Add EVP_DigestVerifyInitFromAlgorithm and EVP_DigestSignAlgorithm.

Factor the AlgorithmIdentifier portions of ASN1_item_sign and ASN1_item_verify
out. This makes it possible to initialize a signature context from an
AlgorithmIdentifier without needing the data parsed into an ASN1_ITEM/void*
pair and reserialized.

Change-Id: Idc2e06b1310a3f801aa25de323d39d2b7a44ef50
Reviewed-on: https://boringssl-review.googlesource.com/1916
Reviewed-by: Adam Langley <agl@google.com>

2 files changed, 11 insertions, 106 deletions

diff --git a/crypto/x509/a_sign.c b/crypto/x509/a_sign.c
index a6bf7157..f219c239 100644
--- a/crypto/x509/a_sign.c
+++ b/crypto/x509/a_sign.c
@@ -84,65 +84,20 @@ int ASN1_item_sign_ctx(const ASN1_ITEM *it,
 		X509_ALGOR *algor1, X509_ALGOR *algor2,
 	     	ASN1_BIT_STRING *signature, void *asn, EVP_MD_CTX *ctx)
 	{
-	const EVP_MD *type;
 	EVP_PKEY *pkey;
 	unsigned char *buf_in=NULL,*buf_out=NULL;
 	size_t inl=0,outl=0,outll=0;
-	int signid, paramtype;
-	int rv;
 
-	type = EVP_MD_CTX_md(ctx);
 	pkey = EVP_PKEY_CTX_get0_pkey(ctx->pctx);
 
-	if (!type || !pkey)
+	/* Write out the requested copies of the AlgorithmIdentifier. */
+	if (algor1 && !EVP_DigestSignAlgorithm(ctx, algor1))
 		{
-		OPENSSL_PUT_ERROR(X509, ASN1_item_sign_ctx, X509_R_CONTEXT_NOT_INITIALISED);
-		return 0;
-		}
-
-	if (pkey->ameth->item_sign)
-		{
-		rv = pkey->ameth->item_sign(ctx, it, asn, algor1, algor2,
-						signature);
-		if (rv == 1)
-			outl = signature->length;
-		/* Return value meanings:
-		 * <=0: error.
-		 *   1: method does everything.
-		 *   2: carry on as normal.
-		 *   3: ASN1 method sets algorithm identifiers: just sign.
-		 */
-		if (rv <= 0)
-			OPENSSL_PUT_ERROR(X509, ASN1_item_sign_ctx, ERR_R_EVP_LIB);
-		if (rv <= 1)
-			goto err;
+		goto err;
 		}
-	else
-		rv = 2;
-
-	if (rv == 2)
+	if (algor2 && !EVP_DigestSignAlgorithm(ctx, algor2))
 		{
-		/* TODO(fork): EVP_MD_FLAG_PKEY_METHOD_SIGNATURE seems to mean
-		 * "is SHA". */
-		if (!pkey->ameth ||
-			!OBJ_find_sigid_by_algs(&signid,
-						EVP_MD_type(type),
-						pkey->ameth->pkey_id))
-			{
-			OPENSSL_PUT_ERROR(X509, ASN1_item_sign_ctx, X509_R_DIGEST_AND_KEY_TYPE_NOT_SUPPORTED);
-			return 0;
-			}
-
-		if (pkey->ameth->pkey_flags & ASN1_PKEY_SIGPARAM_NULL)
-			paramtype = V_ASN1_NULL;
-		else
-			paramtype = V_ASN1_UNDEF;
-
-		if (algor1)
-			X509_ALGOR_set0(algor1, OBJ_nid2obj(signid), paramtype, NULL);
-		if (algor2)
-			X509_ALGOR_set0(algor2, OBJ_nid2obj(signid), paramtype, NULL);
-
+		goto err;
 		}
 
 	inl=ASN1_item_i2d(asn,&buf_in, it);
diff --git a/crypto/x509/a_verify.c b/crypto/x509/a_verify.c
index 51f0fd66..e728863f 100644
--- a/crypto/x509/a_verify.c
+++ b/crypto/x509/a_verify.c
@@ -75,69 +75,21 @@ int ASN1_item_verify(const ASN1_ITEM *it, X509_ALGOR *a,
 		ASN1_BIT_STRING *signature, void *asn, EVP_PKEY *pkey)
 	{
 	EVP_MD_CTX ctx;
-	unsigned char *buf_in=NULL;
-	int ret= -1,inl;
-	const EVP_PKEY_ASN1_METHOD *ameth;
-
-	int mdnid, pknid;
+	uint8_t *buf_in = NULL;
+	int ret = 0, inl;
 
 	if (!pkey)
 		{
 		OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ERR_R_PASSED_NULL_PARAMETER);
-		return 1;
+		return 0;
 		}
 
 	EVP_MD_CTX_init(&ctx);
 
-	/* Convert signature OID into digest and public key OIDs */
-	if (!OBJ_find_sigid_algs(OBJ_obj2nid(a->algorithm), &mdnid, &pknid))
+	if (!EVP_DigestVerifyInitFromAlgorithm(&ctx, a, pkey))
 		{
-		OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ASN1_R_UNKNOWN_SIGNATURE_ALGORITHM);
 		goto err;
 		}
-	if (mdnid == NID_undef)
-		{
-		if (!pkey->ameth || !pkey->ameth->item_verify)
-			{
-			OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ASN1_R_UNKNOWN_SIGNATURE_ALGORITHM);
-			goto err;
-			}
-		ret = pkey->ameth->item_verify(&ctx, it, asn, a,
-							signature, pkey);
-		/* Return value of 2 means carry on, anything else means we
-		 * exit straight away: either a fatal error of the underlying
-		 * verification routine handles all verification.
-		 */
-		if (ret != 2)
-			goto err;
-		ret = -1;
-		}
-	else
-		{
-		const EVP_MD *type;
-		type=EVP_get_digestbynid(mdnid);
-		if (type == NULL)
-			{
-			OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ASN1_R_UNKNOWN_MESSAGE_DIGEST_ALGORITHM);
-			goto err;
-			}
-
-		/* Check public key OID matches public key type */
-		ameth = EVP_PKEY_asn1_find(NULL, pknid);
-		if (ameth == NULL || ameth->pkey_id != pkey->ameth->pkey_id)
-			{
-			OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ASN1_R_WRONG_PUBLIC_KEY_TYPE);
-			goto err;
-			}
-
-		if (!EVP_DigestVerifyInit(&ctx, NULL, type, NULL, pkey))
-			{
-			OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ERR_R_EVP_LIB);
-			ret=0;
-			goto err;
-			}
-
-		}
 
 	inl = ASN1_item_i2d(asn, &buf_in, it);
 	
@@ -152,7 +104,6 @@ int ASN1_item_verify(const ASN1_ITEM *it, X509_ALGOR *a,
 		OPENSSL_cleanse(buf_in,(unsigned int)inl);
 		OPENSSL_free(buf_in);
 		OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ERR_R_EVP_LIB);
-		ret=0;
 		goto err;
 		}
 
@@ -163,15 +114,14 @@ int ASN1_item_verify(const ASN1_ITEM *it, X509_ALGOR *a,
 			(size_t)signature->length) <= 0)
 		{
 		OPENSSL_PUT_ERROR(X509, ASN1_item_verify, ERR_R_EVP_LIB);
-		ret=0;
 		goto err;
 		}
 	/* we don't need to zero the 'ctx' because we just checked
 	 * public information */
 	/* memset(&ctx,0,sizeof(ctx)); */
-	ret=1;
+	ret = 1;
 err:
 	EVP_MD_CTX_cleanup(&ctx);
-	return(ret);
+	return ret;
 	}