dsa: Add signature tests

dsa/Cargo.toml

@@ -26,5 +26,6 @@ default = []
 [dev-dependencies]
 pkcs8 = { version = "0.9.0", default-features = false, features = ["pem"] }
 rand = "0.8.5"
+rand_chacha = "0.3.1"
 sha1 = "0.10.1"
 sha2 = "0.10.2"

dsa/src/sig.rs

@@ -4,7 +4,7 @@
 
 use alloc::vec::Vec;
 use num_bigint::BigUint;
-use pkcs8::der::{self, asn1::UIntRef, Decode, Encode, Reader, Sequence, SliceReader};
+use pkcs8::der::{self, asn1::UIntRef, Decode, Encode, Reader, Sequence};
 
 /// Container of the DSA signature
 #[derive(Clone)]
@@ -35,16 +35,6 @@ impl Signature {
         signature
     }
 
-    /// Decode a Signature from its DER representation
-    ///
-    /// # Errors
-    ///
-    /// See the [`der` errors](::pkcs8::der::Error)
-    pub fn from_der(data: &[u8]) -> der::Result<Self> {
-        let mut reader = SliceReader::new(data)?;
-        reader.decode()
-    }
-
     /// Signature part r
     #[must_use]
     pub fn r(&self) -> &BigUint {
@@ -66,13 +56,15 @@ impl AsRef<[u8]> for Signature {
 
 impl<'a> Decode<'a> for Signature {
     fn decode<R: Reader<'a>>(reader: &mut R) -> der::Result<Self> {
-        let r = reader.decode::<UIntRef<'_>>()?;
-        let s = reader.decode::<UIntRef<'_>>()?;
+        reader.sequence(|sequence| {
+            let r = sequence.decode::<UIntRef<'_>>()?;
+            let s = sequence.decode::<UIntRef<'_>>()?;
 
-        let r = BigUint::from_bytes_be(r.as_bytes());
-        let s = BigUint::from_bytes_be(s.as_bytes());
+            let r = BigUint::from_bytes_be(r.as_bytes());
+            let s = BigUint::from_bytes_be(s.as_bytes());
 
-        Ok(Self::from_components(r, s))
+            Ok(Self::from_components(r, s))
+        })
     }
 }
 

dsa/tests/signature.rs

@@ -0,0 +1,89 @@
+#![allow(deprecated)]
+
+use digest::Digest;
+use dsa::{consts::DSA_1024_160, Components, PrivateKey, Signature};
+use pkcs8::der::{Decode, Encode};
+use rand::{CryptoRng, RngCore, SeedableRng};
+use rand_chacha::ChaCha8Rng;
+use sha2::Sha256;
+use signature::{DigestVerifier, RandomizedDigestSigner};
+
+/// Seed used for the ChaCha8 RNG
+const SEED: u64 = 0x2103_1949;
+
+/// Message to be signed/verified
+const MESSAGE: &[u8] = b"test";
+
+/// Message signed by this crate using the keys generated by this CSPRNG
+///
+/// This signature was generated using the keys generated by this CSPRNG (the per-message `k` component was also generated using the CSPRNG)
+const MESSAGE_SIGNATURE_CRATE_ASN1: &[u8] = &[
+    0x30, 0x2C, 0x02, 0x14, 0x45, 0x1D, 0xE5, 0x76, 0x21, 0xD8, 0xFD, 0x76, 0xC1, 0x6F, 0x45, 0x4E,
+    0xDE, 0x5F, 0x09, 0x79, 0x76, 0x52, 0xF3, 0xA5, 0x02, 0x14, 0x53, 0x60, 0xE6, 0xB7, 0xF0, 0xCF,
+    0xAE, 0x49, 0xB1, 0x58, 0x5C, 0xCF, 0x5F, 0x3F, 0x94, 0x49, 0x21, 0xA0, 0xBF, 0xD2,
+];
+
+/// Message signed by OpenSSL using the keys generated by this CSPRNG
+///
+/// This signature was generated using the SHA-256 digest
+const MESSAGE_SIGNATURE_OPENSSL_ASN1: &[u8] = &[
+    0x30, 0x2C, 0x02, 0x14, 0x6D, 0xB3, 0x8E, 0xAF, 0x97, 0x13, 0x7E, 0x07, 0xFF, 0x24, 0xB8, 0x66,
+    0x97, 0x18, 0xE1, 0x6F, 0xD7, 0x9A, 0x28, 0x2D, 0x02, 0x14, 0x47, 0x8C, 0x0B, 0x96, 0x51, 0x08,
+    0x08, 0xC8, 0x34, 0x9D, 0x0D, 0x41, 0xC7, 0x73, 0x0F, 0xB5, 0x9C, 0xBB, 0x00, 0x34,
+];
+
+/// Get the seeded CSPRNG
+fn seeded_csprng() -> impl CryptoRng + RngCore {
+    ChaCha8Rng::seed_from_u64(SEED)
+}
+
+/// Generate a DSA keypair using a seeded CSPRNG
+fn generate_deterministic_keypair() -> PrivateKey {
+    let mut rng = seeded_csprng();
+    let components = Components::generate(&mut rng, DSA_1024_160);
+    PrivateKey::generate(&mut rng, components)
+}
+
+#[test]
+fn decode_encode_signature() {
+    let signature_openssl =
+        Signature::from_der(MESSAGE_SIGNATURE_OPENSSL_ASN1).expect("Failed to decode signature");
+    let encoded_signature_openssl = signature_openssl
+        .to_vec()
+        .expect("Failed to encode signature");
+
+    assert_eq!(MESSAGE_SIGNATURE_OPENSSL_ASN1, encoded_signature_openssl);
+
+    let signature_crate =
+        Signature::from_der(MESSAGE_SIGNATURE_CRATE_ASN1).expect("Failed to decode signature");
+    let encoded_signature_crate = signature_crate
+        .to_vec()
+        .expect("Failed to encode signature");
+
+    assert_eq!(MESSAGE_SIGNATURE_CRATE_ASN1, encoded_signature_crate);
+}
+
+#[test]
+fn sign_message() {
+    let private_key = generate_deterministic_keypair();
+    let generated_signature =
+        private_key.sign_digest_with_rng(seeded_csprng(), Sha256::new().chain_update(MESSAGE));
+
+    let expected_signature =
+        Signature::from_der(MESSAGE_SIGNATURE_CRATE_ASN1).expect("Failed to decode signature");
+
+    assert_eq!(generated_signature, expected_signature);
+}
+
+#[test]
+fn verify_signature() {
+    let private_key = generate_deterministic_keypair();
+    let public_key = private_key.public_key();
+
+    let signature = Signature::from_der(MESSAGE_SIGNATURE_OPENSSL_ASN1)
+        .expect("Failed to parse ASN.1 representation of the test signature");
+
+    assert!(public_key
+        .verify_digest(Sha256::new().chain_update(MESSAGE), &signature)
+        .is_ok());
+}