Remove HRSS confirmation hash. Since the underlying operation is deterministic the confirmation hash isn't needed and SXY didn't use it in their proof. Change-Id: I3a03c20ee79645cf94b10dbfe654c1b88d9aa416 Reviewed-on: https://boringssl-review.googlesource.com/c/33605 Reviewed-by: David Benjamin <davidben@google.com> Commit-Queue: David Benjamin <davidben@google.com>
diff --git a/crypto/hrss/hrss.c b/crypto/hrss/hrss.c index 87241a5..881da78 100644 --- a/crypto/hrss/hrss.c +++ b/crypto/hrss/hrss.c
@@ -2088,10 +2088,9 @@ poly_marshal(out, &prh_plus_m); } -static const char kConfirmationHash[] = "confirmation hash"; static const char kSharedKey[] = "shared key"; -void HRSS_encap(uint8_t out_ciphertext[POLY_BYTES + 32], +void HRSS_encap(uint8_t out_ciphertext[POLY_BYTES], uint8_t out_shared_key[32], const struct HRSS_public_key *in_pub, const uint8_t in[HRSS_SAMPLE_BYTES + HRSS_SAMPLE_BYTES]) { @@ -2109,16 +2108,10 @@ SHA256_CTX hash_ctx; SHA256_Init(&hash_ctx); - SHA256_Update(&hash_ctx, kConfirmationHash, sizeof(kConfirmationHash)); - SHA256_Update(&hash_ctx, m_bytes, sizeof(m_bytes)); - SHA256_Update(&hash_ctx, r_bytes, sizeof(r_bytes)); - SHA256_Final(out_ciphertext + POLY_BYTES, &hash_ctx); - - SHA256_Init(&hash_ctx); SHA256_Update(&hash_ctx, kSharedKey, sizeof(kSharedKey)); SHA256_Update(&hash_ctx, m_bytes, sizeof(m_bytes)); SHA256_Update(&hash_ctx, r_bytes, sizeof(r_bytes)); - SHA256_Update(&hash_ctx, out_ciphertext, POLY_BYTES + 32); + SHA256_Update(&hash_ctx, out_ciphertext, POLY_BYTES); SHA256_Final(out_shared_key, &hash_ctx); } @@ -2166,7 +2159,7 @@ // If the ciphertext is publicly invalid then a random shared key is still // returned to simply the logic of the caller, but this path is not constant // time. - if (ciphertext_len != POLY_BYTES + 32) { + if (ciphertext_len != HRSS_CIPHERTEXT_BYTES) { return; } @@ -2200,7 +2193,9 @@ struct poly3 r3; crypto_word_t ok = poly3_from_poly_checked(&r3, &c); - uint8_t expected_ciphertext[POLY_BYTES + 32]; + uint8_t expected_ciphertext[HRSS_CIPHERTEXT_BYTES]; + OPENSSL_STATIC_ASSERT(HRSS_CIPHERTEXT_BYTES == POLY_BYTES, + "ciphertext is the wrong size"); assert(ciphertext_len == sizeof(expected_ciphertext)); owf(expected_ciphertext, pub, &m_lifted, &c); @@ -2209,12 +2204,6 @@ poly_marshal_mod3(m_bytes, &m); poly_marshal_mod3(r_bytes, &c); - SHA256_Init(&hash_ctx); - SHA256_Update(&hash_ctx, kConfirmationHash, sizeof(kConfirmationHash)); - SHA256_Update(&hash_ctx, m_bytes, sizeof(m_bytes)); - SHA256_Update(&hash_ctx, r_bytes, sizeof(r_bytes)); - SHA256_Final(expected_ciphertext + POLY_BYTES, &hash_ctx); - ok &= constant_time_is_zero_w(CRYPTO_memcmp(ciphertext, expected_ciphertext, sizeof(expected_ciphertext)));
diff --git a/crypto/hrss/hrss_test.cc b/crypto/hrss/hrss_test.cc index b37456c..ead717d 100644 --- a/crypto/hrss/hrss_test.cc +++ b/crypto/hrss/hrss_test.cc
@@ -444,17 +444,14 @@ 0x0a, 0xcf, 0x72, 0x74, 0x76, 0x75, 0x99, 0x4d, 0x3d, 0x9a, 0x4c, 0x54, 0xcd, 0xf8, 0x54, 0xf0, 0xbd, 0x73, 0xe9, 0x4f, 0x29, 0xd0, 0xe1, 0x24, 0x94, 0x52, 0xd6, 0x60, 0x80, 0x71, 0x24, 0x95, 0x92, 0x01, 0x0e, 0xa9, - 0x7e, 0x64, 0x2e, 0xed, 0x51, 0xcc, 0xd2, 0xff, 0xfd, 0x0b, 0xf4, 0x1d, - 0x25, 0x5d, 0x10, 0x87, 0x09, 0x55, 0x06, 0x95, 0xae, 0xb3, 0xef, 0xe9, - 0xaa, 0x36, 0x15, 0x97, 0xe6, 0xf2, 0x24, 0xcf, 0x7d, 0xcd, 0x55, 0x11, - 0xba, 0x20, 0xd0, 0xd7, 0xdc, 0xa6, + 0x7e, 0x64, 0x2e, 0xed, 0x51, 0xcc, 0xd2, 0xff, 0xfd, 0x0b, }; EXPECT_EQ(Bytes(ciphertext), Bytes(kExpectedCiphertext)); static const uint8_t kExpectedSharedKey[HRSS_KEY_BYTES] = { - 0x04, 0x5a, 0x1a, 0xbc, 0x4c, 0x76, 0x47, 0x1f, 0xbf, 0xc9, 0x23, - 0xec, 0xcb, 0x6e, 0x4d, 0x59, 0x8d, 0x3f, 0x90, 0x3e, 0x53, 0x73, - 0x3c, 0x2c, 0x71, 0xcc, 0xac, 0xc5, 0xe0, 0xf2, 0xbc, 0xe8, + 0xbc, 0x98, 0x9c, 0x9c, 0x1f, 0x57, 0x6f, 0x38, 0x0b, 0x5d, 0xc2, + 0x23, 0x7d, 0x01, 0xae, 0x63, 0x17, 0xe8, 0xe4, 0xb2, 0x02, 0xa7, + 0xc4, 0x3a, 0x1b, 0x5a, 0xf3, 0xf8, 0xb5, 0xea, 0x6e, 0x22, }; EXPECT_EQ(Bytes(shared_key), Bytes(kExpectedSharedKey)); @@ -467,9 +464,9 @@ HRSS_decap(shared_key, &pub, &priv, ciphertext, sizeof(ciphertext)); static const uint8_t kExpectedFailureKey[HRSS_KEY_BYTES] = { - 0x3a, 0xec, 0xc0, 0x38, 0x4f, 0xa7, 0x17, 0xb2, 0x77, 0x61, 0xb1, - 0xf8, 0x12, 0x7f, 0xd9, 0x61, 0x67, 0x70, 0x63, 0xbe, 0xa2, 0x72, - 0xfe, 0x1a, 0x82, 0x8d, 0x1d, 0x90, 0xe0, 0x36, 0x69, 0x2d, + 0x8e, 0x19, 0xfe, 0x2b, 0x12, 0x67, 0xef, 0x9a, 0x63, 0x4d, 0x79, + 0x33, 0x8c, 0xce, 0xbf, 0x03, 0xdb, 0x9c, 0xc4, 0xc1, 0x70, 0xe1, + 0x32, 0xa6, 0xb3, 0xd3, 0xa1, 0x43, 0x3c, 0xf1, 0x1f, 0x5a, }; EXPECT_EQ(Bytes(shared_key), Bytes(kExpectedFailureKey)); }
diff --git a/include/openssl/hrss.h b/include/openssl/hrss.h index 4e1c73f..cc5edff 100644 --- a/include/openssl/hrss.h +++ b/include/openssl/hrss.h
@@ -50,7 +50,7 @@ // HRSS_PUBLIC_KEY_BYTES is the number of bytes in a public key. #define HRSS_PUBLIC_KEY_BYTES 1138 // HRSS_CIPHERTEXT_BYTES is the number of bytes in a ciphertext. -#define HRSS_CIPHERTEXT_BYTES (1138 + 32) +#define HRSS_CIPHERTEXT_BYTES 1138 // HRSS_KEY_BYTES is the number of bytes in a shared key. #define HRSS_KEY_BYTES 32 // HRSS_POLY3_BYTES is the number of bytes needed to serialise a mod 3
diff --git a/ssl/test/runner/hrss/hrss.go b/ssl/test/runner/hrss/hrss.go index ebda656..9f4fdd7 100644 --- a/ssl/test/runner/hrss/hrss.go +++ b/ssl/test/runner/hrss/hrss.go
@@ -11,7 +11,7 @@ const ( PublicKeySize = modQBytes - CiphertextSize = modQBytes + 32 + CiphertextSize = modQBytes ) const ( @@ -1058,18 +1058,9 @@ m.marshalS3(mBytes[:]) r.marshalS3(rBytes[:]) + ciphertext = pub.owf(&m, &r) + h := sha256.New() - h.Write([]byte("confirmation hash\x00")) - h.Write(mBytes[:]) - h.Write(rBytes[:]) - confirmationDigest := h.Sum(nil) - - encrypted := pub.owf(&m, &r) - ciphertext = make([]byte, 0, len(encrypted)+len(confirmationDigest)) - ciphertext = append(ciphertext, encrypted...) - ciphertext = append(ciphertext, confirmationDigest...) - - h.Reset() h.Write([]byte("shared key\x00")) h.Write(mBytes[:]) h.Write(rBytes[:]) @@ -1114,12 +1105,12 @@ } func (priv *PrivateKey) Decap(ciphertext []byte) (sharedKey []byte, ok bool) { - if len(ciphertext) != modQBytes+32 { + if len(ciphertext) != modQBytes { return nil, false } var e poly - if !e.unmarshal(ciphertext[:modQBytes]) { + if !e.unmarshal(ciphertext) { return nil, false } @@ -1153,18 +1144,9 @@ m.marshalS3(mBytes[:]) r.marshal(rBytes[:]) - h := sha256.New() - h.Write([]byte("confirmation hash\x00")) - h.Write(mBytes[:]) - h.Write(rBytes[:]) - confirmationDigest := h.Sum(nil) - var rPoly poly rPoly.fromMod3(&r) - encrypted := priv.PublicKey.owf(&m, &rPoly) - expectedCiphertext := make([]byte, 0, len(encrypted)+len(confirmationDigest)) - expectedCiphertext = append(expectedCiphertext, encrypted...) - expectedCiphertext = append(expectedCiphertext, confirmationDigest...) + expectedCiphertext := priv.PublicKey.owf(&m, &rPoly) allOk &= subtle.ConstantTimeCompare(ciphertext, expectedCiphertext) @@ -1172,7 +1154,7 @@ hmacHash.Write(ciphertext) hmacDigest := hmacHash.Sum(nil) - h.Reset() + h := sha256.New() h.Write([]byte("shared key\x00")) h.Write(mBytes[:]) h.Write(rBytes[:])