+      my $sftp_pid = open3($sftp_wh, $sftp_rh, $sftp_eh, @cmd);
+      waitpid($sftp_pid, 0);
+      my $exit_status = $?;
+
+      # Restore the perms on the priv key
+      unless (chmod(0644, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0644: $!");
+      }
+
+      my ($res, $errstr);
+      if ($exit_status >> 8 == 0) {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 0;
+
+      } else {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 1;
+      }
+
+      unless ($res == 0) {
+        die("Can't list files on server: $errstr");
+      }
+    };
+    if ($@) {
+      $ex = $@;
+    }
+
+    $wfh->print("done\n");
+    $wfh->flush();
+
+  } else {
+    eval { server_wait($setup->{config_file}, $rfh) };
+    if ($@) {
+      warn($@);
+      exit 1;
+    }
+
+    exit 0;
+  }
+
+  # Stop server
+  server_stop($setup->{pid_file});
+  $self->assert_child_ok($pid);
+
+  test_cleanup($setup->{log_file}, $ex);
+}
+
+sub ssh2_ext_mac_umac_128_etm_openssh {
+  my $self = shift;
+  my $tmpdir = $self->{tmpdir};
+  my $setup = test_setup($tmpdir, 'sftp');
+
+  my $rsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_rsa_key');
+  my $dsa_host_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/ssh_host_dsa_key');
+
+  my $rsa_priv_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key');
+  my $rsa_pub_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/test_rsa_key.pub');
+  my $rsa_rfc4716_key = File::Spec->rel2abs('t/etc/modules/mod_sftp/authorized_rsa_keys');
+
+  my $authorized_keys = File::Spec->rel2abs("$tmpdir/.authorized_keys");
+  unless (copy($rsa_rfc4716_key, $authorized_keys)) {
+    die("Can't copy $rsa_rfc4716_key to $authorized_keys: $!");
+  }
+
+  my $batch_file = File::Spec->rel2abs("$tmpdir/sftp-batch.conf");
+  if (open(my $fh, "> $batch_file")) {
+    print $fh "ls -al\n";
+
+    unless (close($fh)) {
+      die("Can't write $batch_file: $!");
+    }
+
+  } else {
+    die("Can't open $batch_file: $!");
+  }
+
+  my $config = {
+    PidFile => $setup->{pid_file},
+    ScoreboardFile => $setup->{scoreboard_file},
+    SystemLog => $setup->{log_file},
+    TraceLog => $setup->{log_file},
+    Trace => 'DEFAULT:10 lock:0 scoreboard:0 ssh2:30 sftp:30',
+
+    AuthUserFile => $setup->{auth_user_file},
+    AuthGroupFile => $setup->{auth_group_file},
+
+    IfModules => {
+      'mod_delay.c' => {
+        DelayEngine => 'off',
+      },
+
+      'mod_sftp.c' => [
+        "SFTPEngine on",
+        "SFTPLog $setup->{log_file}",
+        "SFTPHostKey $rsa_host_key",
+        "SFTPHostKey $dsa_host_key",
+        "SFTPAuthorizedUserKeys file:~/.authorized_keys",
+        'SFTPDigests umac-128-etm@openssh.com',
+      ],
+    },
+  };
+
+  my ($port, $config_user, $config_group) = config_write($setup->{config_file},
+    $config);
+
+  # Open pipes, for use between the parent and child processes.  Specifically,
+  # the child will indicate when it's done with its test by writing a message
+  # to the parent.
+  my ($rfh, $wfh);
+  unless (pipe($rfh, $wfh)) {
+    die("Can't open pipe: $!");
+  }
+
+  my $ex;
+
+  # Fork child
+  $self->handle_sigchld();
+  defined(my $pid = fork()) or die("Can't fork: $!");
+  if ($pid) {
+    eval {
+      # Allow server startup
+      sleep(1);
+
+      my $sftp = '/Users/tj/local/openssh-7.9p1/bin/sftp';
+
+      my @cmd = (
+        $sftp,
+        '-oBatchMode=yes',
+        '-oCheckHostIP=no',
+        '-oCompression=yes',
+        "-oPort=$port",
+        "-oIdentityFile=$rsa_priv_key",
+        '-oPubkeyAuthentication=yes',
+        '-oStrictHostKeyChecking=no',
+        '-vvv',
+        '-b',
+        $batch_file,
+        "$setup->{user}\@127.0.0.1",
+      );
+
+      my $sftp_rh = IO::Handle->new();
+      my $sftp_wh = IO::Handle->new();
+      my $sftp_eh = IO::Handle->new();
+
+      $sftp_wh->autoflush(1);
+
+      local $SIG{CHLD} = 'DEFAULT';
+
+      # Make sure that the perms on the priv key are what OpenSSH wants
+      unless (chmod(0400, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0400: $!");
+      }
+
+      if ($ENV{TEST_VERBOSE}) {
+        print STDERR "Executing: ", join(' ', @cmd), "\n";
+      }
+
+      my $sftp_pid = open3($sftp_wh, $sftp_rh, $sftp_eh, @cmd);
+      waitpid($sftp_pid, 0);
+      my $exit_status = $?;
+
+      # Restore the perms on the priv key
+      unless (chmod(0644, $rsa_priv_key)) {
+        die("Can't set perms on $rsa_priv_key to 0644: $!");
+      }
+
+      my ($res, $errstr);
+      if ($exit_status >> 8 == 0) {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 0;
+
+      } else {
+        $errstr = join('', <$sftp_eh>);
+        if ($ENV{TEST_VERBOSE}) {
+          print STDERR "Stderr: $errstr\n";
+        }
+
+        $res = 1;
+      }
+
+      unless ($res == 0) {
+        die("Can't list files on server: $errstr");
+      }
+    };
+    if ($@) {
+      $ex = $@;
+    }
+
+    $wfh->print("done\n");
+    $wfh->flush();
+
+  } else {
+    eval { server_wait($setup->{config_file}, $rfh) };
+    if ($@) {
+      warn($@);
+      exit 1;
+    }
+
+    exit 0;
+  }
+
+  # Stop server
+  server_stop($setup->{pid_file});
+  $self->assert_child_ok($pid);
+
+  test_cleanup($setup->{log_file}, $ex);
+}
+
 sub ssh2_compress_c2s_none {
   my $self = shift;
   my $tmpdir = $self->{tmpdir};