/*

 * Copyright 2016-2026 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))

 */

/*

 * Low level APIs (such as DH) are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#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 "prov/securitycheck.h"

#include "internal/e_os.h"

#include "internal/safe_math.h"

OSSL_SAFE_MATH_UNSIGNED(size_t, size_t)

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 TLS_MD_MASTER_SECRET_CONST "\x6d\x61\x73\x74\x65\x72\x20\x73\x65\x63\x72\x65\x74"

#define TLS_MD_MASTER_SECRET_CONST_SIZE 13

/* 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;

    /* Concatenated seed data */

    unsigned char *seed;

    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)

        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_clear_free(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;

        if (!ossl_prov_memdup(src->seed, src->seedlen, &dest->seed,

                &dest->seedlen))

            goto err;

    }

    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;

    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);

    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;

    }

    /*

     * The seed buffer is prepended with a label.

     * If EMS mode is enforced then the label "master secret" is not allowed,

     * We do the check this way since the PRF is used for other purposes, as well

     * as "extended master secret".

     */

    if (ossl_tls1_prf_ems_check_enabled(libctx)) {

        if (ctx->seedlen >= TLS_MD_MASTER_SECRET_CONST_SIZE

            && memcmp(ctx->seed, TLS_MD_MASTER_SECRET_CONST,

                   TLS_MD_MASTER_SECRET_CONST_SIZE)

                == 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_EMS_NOT_ENABLED);

            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 (OPENSSL_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);

            ctx->P_sha1 = NULL;

            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)) {

            if (p->data_size != 0 && p->data != NULL) {

                const void *val = NULL;

                size_t sz = 0;

                unsigned char *seed;

                size_t seedlen;

                int err = 0;

                if (!OSSL_PARAM_get_octet_string_ptr(p, &val, &sz))

                    return 0;

                seedlen = safe_add_size_t(ctx->seedlen, sz, &err);

                if (err)

                    return 0;

                seed = OPENSSL_clear_realloc(ctx->seed, ctx->seedlen, seedlen);

                if (!seed)

                    return 0;

                ctx->seed = seed;

                if (ossl_assert(sz != 0))

                    memcpy(ctx->seed + ctx->seedlen, val, sz);

                ctx->seedlen = seedlen;

            }

        }

    }

    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 },

    OSSL_DISPATCH_END

};

/*

 * 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)

            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;

}