From: Dr. Stephen Henson <steve@openssl.org>
Date: Tue, 8 Mar 2011 19:07:26 +0000 (+0000)
Subject: New SP 800-56A compliant version of DH_compute_key().
X-Git-Tag: OpenSSL-fips-2_0-rc1~683
X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=bc91494e064ebdcff68f987947f97e404fbca0b5

New SP 800-56A compliant version of DH_compute_key().
---

diff --git a/crypto/dh/dh.h b/crypto/dh/dh.h
index 084dc08c78..63db8c908b 100644
--- a/crypto/dh/dh.h
+++ b/crypto/dh/dh.h
@@ -202,6 +202,7 @@ int	DH_check(const DH *dh,int *codes);
 int	DH_check_pub_key(const DH *dh,const BIGNUM *pub_key, int *codes);
 int	DH_generate_key(DH *dh);
 int	DH_compute_key(unsigned char *key,const BIGNUM *pub_key,DH *dh);
+int	DH_compute_key_padded(unsigned char *key,const BIGNUM *pub_key,DH *dh);
 DH *	d2i_DHparams(DH **a,const unsigned char **pp, long length);
 int	i2d_DHparams(const DH *a,unsigned char **pp);
 #ifndef OPENSSL_NO_FP_API
diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
index bba83be312..6c7a457267 100644
--- a/crypto/dh/dh_key.c
+++ b/crypto/dh/dh_key.c
@@ -86,6 +86,21 @@ int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
 	return dh->meth->compute_key(key, pub_key, dh);
 	}
 
+int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
+	{
+	int rv, pad;
+	rv = dh->meth->compute_key(key, pub_key, dh);
+	if (rv <= 0)
+		return rv;
+	pad = BN_num_bytes(dh->p) - rv;
+	if (pad > 0)
+		{
+		memmove(key + pad, key, rv);
+		memset(key, 0, pad);
+		}
+	return rv + pad;
+	}
+
 static DH_METHOD dh_ossl = {
 "OpenSSL DH Method",
 generate_key,