updates for draft-ietf-tls-ecc-03.txt

Submitted by: Douglas Stebila
Reviewed by: Bodo Moeller

CHANGES

@@ -4,6 +4,14 @@
 
  Changes between 0.9.7c and 0.9.8  [xx XXX xxxx]
 
+  *) Update support for ECC-based TLS ciphersuites according to
+     draft-ietf-tls-ecc-03.txt: the KDF1 key derivation function with
+     SHA-1 now is only used for "small" curves (where the
+     representation of a field element takes up to 24 bytes); for
+     larger curves, the field element resulting from ECDH is directly
+     used as premaster secret.
+     [Douglas Stebila (Sun Microsystems Laboratories)]
+
   *) Add code for kP+lQ timings to crypto/ec/ectest.c, and add SEC2
      curve secp160r1 to the tests.
      [Douglas Stebila (Sun Microsystems Laboratories)]

apps/speed.c

@@ -2079,12 +2079,28 @@ int MAIN(int argc, char **argv)
 					}
 				else
 					{
-					secret_size_a = ECDH_compute_key(secret_a, KDF1_SHA1_len,
+					/* If field size is not more than 24 octets, then use SHA-1 hash of result;
+					 * otherwise, use result (see section 4.8 of draft-ietf-tls-ecc-03.txt).
+					 */
+					int field_size, outlen;
+					void *(*kdf)(void *in, size_t inlen, void *out, size_t outlen);
+					field_size = EC_GROUP_get_degree(ecdh_a[j]->group);
+					if (field_size <= 24 * 8)
+						{
+						outlen = KDF1_SHA1_len;
+						kdf = KDF1_SHA1;
+						}
+					else
+						{
+						outlen = (field_size+7)/8;
+						kdf = NULL;
+						}
+					secret_size_a = ECDH_compute_key(secret_a, outlen,
 						ecdh_b[j]->pub_key,
-						ecdh_a[j], KDF1_SHA1);
-					secret_size_b = ECDH_compute_key(secret_b, KDF1_SHA1_len,
+						ecdh_a[j], kdf);
+					secret_size_b = ECDH_compute_key(secret_b, outlen,
 						ecdh_a[j]->pub_key,
-						ecdh_b[j], KDF1_SHA1);
+						ecdh_b[j], kdf);
 					if (secret_size_a != secret_size_b) 
 						ecdh_checks = 0;
 					else
@@ -2113,9 +2129,9 @@ int MAIN(int argc, char **argv)
 					Time_F(START);
 					for (count=0,run=1; COND(ecdh_c[j][0]); count++)
 						{
-						ECDH_compute_key(secret_a, KDF1_SHA1_len,
+						ECDH_compute_key(secret_a, outlen,
 						ecdh_b[j]->pub_key,
-						ecdh_a[j], KDF1_SHA1);
+						ecdh_a[j], kdf);
 						}
 					d=Time_F(STOP);
 					BIO_printf(bio_err, mr ? "+R7:%ld:%d:%.2f\n" :"%ld %d-bit ECDH ops in %.2fs\n",

crypto/ec/ec.h

@@ -158,6 +158,7 @@ int EC_GROUP_get_curve_GFp(const EC_GROUP *, BIGNUM *p, BIGNUM *a, BIGNUM *b, BN
 int EC_GROUP_set_curve_GF2m(EC_GROUP *, const BIGNUM *p, const BIGNUM *a, const BIGNUM *b, BN_CTX *);
 int EC_GROUP_get_curve_GF2m(const EC_GROUP *, BIGNUM *p, BIGNUM *a, BIGNUM *b, BN_CTX *);
 
+/* returns the number of bits needed to represent a field element */
 int EC_GROUP_get_degree(const EC_GROUP *);
 
 /* EC_GROUP_check() returns 1 if 'group' defines a valid group, 0 otherwise */

crypto/objects/obj_dat.h

@@ -62,12 +62,12 @@
  * [including the GNU Public Licence.]
  */
 
-#define NUM_NID 721
-#define NUM_SN 716
-#define NUM_LN 716
-#define NUM_OBJ 690
+#define NUM_NID 724
+#define NUM_SN 719
+#define NUM_LN 719
+#define NUM_OBJ 693
 
-static unsigned char lvalues[4879]={
+static unsigned char lvalues[4882]={
 0x00,                                        /* [  0] OBJ_undef */
 0x2A,0x86,0x48,0x86,0xF7,0x0D,               /* [  1] OBJ_rsadsi */
 0x2A,0x86,0x48,0x86,0xF7,0x0D,0x01,          /* [  7] OBJ_pkcs */
@@ -432,7 +432,7 @@ static unsigned char lvalues[4879]={
 0x2B,0x06,0x01,0x04,0x01,0x8B,0x3A,0x82,0x58,/* [2865] OBJ_dcObject */
 0x09,0x92,0x26,0x89,0x93,0xF2,0x2C,0x64,0x01,0x19,/* [2874] OBJ_domainComponent */
 0x09,0x92,0x26,0x89,0x93,0xF2,0x2C,0x64,0x04,0x0D,/* [2884] OBJ_Domain */
-0x50,                                        /* [2894] OBJ_joint_iso_ccitt */
+0x00,                                        /* [2894] OBJ_joint_iso_ccitt */
 0x55,0x01,0x05,                              /* [2895] OBJ_selected_attribute_types */
 0x55,0x01,0x05,0x37,                         /* [2898] OBJ_clearance */
 0x2A,0x86,0x48,0x86,0xF7,0x0D,0x01,0x01,0x03,/* [2902] OBJ_md4WithRSAEncryption */
@@ -758,6 +758,9 @@ static unsigned char lvalues[4879]={
 0x55,0x1D,0x20,0x00,                         /* [4868] OBJ_any_policy */
 0x55,0x1D,0x21,                              /* [4872] OBJ_policy_mappings */
 0x55,0x1D,0x1E,                              /* [4875] OBJ_name_constraints */
+0x00,                                        /* [4878] OBJ_itu_t */
+0x50,                                        /* [4879] OBJ_joint_iso_itu_t */
+0x67,                                        /* [4880] OBJ_international_organizations */
 };
 
 static ASN1_OBJECT nid_objs[NUM_NID]={
@@ -1370,8 +1373,7 @@ static ASN1_OBJECT nid_objs[NUM_NID]={
 {"dcobject","dcObject",NID_dcObject,9,&(lvalues[2865]),0},
 {"DC","domainComponent",NID_domainComponent,10,&(lvalues[2874]),0},
 {"domain","Domain",NID_Domain,10,&(lvalues[2884]),0},
-{"JOINT-ISO-CCITT","joint-iso-ccitt",NID_joint_iso_ccitt,1,
-	&(lvalues[2894]),0},
+{"NULL","NULL",NID_joint_iso_ccitt,1,&(lvalues[2894]),0},
 {"selected-attribute-types","Selected Attribute Types",
 	NID_selected_attribute_types,3,&(lvalues[2895]),0},
 {"clearance","clearance",NID_clearance,4,&(lvalues[2898]),0},
@@ -1389,7 +1391,7 @@ static ASN1_OBJECT nid_objs[NUM_NID]={
 	&(lvalues[2941]),0},
 {"noRevAvail","X509v3 No Revocation Available",NID_no_rev_avail,3,
 	&(lvalues[2944]),0},
-{"CCITT","ccitt",NID_ccitt,1,&(lvalues[2947]),0},
+{"NULL","NULL",NID_ccitt,1,&(lvalues[2947]),0},
 {"ansi-X9-62","ANSI X9.62",NID_ansi_X9_62,5,&(lvalues[2948]),0},
 {"prime-field","prime-field",NID_X9_62_prime_field,7,&(lvalues[2953]),0},
 {"characteristic-two-field","characteristic-two-field",
@@ -1887,6 +1889,11 @@ static ASN1_OBJECT nid_objs[NUM_NID]={
 	&(lvalues[4872]),0},
 {"nameConstraints","X509v3 Name Constraints",NID_name_constraints,3,
 	&(lvalues[4875]),0},
+{"ITU-T","itu-t",NID_itu_t,1,&(lvalues[4878]),0},
+{"JOINT-ISO-ITU-T","joint-iso-itu-t",NID_joint_iso_itu_t,1,
+	&(lvalues[4879]),0},
+{"international-organizations","International Organizations",
+	NID_international_organizations,1,&(lvalues[4880]),0},
 };
 
 static ASN1_OBJECT *sn_objs[NUM_SN]={
@@ -1912,7 +1919,6 @@ static ASN1_OBJECT *sn_objs[NUM_SN]={
 &(nid_objs[110]),/* "CAST5-CFB" */
 &(nid_objs[109]),/* "CAST5-ECB" */
 &(nid_objs[111]),/* "CAST5-OFB" */
-&(nid_objs[404]),/* "CCITT" */
 &(nid_objs[13]),/* "CN" */
 &(nid_objs[141]),/* "CRLReason" */
 &(nid_objs[417]),/* "CSPName" */
@@ -1947,7 +1953,8 @@ static ASN1_OBJECT *sn_objs[NUM_SN]={
 &(nid_objs[46]),/* "IDEA-OFB" */
 &(nid_objs[181]),/* "ISO" */
 &(nid_objs[183]),/* "ISO-US" */
-&(nid_objs[393]),/* "JOINT-ISO-CCITT" */
+&(nid_objs[721]),/* "ITU-T" */
+&(nid_objs[722]),/* "JOINT-ISO-ITU-T" */
 &(nid_objs[15]),/* "L" */
 &(nid_objs[ 3]),/* "MD2" */
 &(nid_objs[257]),/* "MD4" */
@@ -1955,6 +1962,8 @@ static ASN1_OBJECT *sn_objs[NUM_SN]={
 &(nid_objs[114]),/* "MD5-SHA1" */
 &(nid_objs[95]),/* "MDC2" */
 &(nid_objs[388]),/* "Mail" */
+&(nid_objs[393]),/* "NULL" */
+&(nid_objs[404]),/* "NULL" */
 &(nid_objs[57]),/* "Netscape" */
 &(nid_objs[366]),/* "Nonce" */
 &(nid_objs[17]),/* "O" */
@@ -2291,6 +2300,7 @@ static ASN1_OBJECT *sn_objs[NUM_SN]={
 &(nid_objs[527]),/* "identified-organization" */
 &(nid_objs[461]),/* "info" */
 &(nid_objs[101]),/* "initials" */
+&(nid_objs[723]),/* "international-organizations" */
 &(nid_objs[142]),/* "invalidityDate" */
 &(nid_objs[294]),/* "ipsecEndSystem" */
 &(nid_objs[295]),/* "ipsecTunnel" */
@@ -2634,6 +2644,7 @@ static ASN1_OBJECT *ln_objs[NUM_LN]={
 &(nid_objs[296]),/* "IPSec User" */
 &(nid_objs[182]),/* "ISO Member Body" */
 &(nid_objs[183]),/* "ISO US Member Body" */
+&(nid_objs[723]),/* "International Organizations" */
 &(nid_objs[142]),/* "Invalidity Date" */
 &(nid_objs[569]),/* "MIME MHS" */
 &(nid_objs[388]),/* "Mail" */
@@ -2647,6 +2658,8 @@ static ASN1_OBJECT *ln_objs[NUM_LN]={
 &(nid_objs[716]),/* "Microsoft Smartcardlogin" */
 &(nid_objs[136]),/* "Microsoft Trust List Signing" */
 &(nid_objs[717]),/* "Microsoft Universal Principal Name" */
+&(nid_objs[393]),/* "NULL" */
+&(nid_objs[404]),/* "NULL" */
 &(nid_objs[72]),/* "Netscape Base Url" */
 &(nid_objs[76]),/* "Netscape CA Policy Url" */
 &(nid_objs[74]),/* "Netscape CA Revocation Url" */
@@ -2765,7 +2778,6 @@ static ASN1_OBJECT *ln_objs[NUM_LN]={
 &(nid_objs[110]),/* "cast5-cfb" */
 &(nid_objs[109]),/* "cast5-ecb" */
 &(nid_objs[111]),/* "cast5-ofb" */
-&(nid_objs[404]),/* "ccitt" */
 &(nid_objs[152]),/* "certBag" */
 &(nid_objs[528]),/* "certicom-arc" */
 &(nid_objs[581]),/* "certificate extensions" */
@@ -3015,8 +3027,9 @@ static ASN1_OBJECT *ln_objs[NUM_LN]={
 &(nid_objs[101]),/* "initials" */
 &(nid_objs[181]),/* "iso" */
 &(nid_objs[687]),/* "issuer capabilities" */
+&(nid_objs[721]),/* "itu-t" */
 &(nid_objs[492]),/* "janetMailbox" */
-&(nid_objs[393]),/* "joint-iso-ccitt" */
+&(nid_objs[722]),/* "joint-iso-itu-t" */
 &(nid_objs[150]),/* "keyBag" */
 &(nid_objs[477]),/* "lastModifiedBy" */
 &(nid_objs[476]),/* "lastModifiedTime" */
@@ -3329,14 +3342,17 @@ static ASN1_OBJECT *ln_objs[NUM_LN]={
 
 static ASN1_OBJECT *obj_objs[NUM_OBJ]={
 &(nid_objs[ 0]),/* OBJ_undef                        0 */
-&(nid_objs[404]),/* OBJ_ccitt                        0 */
+&(nid_objs[721]),/* OBJ_itu_t                        0 */
+&(nid_objs[393]),/* OBJ_joint_iso_ccitt              OBJ_joint_iso_itu_t */
+&(nid_objs[404]),/* OBJ_ccitt                        OBJ_itu_t */
 &(nid_objs[434]),/* OBJ_data                         0 9 */
 &(nid_objs[181]),/* OBJ_iso                          1 */
 &(nid_objs[182]),/* OBJ_member_body                  1 2 */
 &(nid_objs[379]),/* OBJ_org                          1 3 */
 &(nid_objs[527]),/* OBJ_identified_organization      1 3 */
-&(nid_objs[393]),/* OBJ_joint_iso_ccitt              2 */
+&(nid_objs[722]),/* OBJ_joint_iso_itu_t              2 */
 &(nid_objs[11]),/* OBJ_X500                         2 5 */
+&(nid_objs[723]),/* OBJ_international_organizations  2 23 */
 &(nid_objs[380]),/* OBJ_dod                          1 3 6 */
 &(nid_objs[12]),/* OBJ_X509                         2 5 4 */
 &(nid_objs[378]),/* OBJ_X500algorithms               2 5 8 */

demos/ssltest-ecc/README

 Scripts for using ECC ciphersuites with test/testssl
 (these ciphersuites are described in the Internet Draft available at
-http://www.ietf.org/internet-drafts/draft-ietf-tls-ecc-02.txt).
+http://www.ietf.org/internet-drafts/draft-ietf-tls-ecc-03.txt).
 
 Use ECCcertgen.sh, RSAcertgen.sh, ECC-RSAcertgen.sh to generate
 root, client and server certs of the following types:

ssl/s3_clnt.c

@@ -1870,6 +1870,7 @@ static int ssl3_send_client_key_exchange(SSL *s)
 			{
 			EC_GROUP *srvr_group = NULL;
 			int ecdh_clnt_cert = 0;
+			int field_size = 0;
 
 			/* Did we send out the client's
 			 * ECDH share for use in premaster
@@ -1962,7 +1963,21 @@ static int ssl3_send_client_key_exchange(SSL *s)
 			 * make sure to clear it out afterwards
 			 */
 
-			n=ECDH_compute_key(p, KDF1_SHA1_len, srvr_ecpoint, clnt_ecdh, KDF1_SHA1);
+			field_size = EC_GROUP_get_degree(clnt_ecdh->group);
+			if (field_size <= 0)
+				{
+				SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE, 
+				       ERR_R_ECDH_LIB);
+				goto err;
+				}
+			/* If field size is not more than 24 octets, then use SHA-1 hash of result;
+			 * otherwise, use result (see section 4.8 of draft-ietf-tls-ecc-03.txt;
+			 * this is new with this version of the Internet Draft).
+			 */
+			if (field_size <= 24 * 8)
+				n=ECDH_compute_key(p, KDF1_SHA1_len, srvr_ecpoint, clnt_ecdh, KDF1_SHA1);
+			else
+				n=ECDH_compute_key(p, (field_size+7)/8, srvr_ecpoint, clnt_ecdh, NULL);
 			if (n <= 0)
 				{
 				SSLerr(SSL_F_SSL3_SEND_CLIENT_KEY_EXCHANGE, 
@@ -2375,7 +2390,8 @@ err:
 /* This is the complement of nid2curve_id in s3_srvr.c. */
 static int curve_id2nid(int curve_id)
 {
-	/* ECC curves from draft-ietf-tls-ecc-01.txt (Mar 15, 2001) */
+	/* ECC curves from draft-ietf-tls-ecc-01.txt (Mar 15, 2001)
+	 * (no changes in draft-ietf-tls-ecc-03.txt [June 2003]) */
 	static int nid_list[26] =
 	{
 		0,

ssl/s3_srvr.c

@@ -1962,6 +1962,7 @@ static int ssl3_get_client_key_exchange(SSL *s)
 		if ((l & SSL_kECDH) || (l & SSL_kECDHE))
 		{
 		int ret = 1;
+		int field_size = 0;
 
                 /* initialize structures for server's ECDH key pair */
 		if ((srvr_ecdh = EC_KEY_new()) == NULL) 
@@ -2062,7 +2063,21 @@ static int ssl3_get_client_key_exchange(SSL *s)
                         }
 
 		/* Compute the shared pre-master secret */
-                i = ECDH_compute_key(p, KDF1_SHA1_len, clnt_ecpoint, srvr_ecdh, KDF1_SHA1);
+		field_size = EC_GROUP_get_degree(srvr_ecdh->group);
+		if (field_size <= 0)
+			{
+			SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE, 
+			       ERR_R_ECDH_LIB);
+			goto err;
+			}
+		/* If field size is not more than 24 octets, then use SHA-1 hash of result;
+		 * otherwise, use result (see section 4.8 of draft-ietf-tls-ecc-03.txt;
+		 * this is new with this version of the Internet Draft).
+		 */
+		if (field_size <= 24 * 8)
+		    i = ECDH_compute_key(p, KDF1_SHA1_len, clnt_ecpoint, srvr_ecdh, KDF1_SHA1);
+		else
+		    i = ECDH_compute_key(p, (field_size+7)/8, clnt_ecpoint, srvr_ecdh, NULL);
                 if (i <= 0)
                         {
                         SSLerr(SSL_F_SSL3_GET_CLIENT_KEY_EXCHANGE,
@@ -2459,7 +2474,8 @@ int ssl3_send_server_certificate(SSL *s)
 /* This is the complement of curve_id2nid in s3_clnt.c. */
 static int nid2curve_id(int nid)
 {
-	/* ECC curves from draft-ietf-tls-ecc-01.txt (Mar 15, 2001) */
+	/* ECC curves from draft-ietf-tls-ecc-01.txt (Mar 15, 2001)
+	 * (no changes in draft-ietf-tls-ecc-03.txt [June 2003]) */
 	switch (nid) {
 	case NID_sect163k1: /* sect163k1 (1) */
 		return 1;

ssl/tls1.h

@@ -131,6 +131,10 @@ extern "C" {
  * suites to use 5B and 5C instead (this may change with future
  * updates to the IETF draft).
  */
+/* draft-ietf-tls-ecc-03.txt (June 2003) gives a changed list of
+ * ciphersuites, but does not define numbers for all of them
+ * because of possible conflicts with other Internet Drafts;
+ * most numbers are still subject to change. */
 #define TLS1_CK_ECDH_ECDSA_WITH_NULL_SHA                0x03000047
 #define TLS1_CK_ECDH_ECDSA_WITH_RC4_128_SHA             0x03000048
 #define TLS1_CK_ECDH_ECDSA_WITH_DES_CBC_SHA             0x03000049