Add support for ECDH KARI.
authorDr. Stephen Henson <steve@openssl.org>
Wed, 17 Jul 2013 14:13:37 +0000 (15:13 +0100)
committerDr. Stephen Henson <steve@openssl.org>
Wed, 17 Jul 2013 20:45:01 +0000 (21:45 +0100)
Add support for ECDH in enveloped data. The CMS ctrls for the EC ASN1
method decode/encode the appropriate parameters from the CMS ASN1 data
and send appropriate data to the EC public key method.

crypto/ec/ec.h
crypto/ec/ec_ameth.c
crypto/ec/ec_err.c
crypto/ec/ec_pmeth.c

index cca4559..fd5be8b 100644 (file)
@@ -1204,6 +1204,7 @@ void ERR_load_EC_strings(void);
 #define EC_R_INVALID_COMPRESSED_POINT                   110
 #define EC_R_INVALID_COMPRESSION_BIT                    109
 #define EC_R_INVALID_CURVE                              141
+#define EC_R_INVALID_DIGEST                             151
 #define EC_R_INVALID_DIGEST_TYPE                        138
 #define EC_R_INVALID_ENCODING                           102
 #define EC_R_INVALID_FIELD                              103
index 0ce4524..ff0870d 100644 (file)
 #ifndef OPENSSL_NO_CMS
 #include <openssl/cms.h>
 #endif
+#include <openssl/asn1t.h>
 #include "asn1_locl.h"
 
+static int ecdh_cms_decrypt(CMS_RecipientInfo *ri);
+static int ecdh_cms_encrypt(CMS_RecipientInfo *ri);
+
 static int eckey_param2type(int *pptype, void **ppval, EC_KEY *ec_key)
        {
        const EC_GROUP  *group;
@@ -612,6 +616,17 @@ static int ec_pkey_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
                        X509_ALGOR_set0(alg2, OBJ_nid2obj(snid), V_ASN1_UNDEF, 0);
                        }
                return 1;
+
+               case ASN1_PKEY_CTRL_CMS_ENVELOPE:
+               if (arg1 == 1)
+                       return ecdh_cms_decrypt(arg2);
+               else if (arg1 == 0)
+                       return ecdh_cms_encrypt(arg2);
+               return -2;
+
+               case ASN1_PKEY_CTRL_CMS_RI_TYPE:
+               *(int *)arg2 = CMS_RECIPINFO_AGREE;
+               return 1;
 #endif
 
                case ASN1_PKEY_CTRL_DEFAULT_MD_NID:
@@ -658,3 +673,365 @@ const EVP_PKEY_ASN1_METHOD eckey_asn1_meth =
        old_ec_priv_decode,
        old_ec_priv_encode
        };
+
+#ifndef OPENSSL_NO_CMS
+
+static int ecdh_cms_set_peerkey(EVP_PKEY_CTX *pctx,
+                               X509_ALGOR *alg, ASN1_BIT_STRING *pubkey)
+       {
+       ASN1_OBJECT *aoid;
+       int atype;
+       void *aval;
+       int rv = 0;
+       EVP_PKEY *pkpeer = NULL;
+       EC_KEY *ecpeer = NULL;
+       const unsigned char *p;
+       int plen;
+       X509_ALGOR_get0(&aoid, &atype, &aval, alg);
+       if (OBJ_obj2nid(aoid) != NID_X9_62_id_ecPublicKey)
+               goto err;
+       /* If absent parameters get group from main key */
+       if (atype == V_ASN1_UNDEF || atype == V_ASN1_NULL)
+               {
+               const EC_GROUP *grp;
+               EVP_PKEY *pk;
+               pk = EVP_PKEY_CTX_get0_pkey(pctx);
+               if (!pk)
+                       goto err;
+               grp = EC_KEY_get0_group(pk->pkey.ec);
+               ecpeer = EC_KEY_new();
+               if (!ecpeer)
+                       goto err;
+               if (!EC_KEY_set_group(ecpeer, grp))
+                       goto err;
+               }
+       else
+               {
+               ecpeer = eckey_type2param(atype, aval);
+               if (!ecpeer)
+                       goto err;
+               }
+       /* We have parameters now set public key */
+       plen = ASN1_STRING_length(pubkey);
+       p = ASN1_STRING_data(pubkey);
+       if (!p || !plen)
+               goto err;
+       if (!o2i_ECPublicKey(&ecpeer, &p, plen))
+               goto err;
+       pkpeer = EVP_PKEY_new();
+       if (!pkpeer)
+               goto err;
+       EVP_PKEY_set1_EC_KEY(pkpeer, ecpeer);
+       if (EVP_PKEY_derive_set_peer(pctx, pkpeer) > 0)
+               rv = 1;
+       err:
+       if (ecpeer)
+               EC_KEY_free(ecpeer);
+       if (pkpeer)
+               EVP_PKEY_free(pkpeer);
+       return rv;
+       }
+/* Set KDF parameters based on KDF NID */
+static int ecdh_cms_set_kdf_param(EVP_PKEY_CTX *pctx, int eckdf_nid)
+       {
+       int kdf_nid, kdfmd_nid, cofactor;
+       const EVP_MD *kdf_md;
+       if (eckdf_nid == NID_undef)
+               return 0;
+
+       /* Lookup KDF type, cofactor mode and digest */
+       if (!OBJ_find_sigid_algs(eckdf_nid, &kdfmd_nid, &kdf_nid))
+               return 0;
+
+       if (kdf_nid == NID_dh_std_kdf)
+               cofactor = 0;
+       else if (kdf_nid == NID_dh_cofactor_kdf)
+               cofactor = 1;
+       else return 0;
+
+       if (EVP_PKEY_CTX_set_ecdh_cofactor_mode(pctx, cofactor) <= 0)
+               return 0;
+
+       if (EVP_PKEY_CTX_set_ecdh_kdf_type(pctx, EVP_PKEY_ECDH_KDF_X9_62) <= 0)
+               return 0;
+
+       kdf_md = EVP_get_digestbynid(kdfmd_nid);
+       if (!kdf_md)
+               return 0;
+
+       if (EVP_PKEY_CTX_set_ecdh_kdf_md(pctx, kdf_md) <= 0)
+               return 0;
+       return 1;
+       }
+
+/* Utilities to encode the ECC_CMS_SharedInfo structure used during key
+ * derivation.
+ */
+
+typedef struct {
+       X509_ALGOR *keyInfo;
+       ASN1_OCTET_STRING *entityUInfo;
+       ASN1_OCTET_STRING *suppPubInfo;
+} ECC_CMS_SharedInfo;
+
+ASN1_SEQUENCE(ECC_CMS_SharedInfo) = {
+  ASN1_SIMPLE(ECC_CMS_SharedInfo, keyInfo, X509_ALGOR),
+  ASN1_EXP_OPT(ECC_CMS_SharedInfo, entityUInfo, ASN1_OCTET_STRING, 0),
+  ASN1_EXP_OPT(ECC_CMS_SharedInfo, suppPubInfo, ASN1_OCTET_STRING, 2),
+} ASN1_SEQUENCE_END(ECC_CMS_SharedInfo)
+
+static int ecdh_cms_set_ukm(EVP_PKEY_CTX *pctx, 
+                                       X509_ALGOR *kekalg, 
+                                       ASN1_OCTET_STRING *ukm,
+                                       int keylen)
+       {
+       union {
+               ECC_CMS_SharedInfo *pecsi;
+               ASN1_VALUE *a;
+       } intsi = {NULL};
+
+       unsigned char *der = NULL;
+       int plen;
+       ASN1_OCTET_STRING oklen;
+       unsigned char kl[4];
+       ECC_CMS_SharedInfo ecsi;
+
+       keylen <<= 3;
+       kl[0] = (keylen >> 24) & 0xff;
+       kl[1] = (keylen >> 16) & 0xff;
+       kl[2] = (keylen >> 8) & 0xff;
+       kl[3] = keylen & 0xff;
+       oklen.length = 4;
+       oklen.data = kl;
+       oklen.type = V_ASN1_OCTET_STRING;
+       oklen.flags = 0;
+       ecsi.keyInfo = kekalg;
+       ecsi.entityUInfo = ukm;
+       ecsi.suppPubInfo = &oklen;
+       intsi.pecsi = &ecsi;
+       plen = ASN1_item_i2d(intsi.a, &der, ASN1_ITEM_rptr(ECC_CMS_SharedInfo));
+       if (!der || !plen)
+               goto err;
+       if (EVP_PKEY_CTX_set0_ecdh_kdf_ukm(pctx, der, plen) <= 0)
+               goto err;
+       return 1;
+       err:
+       if (der)
+               OPENSSL_free(der);
+       return 0;
+       }
+
+static int ecdh_cms_set_shared_info(EVP_PKEY_CTX *pctx, CMS_RecipientInfo *ri)
+       {
+       int rv = 0;
+
+       X509_ALGOR *alg, *kekalg = NULL;
+       ASN1_OCTET_STRING *ukm;
+       const unsigned char *p;
+       int plen, keylen;
+       const EVP_CIPHER *kekcipher;
+       EVP_CIPHER_CTX *kekctx;
+
+       if (!CMS_RecipientInfo_kari_get0_alg(ri, &alg, &ukm))
+               return 0;
+
+       if (!ecdh_cms_set_kdf_param(pctx, OBJ_obj2nid(alg->algorithm)))
+               {
+               ECerr(EC_F_ECDH_CMS_SET_SHARED_INFO, EC_R_KDF_PARAMETER_ERROR);
+               return 0;
+               }
+
+       if (alg->parameter->type != V_ASN1_SEQUENCE)
+               return 0;
+
+       p = alg->parameter->value.sequence->data;
+       plen = alg->parameter->value.sequence->length;
+       kekalg = d2i_X509_ALGOR(NULL, &p, plen);
+       if (!kekalg)
+               goto err;
+       kekctx = CMS_RecipientInfo_kari_get0_ctx(ri);
+       if (!kekctx)
+               goto err;
+       kekcipher = EVP_get_cipherbyobj(kekalg->algorithm);
+       if (!kekcipher || EVP_CIPHER_mode(kekcipher) != EVP_CIPH_WRAP_MODE)
+               goto err;
+       if (!EVP_EncryptInit_ex(kekctx, kekcipher, NULL, NULL, NULL))
+               goto err;
+
+       keylen = EVP_CIPHER_CTX_key_length(kekctx);
+       if (EVP_PKEY_CTX_set_ecdh_kdf_outlen(pctx, keylen) <= 0)
+               goto err;
+
+       if (!ecdh_cms_set_ukm(pctx, kekalg, ukm, keylen))
+               goto err;
+
+       rv = 1;
+       err:
+       if (kekalg)
+               X509_ALGOR_free(kekalg);
+       return rv;
+       }
+
+static int ecdh_cms_decrypt(CMS_RecipientInfo *ri)
+       {
+       EVP_PKEY_CTX *pctx;
+       pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
+       if (!pctx)
+               return 0;
+       /* See if we need to set peer key */
+       if (!EVP_PKEY_CTX_get0_peerkey(pctx))
+               {
+               X509_ALGOR *alg;
+               ASN1_BIT_STRING *pubkey;
+               if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &alg, &pubkey,
+                                                       NULL, NULL, NULL))
+                       return 0;
+               if (!alg || !pubkey)
+                       return 0;
+               if (!ecdh_cms_set_peerkey(pctx, alg, pubkey))
+                       {
+                       ECerr(EC_F_ECDH_CMS_DECRYPT, EC_R_PEER_KEY_ERROR);
+                       return 0;
+                       }
+               }
+       /* Set ECDH derivation parameters and initialise unwrap context */
+       if (!ecdh_cms_set_shared_info(pctx, ri))
+               {
+               ECerr(EC_F_ECDH_CMS_DECRYPT, EC_R_SHARED_INFO_ERROR);
+               return 0;
+               }
+       return 1;
+       }
+
+static int ecdh_cms_encrypt(CMS_RecipientInfo *ri)
+       {
+       EVP_PKEY_CTX *pctx;
+       EVP_PKEY *pkey;
+       EVP_CIPHER_CTX *ctx;
+       int keylen;
+       X509_ALGOR *talg, *wrap_alg = NULL;
+       ASN1_OBJECT *aoid;
+       ASN1_BIT_STRING *pubkey;
+       ASN1_STRING *wrap_str;
+       ASN1_OCTET_STRING *ukm;
+       unsigned char *penc = NULL;
+       int penclen;
+       int rv = 0;
+       int ecdh_nid, kdf_type, kdf_nid, wrap_nid;
+       const EVP_MD *kdf_md;
+       pctx = CMS_RecipientInfo_get0_pkey_ctx(ri);
+       if (!pctx)
+               return 0;
+       /* Get ephemeral key */
+       pkey = EVP_PKEY_CTX_get0_pkey(pctx);
+       if (!CMS_RecipientInfo_kari_get0_orig_id(ri, &talg, &pubkey,
+                                                       NULL, NULL, NULL))
+               goto err;
+       X509_ALGOR_get0(&aoid, NULL, NULL, talg);
+       /* Is everything uninitialised? */
+       if (aoid == OBJ_nid2obj(NID_undef))
+               {
+
+               EC_KEY *eckey = pkey->pkey.ec;
+               /* Set the key */
+               unsigned char *p;
+
+               penclen = i2o_ECPublicKey(eckey, NULL);
+               if (penclen <= 0)
+                       goto err;
+               penc = OPENSSL_malloc(penclen);
+               if (!penc)
+                       goto err;
+               p = penc;
+               penclen = i2o_ECPublicKey(eckey, &p);
+               if (penclen <= 0)
+                       goto err;
+               ASN1_STRING_set0(pubkey, penc, penclen);
+               pubkey->flags&= ~(ASN1_STRING_FLAG_BITS_LEFT|0x07);
+               pubkey->flags|=ASN1_STRING_FLAG_BITS_LEFT;
+
+               penc = NULL;
+               X509_ALGOR_set0(talg, OBJ_nid2obj(NID_X9_62_id_ecPublicKey),
+                                                       V_ASN1_UNDEF, NULL);
+               }
+
+       /* See if custom paraneters set */
+       kdf_type = EVP_PKEY_CTX_get_ecdh_kdf_type(pctx);
+       if (kdf_type <= 0)
+               goto err;
+       if (!EVP_PKEY_CTX_get_ecdh_kdf_md(pctx, &kdf_md))
+               goto err;
+       ecdh_nid = EVP_PKEY_CTX_get_ecdh_cofactor_mode(pctx);
+       if (ecdh_nid < 0)
+               goto err;
+       else if (ecdh_nid == 0)
+               ecdh_nid = NID_dh_std_kdf;
+       else if (ecdh_nid == 1)
+               ecdh_nid = NID_dh_cofactor_kdf;
+
+       if (kdf_type == EVP_PKEY_ECDH_KDF_NONE)
+               {
+               kdf_type = EVP_PKEY_ECDH_KDF_X9_62;
+               if (EVP_PKEY_CTX_set_ecdh_kdf_type(pctx, kdf_type) <= 0)
+                       goto err;
+               }
+       else
+               /* Uknown KDF */
+               goto err;
+       if (kdf_md == NULL)
+               {
+               /* Fixme later for better MD */
+               kdf_md = EVP_sha1();
+               if (EVP_PKEY_CTX_set_ecdh_kdf_md(pctx, kdf_md) <= 0)
+                       goto err;
+               }
+
+       if (!CMS_RecipientInfo_kari_get0_alg(ri, &talg, &ukm))
+               goto err;
+
+       /* Lookup NID for KDF+cofactor+digest */
+
+       if (!OBJ_find_sigid_by_algs(&kdf_nid, EVP_MD_type(kdf_md), ecdh_nid))
+               goto err;
+       /* Get wrap NID */
+       ctx = CMS_RecipientInfo_kari_get0_ctx(ri);
+       wrap_nid = EVP_CIPHER_CTX_type(ctx);
+       keylen = EVP_CIPHER_CTX_key_length(ctx);
+
+       /* Package wrap algorithm in an AlgorithmIdentifier */
+
+       wrap_alg = X509_ALGOR_new();
+       if (!wrap_alg)
+               goto err;
+       X509_ALGOR_set0(wrap_alg, OBJ_nid2obj(wrap_nid), V_ASN1_UNDEF, NULL);
+
+       if (EVP_PKEY_CTX_set_ecdh_kdf_outlen(pctx, keylen) <= 0)
+               goto err;
+       if (!ecdh_cms_set_ukm(pctx, wrap_alg, ukm, keylen))
+               goto err;
+
+       /* Now need to wrap encoding of wrap AlgorithmIdentifier into
+        * parameter of another AlgorithmIdentifier.
+        */
+       penc = NULL;
+       penclen = i2d_X509_ALGOR(wrap_alg, &penc);
+       if (!penc || !penclen)
+               goto err;
+       wrap_str = ASN1_STRING_new();
+       if (!wrap_str)
+               goto err;
+       ASN1_STRING_set0(wrap_str, penc, penclen);
+       penc = NULL;
+       X509_ALGOR_set0(talg, OBJ_nid2obj(kdf_nid), V_ASN1_SEQUENCE, wrap_str);
+
+       rv = 1;
+
+       err:
+       if (penc)
+               OPENSSL_free(penc);
+       if (wrap_alg)
+               X509_ALGOR_free(wrap_alg);
+       return rv;
+       }
+
+#endif
index 0d19398..b7e1874 100644 (file)
@@ -1,6 +1,6 @@
 /* crypto/ec/ec_err.c */
 /* ====================================================================
- * Copyright (c) 1999-2011 The OpenSSL Project.  All rights reserved.
+ * Copyright (c) 1999-2013 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -76,6 +76,8 @@ static ERR_STRING_DATA EC_str_functs[]=
 {ERR_FUNC(EC_F_D2I_ECPKPARAMETERS),    "d2i_ECPKParameters"},
 {ERR_FUNC(EC_F_D2I_ECPRIVATEKEY),      "d2i_ECPrivateKey"},
 {ERR_FUNC(EC_F_DO_EC_KEY_PRINT),       "DO_EC_KEY_PRINT"},
+{ERR_FUNC(EC_F_ECDH_CMS_DECRYPT),      "ECDH_CMS_DECRYPT"},
+{ERR_FUNC(EC_F_ECDH_CMS_SET_SHARED_INFO),      "ECDH_CMS_SET_SHARED_INFO"},
 {ERR_FUNC(EC_F_ECKEY_PARAM2TYPE),      "ECKEY_PARAM2TYPE"},
 {ERR_FUNC(EC_F_ECKEY_PARAM_DECODE),    "ECKEY_PARAM_DECODE"},
 {ERR_FUNC(EC_F_ECKEY_PRIV_DECODE),     "ECKEY_PRIV_DECODE"},
@@ -229,6 +231,7 @@ static ERR_STRING_DATA EC_str_reasons[]=
 {ERR_REASON(EC_R_INVALID_COMPRESSED_POINT),"invalid compressed point"},
 {ERR_REASON(EC_R_INVALID_COMPRESSION_BIT),"invalid compression bit"},
 {ERR_REASON(EC_R_INVALID_CURVE)          ,"invalid curve"},
+{ERR_REASON(EC_R_INVALID_DIGEST)         ,"invalid digest"},
 {ERR_REASON(EC_R_INVALID_DIGEST_TYPE)    ,"invalid digest type"},
 {ERR_REASON(EC_R_INVALID_ENCODING)       ,"invalid encoding"},
 {ERR_REASON(EC_R_INVALID_FIELD)          ,"invalid field"},
@@ -237,6 +240,7 @@ static ERR_STRING_DATA EC_str_reasons[]=
 {ERR_REASON(EC_R_INVALID_PENTANOMIAL_BASIS),"invalid pentanomial basis"},
 {ERR_REASON(EC_R_INVALID_PRIVATE_KEY)    ,"invalid private key"},
 {ERR_REASON(EC_R_INVALID_TRINOMIAL_BASIS),"invalid trinomial basis"},
+{ERR_REASON(EC_R_KDF_PARAMETER_ERROR)    ,"kdf parameter error"},
 {ERR_REASON(EC_R_KEYS_NOT_SET)           ,"keys not set"},
 {ERR_REASON(EC_R_MISSING_PARAMETERS)     ,"missing parameters"},
 {ERR_REASON(EC_R_MISSING_PRIVATE_KEY)    ,"missing private key"},
@@ -247,9 +251,11 @@ static ERR_STRING_DATA EC_str_reasons[]=
 {ERR_REASON(EC_R_NO_FIELD_MOD)           ,"no field mod"},
 {ERR_REASON(EC_R_NO_PARAMETERS_SET)      ,"no parameters set"},
 {ERR_REASON(EC_R_PASSED_NULL_PARAMETER)  ,"passed null parameter"},
+{ERR_REASON(EC_R_PEER_KEY_ERROR)         ,"peer key error"},
 {ERR_REASON(EC_R_PKPARAMETERS2GROUP_FAILURE),"pkparameters2group failure"},
 {ERR_REASON(EC_R_POINT_AT_INFINITY)      ,"point at infinity"},
 {ERR_REASON(EC_R_POINT_IS_NOT_ON_CURVE)  ,"point is not on curve"},
+{ERR_REASON(EC_R_SHARED_INFO_ERROR)      ,"shared info error"},
 {ERR_REASON(EC_R_SLOT_FULL)              ,"slot full"},
 {ERR_REASON(EC_R_UNDEFINED_GENERATOR)    ,"undefined generator"},
 {ERR_REASON(EC_R_UNDEFINED_ORDER)        ,"undefined order"},
index 689a173..e477418 100644 (file)
@@ -319,7 +319,7 @@ static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
                case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
                if (p1 == -2)
                        {
-                       if (dctx->co_key)
+                       if (dctx->cofactor_mode != -1)
                                return dctx->cofactor_mode;
                        else
                                {
@@ -459,6 +459,22 @@ static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
                        return -2;
                return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
                }
+       else if (!strcmp(type, "ecdh_kdf_md"))
+               {
+               const EVP_MD *md;
+               if (!(md = EVP_get_digestbyname(value)))
+                       {
+                       ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_DIGEST);
+                       return 0;
+                       }
+               return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
+               }
+       else if (!strcmp(type, "ecdh_cofactor_mode"))
+               {
+               int co_mode;
+               co_mode = atoi(value);
+               return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
+               }
                        
        return -2;
        }