Add support for X9.62 KDF.
[openssl.git] / crypto / ec / ec_pmeth.c
index 4110d5e..689a173 100644 (file)
@@ -60,6 +60,7 @@
 #include <openssl/asn1t.h>
 #include <openssl/x509.h>
 #include <openssl/ec.h>
+#include "ec_lcl.h"
 #include <openssl/ecdsa.h>
 #include <openssl/evp.h>
 #include "evp_locl.h"
@@ -72,6 +73,20 @@ typedef struct
        EC_GROUP *gen_group;
        /* message digest */
        const EVP_MD *md;
+       /* Duplicate key if custom cofactor needed */
+       EC_KEY *co_key;
+       /* Cofactor mode */
+       char cofactor_mode;
+       /* KDF (if any) to use for ECDH */
+       char kdf_type;
+       /* Message digest to use for key derivation */
+       const EVP_MD *kdf_md;
+       /* User key material */
+       unsigned char *kdf_ukm;
+       size_t kdf_ukmlen;
+       /* KDF output length */
+       size_t kdf_outlen;
+
        } EC_PKEY_CTX;
 
 static int pkey_ec_init(EVP_PKEY_CTX *ctx)
@@ -83,6 +98,14 @@ static int pkey_ec_init(EVP_PKEY_CTX *ctx)
        dctx->gen_group = NULL;
        dctx->md = NULL;
 
+       dctx->cofactor_mode = -1;
+       dctx->co_key = NULL;
+       dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
+       dctx->kdf_md = NULL;
+       dctx->kdf_outlen = 0;
+       dctx->kdf_ukm = NULL;
+       dctx->kdf_ukmlen = 0;
+
        ctx->data = dctx;
 
        return 1;
@@ -102,6 +125,25 @@ static int pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
                        return 0;
                }
        dctx->md = sctx->md;
+
+       if (sctx->co_key)
+               {
+               dctx->co_key = EC_KEY_dup(sctx->co_key);
+               if (!dctx->co_key)
+                       return 0;
+               }
+       dctx->kdf_type = sctx->kdf_type;
+       dctx->kdf_md = sctx->kdf_md;
+       dctx->kdf_outlen = sctx->kdf_outlen;
+       if (sctx->kdf_ukm)
+               {
+               dctx->kdf_ukm = BUF_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
+               if (!dctx->kdf_ukm)
+                       return 0;
+               }
+       else
+               dctx->kdf_ukm = NULL;
+       dctx->kdf_ukmlen = sctx->kdf_ukmlen;
        return 1;
        }
 
@@ -112,6 +154,10 @@ static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
                {
                if (dctx->gen_group)
                        EC_GROUP_free(dctx->gen_group);
+               if (dctx->co_key)
+                       EC_KEY_free(dctx->co_key);
+               if (dctx->kdf_ukm)
+                       OPENSSL_free(dctx->kdf_ukm);
                OPENSSL_free(dctx);
                }
        }
@@ -172,20 +218,23 @@ static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
        int ret;
        size_t outlen;
        const EC_POINT *pubkey = NULL;
+       EC_KEY *eckey;
+       EC_PKEY_CTX *dctx = ctx->data;
        if (!ctx->pkey || !ctx->peerkey)
                {
                ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
                return 0;
                }
 
+       eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
+
        if (!key)
                {
                const EC_GROUP *group;
-               group = EC_KEY_get0_group(ctx->pkey->pkey.ec);
+               group = EC_KEY_get0_group(eckey);
                *keylen = (EC_GROUP_get_degree(group) + 7)/8;
                return 1;
                }
-
        pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
 
        /* NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is
@@ -194,13 +243,52 @@ static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
 
        outlen = *keylen;
                
-       ret = ECDH_compute_key(key, outlen, pubkey, ctx->pkey->pkey.ec, 0);
+       ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
        if (ret < 0)
                return ret;
        *keylen = ret;
        return 1;
        }
 
+static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
+                               unsigned char *key, size_t *keylen)
+       {
+       EC_PKEY_CTX *dctx = ctx->data;
+       unsigned char *ktmp = NULL;
+       size_t ktmplen;
+       int rv = 0;
+       if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
+               return pkey_ec_derive(ctx, key, keylen);
+       if (!key)
+               {
+               *keylen = dctx->kdf_outlen;
+               return 1;
+               }
+       if (*keylen != dctx->kdf_outlen)
+               return 0;
+       if (!pkey_ec_derive(ctx, NULL, &ktmplen))
+               return 0;
+       ktmp = OPENSSL_malloc(ktmplen);
+       if (!ktmp)
+               return 0;
+       if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
+               goto err;
+       /* Do KDF stuff */
+       if (!ECDH_KDF_X9_62(key, *keylen, ktmp, ktmplen, 
+                               dctx->kdf_ukm, dctx->kdf_ukmlen,
+                               dctx->kdf_md))
+               goto err;
+       rv = 1;
+
+       err:
+       if (ktmp)
+               {
+               OPENSSL_cleanse(ktmp, ktmplen);
+               OPENSSL_free(ktmp);
+               }
+       return rv;
+       }
+
 static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
        {
        EC_PKEY_CTX *dctx = ctx->data;
@@ -228,6 +316,89 @@ static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
                EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
                return 1;
 
+               case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
+               if (p1 == -2)
+                       {
+                       if (dctx->co_key)
+                               return dctx->cofactor_mode;
+                       else
+                               {
+                               EC_KEY *ec_key = ctx->pkey->pkey.ec;
+                               return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
+                               }
+                       }
+               else if (p1 < -1 || p1 > 1)
+                       return -2;
+               dctx->cofactor_mode = p1;
+               if (p1 != -1)
+                       {
+                       EC_KEY *ec_key = ctx->pkey->pkey.ec;
+                       if (!ec_key->group)
+                               return -2;
+                       /* If cofactor is 1 cofactor mode does nothing */
+                       if (BN_is_one(&ec_key->group->cofactor))
+                               return 1;
+                       if (!dctx->co_key)
+                               {
+                               dctx->co_key = EC_KEY_dup(ec_key);
+                               if (!dctx->co_key)
+                                       return 0;
+                               }
+                       if (p1)
+                               EC_KEY_set_flags(dctx->co_key,
+                                                       EC_FLAG_COFACTOR_ECDH);
+                       else
+                               EC_KEY_clear_flags(dctx->co_key,
+                                                       EC_FLAG_COFACTOR_ECDH);
+                       }
+               else if (dctx->co_key)
+                       {
+                       EC_KEY_free(dctx->co_key);
+                       dctx->co_key = NULL;
+                       }
+               return 1;
+
+               case EVP_PKEY_CTRL_EC_KDF_TYPE:
+               if (p1 == -2)
+                       return dctx->kdf_type;
+               if (p1 != EVP_PKEY_ECDH_KDF_NONE &&
+                   p1 != EVP_PKEY_ECDH_KDF_X9_62)
+                       return -2;
+               dctx->kdf_type = p1;
+               return 1;
+
+               case EVP_PKEY_CTRL_EC_KDF_MD:
+               dctx->kdf_md = p2;
+               return 1;
+
+               case EVP_PKEY_CTRL_GET_EC_KDF_MD:
+               *(const EVP_MD **)p2 = dctx->kdf_md;
+               return 1;
+
+               case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
+               if (p1 <= 0)
+                       return -2;
+               dctx->kdf_outlen = (size_t)p1;
+               return 1;
+
+               case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
+               *(int *)p2 = dctx->kdf_outlen;
+               return 1;
+
+               case EVP_PKEY_CTRL_EC_KDF_UKM:
+               if (dctx->kdf_ukm)
+                       OPENSSL_free(dctx->kdf_ukm);
+               dctx->kdf_ukm = p2;
+               if (p2)
+                       dctx->kdf_ukmlen = p1;
+               else
+                       dctx->kdf_ukmlen = 0;
+               return 1;
+
+               case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
+               *(unsigned char **)p2 = dctx->kdf_ukm;
+               return dctx->kdf_ukmlen;
+
                case EVP_PKEY_CTRL_MD:
                if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
                    EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
@@ -369,7 +540,7 @@ const EVP_PKEY_METHOD ec_pkey_meth =
        0,0,
 
        0,
-       pkey_ec_derive,
+       pkey_ec_kdf_derive,
 
        pkey_ec_ctrl,
        pkey_ec_ctrl_str