distinguish between RFC 4754 (concatenated) and RFC 3279 (DER encoded) ECDSA signatures

1 files changed, 100 insertions, 116 deletions

diff --git a/src/libstrongswan/plugins/openssl/openssl_ec_private_key.c b/src/libstrongswan/plugins/openssl/openssl_ec_private_key.c
index f333bd32d..576eaf5c5 100644
--- a/src/libstrongswan/plugins/openssl/openssl_ec_private_key.c
+++ b/src/libstrongswan/plugins/openssl/openssl_ec_private_key.c
@@ -43,153 +43,129 @@ struct private_openssl_ec_private_key_t {
 	/**
 	 * reference count
 	 */
-	refcount_t ref;	
+	refcount_t ref;
 };
 
-/**
- * Mapping from the signature scheme defined in (RFC 4754) to the elliptic
- * curve and the hash algorithm
- */
-typedef struct {
-	/**
-	 * Scheme specified in RFC 4754
-	 */
-	int scheme;
-	
-	/**
-	 * NID of the hash
-	 */
-	int hash;
-	
-	/**
-	 * NID of the curve
-	 */
-	int curve;
-} openssl_ecdsa_scheme_t;
-
-#define END_OF_LIST -1
-
-/**
- * Signature schemes
- */
-static openssl_ecdsa_scheme_t ecdsa_schemes[] = {
-	{SIGN_ECDSA_WITH_SHA1,	NID_sha1,	-1},
-	{SIGN_ECDSA_256,		NID_sha256,	NID_X9_62_prime256v1},
-	{SIGN_ECDSA_384,		NID_sha384,	NID_secp384r1},
-	{SIGN_ECDSA_521,		NID_sha512,	NID_secp521r1},
-	{END_OF_LIST,			0,			0},
-};
-
-/**
- * Look up the hash and curve of a signature scheme
- */
-static bool lookup_scheme(int scheme, int *hash, int *curve)
-{
-	openssl_ecdsa_scheme_t *ecdsa_scheme = ecdsa_schemes;
-	while (ecdsa_scheme->scheme != END_OF_LIST)
-	{
-		if (scheme == ecdsa_scheme->scheme)
-		{
-			*hash = ecdsa_scheme->hash;
-			*curve = ecdsa_scheme->curve;
-			return TRUE;
-		}
-		ecdsa_scheme++;
-	}
-	return FALSE;
-}
-
 /* from ec public key */
 bool openssl_ec_fingerprint(EC_KEY *ec, key_encoding_type_t type, chunk_t *fp);
 
 /**
- * Convert an ECDSA_SIG to a chunk by concatenating r and s.
- * This function allocates memory for the chunk.
- */
-static bool sig2chunk(const EC_GROUP *group, ECDSA_SIG *sig, chunk_t *chunk)
-{
-	return openssl_bn_cat(EC_FIELD_ELEMENT_LEN(group), sig->r, sig->s, chunk);
-}
-
-/**
- * Build the signature
+ * Build a signature as in RFC 4754
  */
 static bool build_signature(private_openssl_ec_private_key_t *this,
 							chunk_t hash, chunk_t *signature)
 {
+	bool built = FALSE;
 	ECDSA_SIG *sig;
-	bool success;
 	
 	sig = ECDSA_do_sign(hash.ptr, hash.len, this->ec);
-	if (!sig)
+	if (sig)
 	{
-		return FALSE;
+		/* concatenate BNs r/s to a signature chunk */
+		built = openssl_bn_cat(EC_FIELD_ELEMENT_LEN(EC_KEY_get0_group(this->ec)),
+							   sig->r, sig->s, signature);
+		ECDSA_SIG_free(sig);
 	}
-	success = sig2chunk(EC_KEY_get0_group(this->ec), sig, signature);
-	ECDSA_SIG_free(sig);
-	return success;
+	return built;
 }
 
 /**
- * Implementation of private_key_t.get_type.
+ * Build a RFC 4754 signature for a specified curve and hash algorithm
  */
-static key_type_t get_type(private_openssl_ec_private_key_t *this)
+static bool build_curve_signature(private_openssl_ec_private_key_t *this,
+								signature_scheme_t scheme, int nid_hash,
+								int nid_curve, chunk_t data, chunk_t *signature)
 {
-	return KEY_ECDSA;
+	const EC_GROUP *my_group;
+	EC_GROUP *req_group;
+	chunk_t hash;
+	bool built;
+	
+	req_group = EC_GROUP_new_by_curve_name(nid_curve);
+	if (!req_group)
+	{
+		DBG1("signature scheme %N not supported in EC (required curve "
+			 "not supported)", signature_scheme_names, scheme);
+		return FALSE;
+	}
+	my_group = EC_KEY_get0_group(this->ec);
+	if (EC_GROUP_cmp(my_group, req_group, NULL) != 0)
+	{
+		DBG1("signature scheme %N not supported by private key",
+			 signature_scheme_names, scheme);
+		return FALSE;
+	}
+	EC_GROUP_free(req_group);
+	if (!openssl_hash_chunk(nid_hash, data, &hash))
+	{
+		return FALSE;
+	}
+	built = build_signature(this, data, signature);
+	chunk_free(&hash);
+	return built;
 }
 
 /**
- * Implementation of private_key_t.sign.
+ * Build a DER encoded signature as in RFC 3279
  */
-static bool sign(private_openssl_ec_private_key_t *this, signature_scheme_t scheme, 
-				 chunk_t data, chunk_t *signature)
+static bool build_der_signature(private_openssl_ec_private_key_t *this,
+								int hash_nid, chunk_t data, chunk_t *signature)
 {
-	bool success;
+	chunk_t hash, sig;
+	int siglen = 0;
+	bool built;
 	
-	if (scheme == SIGN_ECDSA_WITH_NULL)
+	if (!openssl_hash_chunk(hash_nid, data, &hash))
 	{
-		success = build_signature(this, data, signature);
+		return FALSE;
+	}
+	sig = chunk_alloc(ECDSA_size(this->ec));
+	built = ECDSA_sign(0, hash.ptr, hash.len, sig.ptr, &siglen, this->ec) == 1;
+	sig.len = siglen;
+	if (built)
+	{
+		*signature = sig;
 	}
 	else
 	{
-		EC_GROUP *req_group;
-		const EC_GROUP *my_group;
-		chunk_t hash = chunk_empty;
-		int hash_type, curve;
-		
-		if (!lookup_scheme(scheme, &hash_type, &curve))
-		{
-			DBG1("signature scheme %N not supported in EC",
-					 signature_scheme_names, scheme);
-			return FALSE;
-		}
-		
-		if (curve != -1)
-		{
-			req_group = EC_GROUP_new_by_curve_name(curve);
-			if (!req_group)
-			{
-				DBG1("signature scheme %N not supported in EC (required curve "
-					 "not supported)", signature_scheme_names, scheme);
-				return FALSE;
-			}
-			my_group = EC_KEY_get0_group(this->ec);
-			if (EC_GROUP_cmp(my_group, req_group, NULL) != 0)
-			{
-				DBG1("signature scheme %N not supported by private key",
-					 signature_scheme_names, scheme);
-				return FALSE;
-			}
-			EC_GROUP_free(req_group);
-		}
-		if (!openssl_hash_chunk(hash_type, data, &hash))
-		{
+		free(sig.ptr);
+	}
+	free(hash.ptr);
+	return built;
+}
+
+/**
+ * Implementation of private_key_t.sign.
+ */
+static bool sign(private_openssl_ec_private_key_t *this,
+				 signature_scheme_t scheme, chunk_t data, chunk_t *signature)
+{
+	switch (scheme)
+	{
+		case SIGN_ECDSA_WITH_NULL:
+			return build_signature(this, data, signature);
+		case SIGN_ECDSA_WITH_SHA1_DER:
+			return build_der_signature(this, NID_sha1, data, signature);
+		case SIGN_ECDSA_WITH_SHA256_DER:
+			return build_der_signature(this, NID_sha256, data, signature);
+		case SIGN_ECDSA_WITH_SHA384_DER:
+			return build_der_signature(this, NID_sha384, data, signature);
+		case SIGN_ECDSA_WITH_SHA512_DER:
+			return build_der_signature(this, NID_sha512, data, signature);
+		case SIGN_ECDSA_256:
+			return build_curve_signature(this, scheme, NID_X9_62_prime256v1,
+										 NID_sha256, data, signature);
+		case SIGN_ECDSA_384:
+			return build_curve_signature(this, scheme, NID_secp384r1,
+										 NID_sha384, data, signature);
+		case SIGN_ECDSA_521:
+			return build_curve_signature(this, scheme, NID_secp521r1,
+										 NID_sha512, data, signature);
+		default:
+			DBG1("signature scheme %N not supported",
+				 signature_scheme_names, scheme);
 			return FALSE;
-		}
-		success = build_signature(this, hash, signature);
-		chunk_free(&hash);
-	}	
-	return success;
+	}
 }
 
 /**
@@ -211,6 +187,14 @@ static size_t get_keysize(private_openssl_ec_private_key_t *this)
 }
 
 /**
+ * Implementation of private_key_t.get_type.
+ */
+static key_type_t get_type(private_openssl_ec_private_key_t *this)
+{
+	return KEY_ECDSA;
+}
+
+/**
  * Implementation of private_key_t.get_public_key.
  */
 static public_key_t* get_public_key(private_openssl_ec_private_key_t *this)