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Merge bitcoin#854: Rename msg32 to msghash32 in ecdsa_sign/verify and…
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… add explanation

6e85d67 Rename tweak to tweak32 in public API (Jonas Nick)
f587f04 Rename msg32 to msghash32 in ecdsa_sign/verify and add explanation (Jonas Nick)

Pull request description:

  This fixes bitcoin#307 if there's nothing else that's confusing.

ACKs for top commit:
  real-or-random:
    ACK 6e85d67 I inspected the diff

Tree-SHA512: 1b0dc9dfffd497058dc39c962a512ed6d7f89218020fef9d2c03aaae1aefbf272b918c4fe6503434b62547714855fe1b8b89f2366f3ae6cde16143207c9e6b86
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real-or-random committed Dec 7, 2020
2 parents 8f0c6f1 + 6e85d67 commit dc6e5c3
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Showing 4 changed files with 70 additions and 63 deletions.
45 changes: 26 additions & 19 deletions include/secp256k1.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -452,7 +452,14 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact(
* 0: incorrect or unparseable signature
* Args: ctx: a secp256k1 context object, initialized for verification.
* In: sig: the signature being verified (cannot be NULL)
* msg32: the 32-byte message hash being verified (cannot be NULL)
* msghash32: the 32-byte message hash being verified (cannot be NULL).
* The verifier must make sure to apply a cryptographic
* hash function to the message by itself and not accept an
* msghash32 value directly. Otherwise, it would be easy to
* create a "valid" signature without knowledge of the
* secret key. See also
* https://bitcoin.stackexchange.com/a/81116/35586 for more
* background on this topic.
* pubkey: pointer to an initialized public key to verify with (cannot be NULL)
*
* To avoid accepting malleable signatures, only ECDSA signatures in lower-S
Expand All @@ -467,7 +474,7 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact(
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
const secp256k1_context* ctx,
const secp256k1_ecdsa_signature *sig,
const unsigned char *msg32,
const unsigned char *msghash32,
const secp256k1_pubkey *pubkey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);

Expand Down Expand Up @@ -532,20 +539,20 @@ SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_def
*
* Returns: 1: signature created
* 0: the nonce generation function failed, or the secret key was invalid.
* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
* In: msg32: the 32-byte message hash being signed (cannot be NULL)
* seckey: pointer to a 32-byte secret key (cannot be NULL)
* noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
* In: msghash32: the 32-byte message hash being signed (cannot be NULL)
* seckey: pointer to a 32-byte secret key (cannot be NULL)
* noncefp: pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
*
* The created signature is always in lower-S form. See
* secp256k1_ecdsa_signature_normalize for more details.
*/
SECP256K1_API int secp256k1_ecdsa_sign(
const secp256k1_context* ctx,
secp256k1_ecdsa_signature *sig,
const unsigned char *msg32,
const unsigned char *msghash32,
const unsigned char *seckey,
secp256k1_nonce_function noncefp,
const void *ndata
Expand Down Expand Up @@ -626,23 +633,23 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_negate(
* invalid according to secp256k1_ec_seckey_verify, this
* function returns 0. seckey will be set to some unspecified
* value if this function returns 0. (cannot be NULL)
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* In: tweak32: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_add(
const secp256k1_context* ctx,
unsigned char *seckey,
const unsigned char *tweak
const unsigned char *tweak32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);

/** Same as secp256k1_ec_seckey_tweak_add, but DEPRECATED. Will be removed in
* future versions. */
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
const secp256k1_context* ctx,
unsigned char *seckey,
const unsigned char *tweak
const unsigned char *tweak32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);

/** Tweak a public key by adding tweak times the generator to it.
Expand All @@ -654,15 +661,15 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
* (cannot be NULL).
* In/Out: pubkey: pointer to a public key object. pubkey will be set to an
* invalid value if this function returns 0 (cannot be NULL).
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* In: tweak32: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
const secp256k1_context* ctx,
secp256k1_pubkey *pubkey,
const unsigned char *tweak
const unsigned char *tweak32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);

/** Tweak a secret key by multiplying it by a tweak.
Expand All @@ -673,23 +680,23 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
* invalid according to secp256k1_ec_seckey_verify, this
* function returns 0. seckey will be set to some unspecified
* value if this function returns 0. (cannot be NULL)
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* In: tweak32: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_tweak_mul(
const secp256k1_context* ctx,
unsigned char *seckey,
const unsigned char *tweak
const unsigned char *tweak32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);

/** Same as secp256k1_ec_seckey_tweak_mul, but DEPRECATED. Will be removed in
* future versions. */
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
const secp256k1_context* ctx,
unsigned char *seckey,
const unsigned char *tweak
const unsigned char *tweak32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);

/** Tweak a public key by multiplying it by a tweak value.
Expand All @@ -699,15 +706,15 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
* (cannot be NULL).
* In/Out: pubkey: pointer to a public key object. pubkey will be set to an
* invalid value if this function returns 0 (cannot be NULL).
* In: tweak: pointer to a 32-byte tweak. If the tweak is invalid according to
* In: tweak32: pointer to a 32-byte tweak. If the tweak is invalid according to
* secp256k1_ec_seckey_verify, this function returns 0. For
* uniformly random 32-byte arrays the chance of being invalid
* is negligible (around 1 in 2^128) (cannot be NULL).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
const secp256k1_context* ctx,
secp256k1_pubkey *pubkey,
const unsigned char *tweak
const unsigned char *tweak32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);

/** Updates the context randomization to protect against side-channel leakage.
Expand Down
24 changes: 12 additions & 12 deletions include/secp256k1_recovery.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -71,17 +71,17 @@ SECP256K1_API int secp256k1_ecdsa_recoverable_signature_serialize_compact(
*
* Returns: 1: signature created
* 0: the nonce generation function failed, or the secret key was invalid.
* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
* In: msg32: the 32-byte message hash being signed (cannot be NULL)
* seckey: pointer to a 32-byte secret key (cannot be NULL)
* noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
* In: msghash32: the 32-byte message hash being signed (cannot be NULL)
* seckey: pointer to a 32-byte secret key (cannot be NULL)
* noncefp: pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
*/
SECP256K1_API int secp256k1_ecdsa_sign_recoverable(
const secp256k1_context* ctx,
secp256k1_ecdsa_recoverable_signature *sig,
const unsigned char *msg32,
const unsigned char *msghash32,
const unsigned char *seckey,
secp256k1_nonce_function noncefp,
const void *ndata
Expand All @@ -91,16 +91,16 @@ SECP256K1_API int secp256k1_ecdsa_sign_recoverable(
*
* Returns: 1: public key successfully recovered (which guarantees a correct signature).
* 0: otherwise.
* Args: ctx: pointer to a context object, initialized for verification (cannot be NULL)
* Out: pubkey: pointer to the recovered public key (cannot be NULL)
* In: sig: pointer to initialized signature that supports pubkey recovery (cannot be NULL)
* msg32: the 32-byte message hash assumed to be signed (cannot be NULL)
* Args: ctx: pointer to a context object, initialized for verification (cannot be NULL)
* Out: pubkey: pointer to the recovered public key (cannot be NULL)
* In: sig: pointer to initialized signature that supports pubkey recovery (cannot be NULL)
* msghash32: the 32-byte message hash assumed to be signed (cannot be NULL)
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_recover(
const secp256k1_context* ctx,
secp256k1_pubkey *pubkey,
const secp256k1_ecdsa_recoverable_signature *sig,
const unsigned char *msg32
const unsigned char *msghash32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);

#ifdef __cplusplus
Expand Down
12 changes: 6 additions & 6 deletions src/modules/recovery/main_impl.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -120,34 +120,34 @@ static int secp256k1_ecdsa_sig_recover(const secp256k1_ecmult_context *ctx, cons
return !secp256k1_gej_is_infinity(&qj);
}

int secp256k1_ecdsa_sign_recoverable(const secp256k1_context* ctx, secp256k1_ecdsa_recoverable_signature *signature, const unsigned char *msg32, const unsigned char *seckey, secp256k1_nonce_function noncefp, const void* noncedata) {
int secp256k1_ecdsa_sign_recoverable(const secp256k1_context* ctx, secp256k1_ecdsa_recoverable_signature *signature, const unsigned char *msghash32, const unsigned char *seckey, secp256k1_nonce_function noncefp, const void* noncedata) {
secp256k1_scalar r, s;
int ret, recid;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
ARG_CHECK(msg32 != NULL);
ARG_CHECK(msghash32 != NULL);
ARG_CHECK(signature != NULL);
ARG_CHECK(seckey != NULL);

ret = secp256k1_ecdsa_sign_inner(ctx, &r, &s, &recid, msg32, seckey, noncefp, noncedata);
ret = secp256k1_ecdsa_sign_inner(ctx, &r, &s, &recid, msghash32, seckey, noncefp, noncedata);
secp256k1_ecdsa_recoverable_signature_save(signature, &r, &s, recid);
return ret;
}

int secp256k1_ecdsa_recover(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const secp256k1_ecdsa_recoverable_signature *signature, const unsigned char *msg32) {
int secp256k1_ecdsa_recover(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, const secp256k1_ecdsa_recoverable_signature *signature, const unsigned char *msghash32) {
secp256k1_ge q;
secp256k1_scalar r, s;
secp256k1_scalar m;
int recid;
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(msg32 != NULL);
ARG_CHECK(msghash32 != NULL);
ARG_CHECK(signature != NULL);
ARG_CHECK(pubkey != NULL);

secp256k1_ecdsa_recoverable_signature_load(ctx, &r, &s, &recid, signature);
VERIFY_CHECK(recid >= 0 && recid < 4); /* should have been caught in parse_compact */
secp256k1_scalar_set_b32(&m, msg32, NULL);
secp256k1_scalar_set_b32(&m, msghash32, NULL);
if (secp256k1_ecdsa_sig_recover(&ctx->ecmult_ctx, &r, &s, &q, &m, recid)) {
secp256k1_pubkey_save(pubkey, &q);
return 1;
Expand Down
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