providers/implementations/kdfs/tls1_prf.c - third_party/openssl - Git at Google

 /*
  * Copyright 2016-2021 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */

 /*
  * Refer to "The TLS Protocol Version 1.0" Section 5
  * (https://tools.ietf.org/html/rfc2246#section-5) and
  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
  * (https://tools.ietf.org/html/rfc5246#section-5).
  *
  * For TLS v1.0 and TLS v1.1 the TLS PRF algorithm is given by:
  *
  *   PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
  *                              P_SHA-1(S2, label + seed)
  *
  * where P_MD5 and P_SHA-1 are defined by P_<hash>, below, and S1 and S2 are
  * two halves of the secret (with the possibility of one shared byte, in the
  * case where the length of the original secret is odd).  S1 is taken from the
  * first half of the secret, S2 from the second half.
  *
  * For TLS v1.2 the TLS PRF algorithm is given by:
  *
  *   PRF(secret, label, seed) = P_<hash>(secret, label + seed)
  *
  * where hash is SHA-256 for all cipher suites defined in RFC 5246 as well as
  * those published prior to TLS v1.2 while the TLS v1.2 protocol is in effect,
  * unless defined otherwise by the cipher suite.
  *
  * P_<hash> is an expansion function that uses a single hash function to expand
  * a secret and seed into an arbitrary quantity of output:
  *
  *   P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
  *                            HMAC_<hash>(secret, A(2) + seed) +
  *                            HMAC_<hash>(secret, A(3) + seed) + ...
  *
  * where + indicates concatenation.  P_<hash> can be iterated as many times as
  * is necessary to produce the required quantity of data.
  *
  * A(i) is defined as:
  *     A(0) = seed
  *     A(i) = HMAC_<hash>(secret, A(i-1))
  */
 #include <stdio.h>
 #include <stdarg.h>
 #include <string.h>
 #include <openssl/evp.h>
 #include <openssl/kdf.h>
 #include <openssl/core_names.h>
 #include <openssl/params.h>
 #include <openssl/proverr.h>
 #include "internal/cryptlib.h"
 #include "internal/numbers.h"
 #include "crypto/evp.h"
 #include "prov/provider_ctx.h"
 #include "prov/providercommon.h"
 #include "prov/implementations.h"
 #include "prov/provider_util.h"
 #include "internal/e_os.h"

 static OSSL_FUNC_kdf_newctx_fn kdf_tls1_prf_new;
 static OSSL_FUNC_kdf_dupctx_fn kdf_tls1_prf_dup;
 static OSSL_FUNC_kdf_freectx_fn kdf_tls1_prf_free;
 static OSSL_FUNC_kdf_reset_fn kdf_tls1_prf_reset;
 static OSSL_FUNC_kdf_derive_fn kdf_tls1_prf_derive;
 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params;
 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params;
 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_tls1_prf_gettable_ctx_params;
 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_tls1_prf_get_ctx_params;

 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
                         const unsigned char *sec, size_t slen,
                         const unsigned char *seed, size_t seed_len,
                         unsigned char *out, size_t olen);

 #define TLS1_PRF_MAXBUF 1024

 /* TLS KDF kdf context structure */
 typedef struct {
     void *provctx;

     /* MAC context for the main digest */
     EVP_MAC_CTX *P_hash;
     /* MAC context for SHA1 for the MD5/SHA-1 combined PRF */
     EVP_MAC_CTX *P_sha1;

     /* Secret value to use for PRF */
     unsigned char *sec;
     size_t seclen;
     /* Buffer of concatenated seed data */
     unsigned char seed[TLS1_PRF_MAXBUF];
     size_t seedlen;
 } TLS1_PRF;

 static void *kdf_tls1_prf_new(void *provctx)
 {
     TLS1_PRF *ctx;

     if (!ossl_prov_is_running())
         return NULL;

     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
     ctx->provctx = provctx;
     return ctx;
 }

 static void kdf_tls1_prf_free(void *vctx)
 {
     TLS1_PRF *ctx = (TLS1_PRF *)vctx;

     if (ctx != NULL) {
         kdf_tls1_prf_reset(ctx);
         OPENSSL_free(ctx);
     }
 }

 static void kdf_tls1_prf_reset(void *vctx)
 {
     TLS1_PRF *ctx = (TLS1_PRF *)vctx;
     void *provctx = ctx->provctx;

     EVP_MAC_CTX_free(ctx->P_hash);
     EVP_MAC_CTX_free(ctx->P_sha1);
     OPENSSL_clear_free(ctx->sec, ctx->seclen);
     OPENSSL_cleanse(ctx->seed, ctx->seedlen);
     memset(ctx, 0, sizeof(*ctx));
     ctx->provctx = provctx;
 }

 static void *kdf_tls1_prf_dup(void *vctx)
 {
     const TLS1_PRF *src = (const TLS1_PRF *)vctx;
     TLS1_PRF *dest;

     dest = kdf_tls1_prf_new(src->provctx);
     if (dest != NULL) {
         if (src->P_hash != NULL
                     && (dest->P_hash = EVP_MAC_CTX_dup(src->P_hash)) == NULL)
             goto err;
         if (src->P_sha1 != NULL
                     && (dest->P_sha1 = EVP_MAC_CTX_dup(src->P_sha1)) == NULL)
             goto err;
         if (!ossl_prov_memdup(src->sec, src->seclen, &dest->sec, &dest->seclen))
             goto err;
         memcpy(dest->seed, src->seed, src->seedlen);
         dest->seedlen = src->seedlen;
     }
     return dest;

  err:
     kdf_tls1_prf_free(dest);
     return NULL;
 }

 static int kdf_tls1_prf_derive(void *vctx, unsigned char *key, size_t keylen,
                                const OSSL_PARAM params[])
 {
     TLS1_PRF *ctx = (TLS1_PRF *)vctx;

     if (!ossl_prov_is_running() || !kdf_tls1_prf_set_ctx_params(ctx, params))
         return 0;

     if (ctx->P_hash == NULL) {
         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
         return 0;
     }
     if (ctx->sec == NULL) {
         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
         return 0;
     }
     if (ctx->seedlen == 0) {
         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
         return 0;
     }
     if (keylen == 0) {
         ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
         return 0;
     }

     return tls1_prf_alg(ctx->P_hash, ctx->P_sha1,
                         ctx->sec, ctx->seclen,
                         ctx->seed, ctx->seedlen,
                         key, keylen);
 }

 static int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 {
     const OSSL_PARAM *p;
     TLS1_PRF *ctx = vctx;
     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);

     if (params == NULL)
         return 1;

     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
         if (strcasecmp(p->data, SN_md5_sha1) == 0) {
             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
                                                    OSSL_MAC_NAME_HMAC,
                                                    NULL, SN_md5, libctx)
                 || !ossl_prov_macctx_load_from_params(&ctx->P_sha1, params,
                                                       OSSL_MAC_NAME_HMAC,
                                                       NULL, SN_sha1, libctx))
                 return 0;
         } else {
             EVP_MAC_CTX_free(ctx->P_sha1);
             if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
                                                    OSSL_MAC_NAME_HMAC,
                                                    NULL, NULL, libctx))
                 return 0;
         }
     }

     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
         OPENSSL_clear_free(ctx->sec, ctx->seclen);
         ctx->sec = NULL;
         if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
             return 0;
     }
     /* The seed fields concatenate, so process them all */
     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
         for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
                                                       OSSL_KDF_PARAM_SEED)) {
             const void *q = ctx->seed + ctx->seedlen;
             size_t sz = 0;

             if (p->data_size != 0
                 && p->data != NULL
                 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
                                                 TLS1_PRF_MAXBUF - ctx->seedlen,
                                                 &sz))
                 return 0;
             ctx->seedlen += sz;
         }
     }
     return 1;
 }

 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(
         ossl_unused void *ctx, ossl_unused void *provctx)
 {
     static const OSSL_PARAM known_settable_ctx_params[] = {
         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
         OSSL_PARAM_END
     };
     return known_settable_ctx_params;
 }

 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 {
     OSSL_PARAM *p;

     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
         return OSSL_PARAM_set_size_t(p, SIZE_MAX);
     return -2;
 }

 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(
         ossl_unused void *ctx, ossl_unused void *provctx)
 {
     static const OSSL_PARAM known_gettable_ctx_params[] = {
         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
         OSSL_PARAM_END
     };
     return known_gettable_ctx_params;
 }

 const OSSL_DISPATCH ossl_kdf_tls1_prf_functions[] = {
     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_tls1_prf_dup },
     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
     { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
       (void(*)(void))kdf_tls1_prf_settable_ctx_params },
     { OSSL_FUNC_KDF_SET_CTX_PARAMS,
       (void(*)(void))kdf_tls1_prf_set_ctx_params },
     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
       (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
     { OSSL_FUNC_KDF_GET_CTX_PARAMS,
       (void(*)(void))kdf_tls1_prf_get_ctx_params },
     { 0, NULL }
 };

 /*
  * Refer to "The TLS Protocol Version 1.0" Section 5
  * (https://tools.ietf.org/html/rfc2246#section-5) and
  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
  * (https://tools.ietf.org/html/rfc5246#section-5).
  *
  * P_<hash> is an expansion function that uses a single hash function to expand
  * a secret and seed into an arbitrary quantity of output:
  *
  *   P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
  *                            HMAC_<hash>(secret, A(2) + seed) +
  *                            HMAC_<hash>(secret, A(3) + seed) + ...
  *
  * where + indicates concatenation.  P_<hash> can be iterated as many times as
  * is necessary to produce the required quantity of data.
  *
  * A(i) is defined as:
  *     A(0) = seed
  *     A(i) = HMAC_<hash>(secret, A(i-1))
  */
 static int tls1_prf_P_hash(EVP_MAC_CTX *ctx_init,
                            const unsigned char *sec, size_t sec_len,
                            const unsigned char *seed, size_t seed_len,
                            unsigned char *out, size_t olen)
 {
     size_t chunk;
     EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL;
     unsigned char Ai[EVP_MAX_MD_SIZE];
     size_t Ai_len;
     int ret = 0;

     if (!EVP_MAC_init(ctx_init, sec, sec_len, NULL))
         goto err;
     chunk = EVP_MAC_CTX_get_mac_size(ctx_init);
     if (chunk == 0)
         goto err;
     /* A(0) = seed */
     ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
     if (ctx_Ai == NULL)
         goto err;
     if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
         goto err;

     for (;;) {
         /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
         if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
             goto err;
         EVP_MAC_CTX_free(ctx_Ai);
         ctx_Ai = NULL;

         /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
         ctx = EVP_MAC_CTX_dup(ctx_init);
         if (ctx == NULL)
             goto err;
         if (!EVP_MAC_update(ctx, Ai, Ai_len))
             goto err;
         /* save state for calculating next A(i) value */
         if (olen > chunk) {
             ctx_Ai = EVP_MAC_CTX_dup(ctx);
             if (ctx_Ai == NULL)
                 goto err;
         }
         if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
             goto err;
         if (olen <= chunk) {
             /* last chunk - use Ai as temp bounce buffer */
             if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
                 goto err;
             memcpy(out, Ai, olen);
             break;
         }
         if (!EVP_MAC_final(ctx, out, NULL, olen))
             goto err;
         EVP_MAC_CTX_free(ctx);
         ctx = NULL;
         out += chunk;
         olen -= chunk;
     }
     ret = 1;
  err:
     EVP_MAC_CTX_free(ctx);
     EVP_MAC_CTX_free(ctx_Ai);
     OPENSSL_cleanse(Ai, sizeof(Ai));
     return ret;
 }

 /*
  * Refer to "The TLS Protocol Version 1.0" Section 5
  * (https://tools.ietf.org/html/rfc2246#section-5) and
  * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
  * (https://tools.ietf.org/html/rfc5246#section-5).
  *
  * For TLS v1.0 and TLS v1.1:
  *
  *   PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
  *                              P_SHA-1(S2, label + seed)
  *
  * S1 is taken from the first half of the secret, S2 from the second half.
  *
  *   L_S = length in bytes of secret;
  *   L_S1 = L_S2 = ceil(L_S / 2);
  *
  * For TLS v1.2:
  *
  *   PRF(secret, label, seed) = P_<hash>(secret, label + seed)
  */
 static int tls1_prf_alg(EVP_MAC_CTX *mdctx, EVP_MAC_CTX *sha1ctx,
                         const unsigned char *sec, size_t slen,
                         const unsigned char *seed, size_t seed_len,
                         unsigned char *out, size_t olen)
 {
     if (sha1ctx != NULL) {
         /* TLS v1.0 and TLS v1.1 */
         size_t i;
         unsigned char *tmp;
         /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
         size_t L_S1 = (slen + 1) / 2;
         size_t L_S2 = L_S1;

         if (!tls1_prf_P_hash(mdctx, sec, L_S1,
                              seed, seed_len, out, olen))
             return 0;

         if ((tmp = OPENSSL_malloc(olen)) == NULL) {
             ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
             return 0;
         }

         if (!tls1_prf_P_hash(sha1ctx, sec + slen - L_S2, L_S2,
                              seed, seed_len, tmp, olen)) {
             OPENSSL_clear_free(tmp, olen);
             return 0;
         }
         for (i = 0; i < olen; i++)
             out[i] ^= tmp[i];
         OPENSSL_clear_free(tmp, olen);
         return 1;
     }

     /* TLS v1.2 */
     if (!tls1_prf_P_hash(mdctx, sec, slen, seed, seed_len, out, olen))
         return 0;

     return 1;
 }
	/*
	* Copyright 2016-2021 The OpenSSL Project Authors. All Rights Reserved.
	*
	* Licensed under the Apache License 2.0 (the "License"). You may not use
	* this file except in compliance with the License. You can obtain a copy
	* in the file LICENSE in the source distribution or at
	* https://www.openssl.org/source/license.html
	*/

	/*
	* Refer to "The TLS Protocol Version 1.0" Section 5
	* (https://tools.ietf.org/html/rfc2246#section-5) and
	* "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
	* (https://tools.ietf.org/html/rfc5246#section-5).
	*
	* For TLS v1.0 and TLS v1.1 the TLS PRF algorithm is given by:
	*
	* PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
	* P_SHA-1(S2, label + seed)
	*
	* where P_MD5 and P_SHA-1 are defined by P_<hash>, below, and S1 and S2 are
	* two halves of the secret (with the possibility of one shared byte, in the
	* case where the length of the original secret is odd). S1 is taken from the
	* first half of the secret, S2 from the second half.
	*
	* For TLS v1.2 the TLS PRF algorithm is given by:
	*
	* PRF(secret, label, seed) = P_<hash>(secret, label + seed)
	*
	* where hash is SHA-256 for all cipher suites defined in RFC 5246 as well as
	* those published prior to TLS v1.2 while the TLS v1.2 protocol is in effect,
	* unless defined otherwise by the cipher suite.
	*
	* P_<hash> is an expansion function that uses a single hash function to expand
	* a secret and seed into an arbitrary quantity of output:
	*
	* P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
	* HMAC_<hash>(secret, A(2) + seed) +
	* HMAC_<hash>(secret, A(3) + seed) + ...
	*
	* where + indicates concatenation. P_<hash> can be iterated as many times as
	* is necessary to produce the required quantity of data.
	*
	* A(i) is defined as:
	* A(0) = seed
	* A(i) = HMAC_<hash>(secret, A(i-1))
	*/
	#include <stdio.h>
	#include <stdarg.h>
	#include <string.h>
	#include <openssl/evp.h>
	#include <openssl/kdf.h>
	#include <openssl/core_names.h>
	#include <openssl/params.h>
	#include <openssl/proverr.h>
	#include "internal/cryptlib.h"
	#include "internal/numbers.h"
	#include "crypto/evp.h"
	#include "prov/provider_ctx.h"
	#include "prov/providercommon.h"
	#include "prov/implementations.h"
	#include "prov/provider_util.h"
	#include "internal/e_os.h"

	static OSSL_FUNC_kdf_newctx_fn kdf_tls1_prf_new;
	static OSSL_FUNC_kdf_dupctx_fn kdf_tls1_prf_dup;
	static OSSL_FUNC_kdf_freectx_fn kdf_tls1_prf_free;
	static OSSL_FUNC_kdf_reset_fn kdf_tls1_prf_reset;
	static OSSL_FUNC_kdf_derive_fn kdf_tls1_prf_derive;
	static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params;
	static OSSL_FUNC_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params;
	static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_tls1_prf_gettable_ctx_params;
	static OSSL_FUNC_kdf_get_ctx_params_fn kdf_tls1_prf_get_ctx_params;

	static int tls1_prf_alg(EVP_MAC_CTX mdctx, EVP_MAC_CTX sha1ctx,
	const unsigned char *sec, size_t slen,
	const unsigned char *seed, size_t seed_len,
	unsigned char *out, size_t olen);

	#define TLS1_PRF_MAXBUF 1024

	/* TLS KDF kdf context structure */
	typedef struct {
	void *provctx;

	/* MAC context for the main digest */
	EVP_MAC_CTX *P_hash;
	/* MAC context for SHA1 for the MD5/SHA-1 combined PRF */
	EVP_MAC_CTX *P_sha1;

	/* Secret value to use for PRF */
	unsigned char *sec;
	size_t seclen;
	/* Buffer of concatenated seed data */
	unsigned char seed[TLS1_PRF_MAXBUF];
	size_t seedlen;
	} TLS1_PRF;

	static void kdf_tls1_prf_new(void provctx)
	{
	TLS1_PRF *ctx;

	if (!ossl_prov_is_running())
	return NULL;

	if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
	ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
	ctx->provctx = provctx;
	return ctx;
	}

	static void kdf_tls1_prf_free(void *vctx)
	{
	TLS1_PRF ctx = (TLS1_PRF )vctx;

	if (ctx != NULL) {
	kdf_tls1_prf_reset(ctx);
	OPENSSL_free(ctx);
	}
	}

	static void kdf_tls1_prf_reset(void *vctx)
	{
	TLS1_PRF ctx = (TLS1_PRF )vctx;
	void *provctx = ctx->provctx;

	EVP_MAC_CTX_free(ctx->P_hash);
	EVP_MAC_CTX_free(ctx->P_sha1);
	OPENSSL_clear_free(ctx->sec, ctx->seclen);
	OPENSSL_cleanse(ctx->seed, ctx->seedlen);
	memset(ctx, 0, sizeof(*ctx));
	ctx->provctx = provctx;
	}

	static void kdf_tls1_prf_dup(void vctx)
	{
	const TLS1_PRF src = (const TLS1_PRF )vctx;
	TLS1_PRF *dest;

	dest = kdf_tls1_prf_new(src->provctx);
	if (dest != NULL) {
	if (src->P_hash != NULL
	&& (dest->P_hash = EVP_MAC_CTX_dup(src->P_hash)) == NULL)
	goto err;
	if (src->P_sha1 != NULL
	&& (dest->P_sha1 = EVP_MAC_CTX_dup(src->P_sha1)) == NULL)
	goto err;
	if (!ossl_prov_memdup(src->sec, src->seclen, &dest->sec, &dest->seclen))
	goto err;
	memcpy(dest->seed, src->seed, src->seedlen);
	dest->seedlen = src->seedlen;
	}
	return dest;

	err:
	kdf_tls1_prf_free(dest);
	return NULL;
	}

	static int kdf_tls1_prf_derive(void vctx, unsigned char key, size_t keylen,
	const OSSL_PARAM params[])
	{
	TLS1_PRF ctx = (TLS1_PRF )vctx;

	if (!ossl_prov_is_running() \|\| !kdf_tls1_prf_set_ctx_params(ctx, params))
	return 0;

	if (ctx->P_hash == NULL) {
	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
	return 0;
	}
	if (ctx->sec == NULL) {
	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
	return 0;
	}
	if (ctx->seedlen == 0) {
	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
	return 0;
	}
	if (keylen == 0) {
	ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
	return 0;
	}

	return tls1_prf_alg(ctx->P_hash, ctx->P_sha1,
	ctx->sec, ctx->seclen,
	ctx->seed, ctx->seedlen,
	key, keylen);
	}

	static int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
	{
	const OSSL_PARAM *p;
	TLS1_PRF *ctx = vctx;
	OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);

	if (params == NULL)
	return 1;

	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
	if (strcasecmp(p->data, SN_md5_sha1) == 0) {
	if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
	OSSL_MAC_NAME_HMAC,
	NULL, SN_md5, libctx)
	\|\| !ossl_prov_macctx_load_from_params(&ctx->P_sha1, params,
	OSSL_MAC_NAME_HMAC,
	NULL, SN_sha1, libctx))
	return 0;
	} else {
	EVP_MAC_CTX_free(ctx->P_sha1);
	if (!ossl_prov_macctx_load_from_params(&ctx->P_hash, params,
	OSSL_MAC_NAME_HMAC,
	NULL, NULL, libctx))
	return 0;
	}
	}

	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
	OPENSSL_clear_free(ctx->sec, ctx->seclen);
	ctx->sec = NULL;
	if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
	return 0;
	}
	/* The seed fields concatenate, so process them all */
	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
	for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
	OSSL_KDF_PARAM_SEED)) {
	const void *q = ctx->seed + ctx->seedlen;
	size_t sz = 0;

	if (p->data_size != 0
	&& p->data != NULL
	&& !OSSL_PARAM_get_octet_string(p, (void **)&q,
	TLS1_PRF_MAXBUF - ctx->seedlen,
	&sz))
	return 0;
	ctx->seedlen += sz;
	}
	}
	return 1;
	}

	static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(
	ossl_unused void ctx, ossl_unused void provctx)
	{
	static const OSSL_PARAM known_settable_ctx_params[] = {
	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
	OSSL_PARAM_END
	};
	return known_settable_ctx_params;
	}

	static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
	{
	OSSL_PARAM *p;

	if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
	return OSSL_PARAM_set_size_t(p, SIZE_MAX);
	return -2;
	}

	static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(
	ossl_unused void ctx, ossl_unused void provctx)
	{
	static const OSSL_PARAM known_gettable_ctx_params[] = {
	OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
	OSSL_PARAM_END
	};
	return known_gettable_ctx_params;
	}

	const OSSL_DISPATCH ossl_kdf_tls1_prf_functions[] = {
	{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
	{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_tls1_prf_dup },
	{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
	{ OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
	{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
	{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
	(void(*)(void))kdf_tls1_prf_settable_ctx_params },
	{ OSSL_FUNC_KDF_SET_CTX_PARAMS,
	(void(*)(void))kdf_tls1_prf_set_ctx_params },
	{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
	(void(*)(void))kdf_tls1_prf_gettable_ctx_params },
	{ OSSL_FUNC_KDF_GET_CTX_PARAMS,
	(void(*)(void))kdf_tls1_prf_get_ctx_params },
	{ 0, NULL }
	};

	/*
	* Refer to "The TLS Protocol Version 1.0" Section 5
	* (https://tools.ietf.org/html/rfc2246#section-5) and
	* "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
	* (https://tools.ietf.org/html/rfc5246#section-5).
	*
	* P_<hash> is an expansion function that uses a single hash function to expand
	* a secret and seed into an arbitrary quantity of output:
	*
	* P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
	* HMAC_<hash>(secret, A(2) + seed) +
	* HMAC_<hash>(secret, A(3) + seed) + ...
	*
	* where + indicates concatenation. P_<hash> can be iterated as many times as
	* is necessary to produce the required quantity of data.
	*
	* A(i) is defined as:
	* A(0) = seed
	* A(i) = HMAC_<hash>(secret, A(i-1))
	*/
	static int tls1_prf_P_hash(EVP_MAC_CTX *ctx_init,
	const unsigned char *sec, size_t sec_len,
	const unsigned char *seed, size_t seed_len,
	unsigned char *out, size_t olen)
	{
	size_t chunk;
	EVP_MAC_CTX ctx = NULL, ctx_Ai = NULL;
	unsigned char Ai[EVP_MAX_MD_SIZE];
	size_t Ai_len;
	int ret = 0;

	if (!EVP_MAC_init(ctx_init, sec, sec_len, NULL))
	goto err;
	chunk = EVP_MAC_CTX_get_mac_size(ctx_init);
	if (chunk == 0)
	goto err;
	/* A(0) = seed */
	ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
	if (ctx_Ai == NULL)
	goto err;
	if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
	goto err;

	for (;;) {
	/* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
	if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
	goto err;
	EVP_MAC_CTX_free(ctx_Ai);
	ctx_Ai = NULL;

	/* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
	ctx = EVP_MAC_CTX_dup(ctx_init);
	if (ctx == NULL)
	goto err;
	if (!EVP_MAC_update(ctx, Ai, Ai_len))
	goto err;
	/* save state for calculating next A(i) value */
	if (olen > chunk) {
	ctx_Ai = EVP_MAC_CTX_dup(ctx);
	if (ctx_Ai == NULL)
	goto err;
	}
	if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
	goto err;
	if (olen <= chunk) {
	/* last chunk - use Ai as temp bounce buffer */
	if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
	goto err;
	memcpy(out, Ai, olen);
	break;
	}
	if (!EVP_MAC_final(ctx, out, NULL, olen))
	goto err;
	EVP_MAC_CTX_free(ctx);
	ctx = NULL;
	out += chunk;
	olen -= chunk;
	}
	ret = 1;
	err:
	EVP_MAC_CTX_free(ctx);
	EVP_MAC_CTX_free(ctx_Ai);
	OPENSSL_cleanse(Ai, sizeof(Ai));
	return ret;
	}

	/*
	* Refer to "The TLS Protocol Version 1.0" Section 5
	* (https://tools.ietf.org/html/rfc2246#section-5) and
	* "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
	* (https://tools.ietf.org/html/rfc5246#section-5).
	*
	* For TLS v1.0 and TLS v1.1:
	*
	* PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
	* P_SHA-1(S2, label + seed)
	*
	* S1 is taken from the first half of the secret, S2 from the second half.
	*
	* L_S = length in bytes of secret;
	* L_S1 = L_S2 = ceil(L_S / 2);
	*
	* For TLS v1.2:
	*
	* PRF(secret, label, seed) = P_<hash>(secret, label + seed)
	*/
	static int tls1_prf_alg(EVP_MAC_CTX mdctx, EVP_MAC_CTX sha1ctx,
	const unsigned char *sec, size_t slen,
	const unsigned char *seed, size_t seed_len,
	unsigned char *out, size_t olen)
	{
	if (sha1ctx != NULL) {
	/* TLS v1.0 and TLS v1.1 */
	size_t i;
	unsigned char *tmp;
	/* calc: L_S1 = L_S2 = ceil(L_S / 2) */
	size_t L_S1 = (slen + 1) / 2;
	size_t L_S2 = L_S1;

	if (!tls1_prf_P_hash(mdctx, sec, L_S1,
	seed, seed_len, out, olen))
	return 0;

	if ((tmp = OPENSSL_malloc(olen)) == NULL) {
	ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
	return 0;
	}

	if (!tls1_prf_P_hash(sha1ctx, sec + slen - L_S2, L_S2,
	seed, seed_len, tmp, olen)) {
	OPENSSL_clear_free(tmp, olen);
	return 0;
	}
	for (i = 0; i < olen; i++)
	out[i] ^= tmp[i];
	OPENSSL_clear_free(tmp, olen);
	return 1;
	}

	/* TLS v1.2 */
	if (!tls1_prf_P_hash(mdctx, sec, slen, seed, seed_len, out, olen))
	return 0;

	return 1;
	}