From 83cb7c46353b849b9511f1328a06a1ef33baf5c8 Mon Sep 17 00:00:00 2001
From: "Dr. Stephen Henson" <steve@openssl.org>
Date: Wed, 15 Feb 2012 14:04:00 +0000
Subject: [PATCH] An incompatibility has always existed between the format used
 for RSA signatures and MDC2 using EVP or RSA_sign. This has become more
 apparent when the dgst utility in OpenSSL 1.0.0 and later switched to using
 the EVP_DigestSign functions which call RSA_sign.

This means that the signature format OpenSSL 1.0.0 and later used with
dgst -sign and MDC2 is incompatible with previous versions.

Add detection in RSA_verify so either format works.

Note: MDC2 is disabled by default in OpenSSL and very rarely used in practice.
---
 CHANGES               |  7 +++++++
 crypto/rsa/rsa_sign.c | 16 ++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/CHANGES b/CHANGES
index 37124447a9..d4163ca955 100644
--- a/CHANGES
+++ b/CHANGES
@@ -267,6 +267,13 @@
   
  Changes between 1.0.0f and 1.0.1  [xx XXX xxxx]
 
+  *) The format used for MDC2 RSA signatures is inconsistent between EVP
+     and the RSA_sign/RSA_verify functions. This was made more apparent when
+     OpenSSL used RSA_sign/RSA_verify for some RSA signatures in particular
+     those which went through EVP_PKEY_METHOD in 1.0.0 and later. Detect 
+     the correct format in RSA_verify so both forms transparently work.
+     [Steve Henson]
+
   *) Some servers which support TLS 1.0 can choke if we initially indicate
      support for TLS 1.2 and later renegotiate using TLS 1.0 in the RSA
      encrypted premaster secret. As a workaround use the maximum pemitted
diff --git a/crypto/rsa/rsa_sign.c b/crypto/rsa/rsa_sign.c
index 0be4ec7fb0..fa3239ab30 100644
--- a/crypto/rsa/rsa_sign.c
+++ b/crypto/rsa/rsa_sign.c
@@ -182,6 +182,22 @@ int int_rsa_verify(int dtype, const unsigned char *m,
 	i=RSA_public_decrypt((int)siglen,sigbuf,s,rsa,RSA_PKCS1_PADDING);
 
 	if (i <= 0) goto err;
+	/* Oddball MDC2 case: signature can be OCTET STRING.
+	 * check for correct tag and length octets.
+	 */
+	if (dtype == NID_mdc2 && i == 18 && s[0] == 0x04 && s[1] == 0x10)
+		{
+		if (rm)
+			{
+			memcpy(rm, s + 2, 16);
+			*prm_len = 16;
+			ret = 1;
+			}
+		else if(memcmp(m, s + 2, 16))
+			RSAerr(RSA_F_INT_RSA_VERIFY,RSA_R_BAD_SIGNATURE);
+		else
+			ret = 1;
+		}
 
 	/* Special case: SSL signature */
 	if(dtype == NID_md5_sha1) {