/*

 * Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright (c) 2019, Oracle and/or its affiliates.  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 https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final

 * Section 4.1.

 *

 * The Single Step KDF algorithm is given by:

 *

 * Result(0) = empty bit string (i.e., the null string).

 * For i = 1 to reps, do the following:

 *   Increment counter by 1.

 *   Result(i) = Result(i - 1) || H(counter || Z || FixedInfo).

 * DKM = LeftmostBits(Result(reps), L))

 *

 * NOTES:

 *   Z is a shared secret required to produce the derived key material.

 *   counter is a 4 byte buffer.

 *   FixedInfo is a bit string containing context specific data.

 *   DKM is the output derived key material.

 *   L is the required size of the DKM.

 *   reps = [L / H_outputBits]

 *   H(x) is the auxiliary function that can be either a hash, HMAC or KMAC.

 *   H_outputBits is the length of the output of the auxiliary function H(x).

 *

 * Currently there is not a comprehensive list of test vectors for this

 * algorithm, especially for H(x) = HMAC and H(x) = KMAC.

 * Test vectors for H(x) = Hash are indirectly used by CAVS KAS tests.

 */

#include <stdlib.h>

#include <stdarg.h>

#include <string.h>

#include <openssl/hmac.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/params.h"

typedef struct {

    void *provctx;

    EVP_MAC_CTX *macctx;         /* H(x) = HMAC_hash OR H(x) = KMAC */

    PROV_DIGEST digest;          /* H(x) = hash(x) */

    unsigned char *secret;

    size_t secret_len;

    unsigned char *info;

    size_t info_len;

    unsigned char *salt;

    size_t salt_len;

    size_t out_len; /* optional KMAC parameter */

    int is_kmac;

} KDF_SSKDF;

#define SSKDF_MAX_INLEN (1<<30)

#define SSKDF_KMAC128_DEFAULT_SALT_SIZE (168 - 4)

#define SSKDF_KMAC256_DEFAULT_SALT_SIZE (136 - 4)

/* KMAC uses a Customisation string of 'KDF' */

static const unsigned char kmac_custom_str[] = { 0x4B, 0x44, 0x46 };

static OSSL_FUNC_kdf_newctx_fn sskdf_new;

static OSSL_FUNC_kdf_dupctx_fn sskdf_dup;

static OSSL_FUNC_kdf_freectx_fn sskdf_free;

static OSSL_FUNC_kdf_reset_fn sskdf_reset;

static OSSL_FUNC_kdf_derive_fn sskdf_derive;

static OSSL_FUNC_kdf_derive_fn x963kdf_derive;

static OSSL_FUNC_kdf_settable_ctx_params_fn sskdf_settable_ctx_params;

static OSSL_FUNC_kdf_set_ctx_params_fn sskdf_set_ctx_params;

static OSSL_FUNC_kdf_gettable_ctx_params_fn sskdf_gettable_ctx_params;

static OSSL_FUNC_kdf_get_ctx_params_fn sskdf_get_ctx_params;

/*

 * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final

 * Section 4. One-Step Key Derivation using H(x) = hash(x)

 * Note: X9.63 also uses this code with the only difference being that the

 * counter is appended to the secret 'z'.

 * i.e.

 *   result[i] = Hash(counter || z || info) for One Step OR

 *   result[i] = Hash(z || counter || info) for X9.63.

 */

static int SSKDF_hash_kdm(const EVP_MD *kdf_md,

                          const unsigned char *z, size_t z_len,

                          const unsigned char *info, size_t info_len,

                          unsigned int append_ctr,

                          unsigned char *derived_key, size_t derived_key_len)

{

    int ret = 0, hlen;

    size_t counter, out_len, len = derived_key_len;

    unsigned char c[4];

    unsigned char mac[EVP_MAX_MD_SIZE];

    unsigned char *out = derived_key;

    EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;

    if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN

            || derived_key_len > SSKDF_MAX_INLEN

            || derived_key_len == 0)

        return 0;

    hlen = EVP_MD_get_size(kdf_md);

    if (hlen <= 0)

        return 0;

    out_len = (size_t)hlen;

    ctx = EVP_MD_CTX_create();

    ctx_init = EVP_MD_CTX_create();

    if (ctx == NULL || ctx_init == NULL)

        goto end;

    if (!EVP_DigestInit(ctx_init, kdf_md))

        goto end;

    for (counter = 1;; counter++) {

        c[0] = (unsigned char)((counter >> 24) & 0xff);

        c[1] = (unsigned char)((counter >> 16) & 0xff);

        c[2] = (unsigned char)((counter >> 8) & 0xff);

        c[3] = (unsigned char)(counter & 0xff);

        if (!(EVP_MD_CTX_copy_ex(ctx, ctx_init)

                && (append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))

                && EVP_DigestUpdate(ctx, z, z_len)

                && (!append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))

                && EVP_DigestUpdate(ctx, info, info_len)))

            goto end;

        if (len >= out_len) {

            if (!EVP_DigestFinal_ex(ctx, out, NULL))

                goto end;

            out += out_len;

            len -= out_len;

            if (len == 0)

                break;

        } else {

            if (!EVP_DigestFinal_ex(ctx, mac, NULL))

                goto end;

            memcpy(out, mac, len);

            break;

        }

    }

    ret = 1;

end:

    EVP_MD_CTX_destroy(ctx);

    EVP_MD_CTX_destroy(ctx_init);

    OPENSSL_cleanse(mac, sizeof(mac));

    return ret;

}

static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom,

                     size_t custom_len, size_t kmac_out_len,

                     size_t derived_key_len, unsigned char **out)

{

    OSSL_PARAM params[2];

    /* Only KMAC has custom data - so return if not KMAC */

    if (custom == NULL)

        return 1;

    params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,

                                                  (void *)custom, custom_len);

    params[1] = OSSL_PARAM_construct_end();

    if (!EVP_MAC_CTX_set_params(ctx, params))

        return 0;

    /* By default only do one iteration if kmac_out_len is not specified */

    if (kmac_out_len == 0)

        kmac_out_len = derived_key_len;

    /* otherwise check the size is valid */

    else if (!(kmac_out_len == derived_key_len

            || kmac_out_len == 20

            || kmac_out_len == 28

            || kmac_out_len == 32

            || kmac_out_len == 48

            || kmac_out_len == 64))

        return 0;

    params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE,

                                            &kmac_out_len);

    if (EVP_MAC_CTX_set_params(ctx, params) <= 0)

        return 0;

    /*

     * For kmac the output buffer can be larger than EVP_MAX_MD_SIZE: so

     * alloc a buffer for this case.

     */

    if (kmac_out_len > EVP_MAX_MD_SIZE) {

        *out = OPENSSL_zalloc(kmac_out_len);

        if (*out == NULL)

            return 0;

    }

    return 1;

}

/*

 * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final

 * Section 4. One-Step Key Derivation using MAC: i.e either

 *     H(x) = HMAC-hash(salt, x) OR

 *     H(x) = KMAC#(salt, x, outbits, CustomString='KDF')

 */

static int SSKDF_mac_kdm(EVP_MAC_CTX *ctx_init,

                         const unsigned char *kmac_custom,

                         size_t kmac_custom_len, size_t kmac_out_len,

                         const unsigned char *salt, size_t salt_len,

                         const unsigned char *z, size_t z_len,

                         const unsigned char *info, size_t info_len,

                         unsigned char *derived_key, size_t derived_key_len)

{

    int ret = 0;

    size_t counter, out_len, len;

    unsigned char c[4];

    unsigned char mac_buf[EVP_MAX_MD_SIZE];

    unsigned char *out = derived_key;

    EVP_MAC_CTX *ctx = NULL;

    unsigned char *mac = mac_buf, *kmac_buffer = NULL;

    if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN

            || derived_key_len > SSKDF_MAX_INLEN

            || derived_key_len == 0)

        return 0;

    if (!kmac_init(ctx_init, kmac_custom, kmac_custom_len, kmac_out_len,

                   derived_key_len, &kmac_buffer))

        goto end;

    if (kmac_buffer != NULL)

        mac = kmac_buffer;

    if (!EVP_MAC_init(ctx_init, salt, salt_len, NULL))

        goto end;

    out_len = EVP_MAC_CTX_get_mac_size(ctx_init); /* output size */

    if (out_len <= 0 || (mac == mac_buf && out_len > sizeof(mac_buf)))

        goto end;

    len = derived_key_len;

    for (counter = 1;; counter++) {

        c[0] = (unsigned char)((counter >> 24) & 0xff);

        c[1] = (unsigned char)((counter >> 16) & 0xff);

        c[2] = (unsigned char)((counter >> 8) & 0xff);

        c[3] = (unsigned char)(counter & 0xff);

        ctx = EVP_MAC_CTX_dup(ctx_init);

        if (!(ctx != NULL

                && EVP_MAC_update(ctx, c, sizeof(c))

                && EVP_MAC_update(ctx, z, z_len)

                && EVP_MAC_update(ctx, info, info_len)))

            goto end;

        if (len >= out_len) {

            if (!EVP_MAC_final(ctx, out, NULL, len))

                goto end;

            out += out_len;

            len -= out_len;

            if (len == 0)

                break;

        } else {

            if (!EVP_MAC_final(ctx, mac, NULL, out_len))

                goto end;

            memcpy(out, mac, len);

            break;

        }

        EVP_MAC_CTX_free(ctx);

        ctx = NULL;

    }

    ret = 1;

end:

    if (kmac_buffer != NULL)

        OPENSSL_clear_free(kmac_buffer, kmac_out_len);

    else

        OPENSSL_cleanse(mac_buf, sizeof(mac_buf));

    EVP_MAC_CTX_free(ctx);

    return ret;

}

static void *sskdf_new(void *provctx)

{

    KDF_SSKDF *ctx;

    if (!ossl_prov_is_running())

        return NULL;

    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)

        ctx->provctx = provctx;

    return ctx;

}

static void sskdf_reset(void *vctx)

{

    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;

    void *provctx = ctx->provctx;

    EVP_MAC_CTX_free(ctx->macctx);

    ossl_prov_digest_reset(&ctx->digest);

    OPENSSL_clear_free(ctx->secret, ctx->secret_len);

    OPENSSL_clear_free(ctx->info, ctx->info_len);

    OPENSSL_clear_free(ctx->salt, ctx->salt_len);

    memset(ctx, 0, sizeof(*ctx));

    ctx->provctx = provctx;

}

static void sskdf_free(void *vctx)

{

    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;

    if (ctx != NULL) {

        sskdf_reset(ctx);

        OPENSSL_free(ctx);

    }

}

static void *sskdf_dup(void *vctx)

{

    const KDF_SSKDF *src = (const KDF_SSKDF *)vctx;

    KDF_SSKDF *dest;

    dest = sskdf_new(src->provctx);

    if (dest != NULL) {

        if (src->macctx != NULL) {

            dest->macctx = EVP_MAC_CTX_dup(src->macctx);

            if (dest->macctx == NULL)

                goto err;

        }

        if (!ossl_prov_memdup(src->info, src->info_len,

                              &dest->info, &dest->info_len)

                || !ossl_prov_memdup(src->salt, src->salt_len,

                                     &dest->salt , &dest->salt_len)

                || !ossl_prov_memdup(src->secret, src->secret_len,

                                     &dest->secret, &dest->secret_len)

                || !ossl_prov_digest_copy(&dest->digest, &src->digest))

            goto err;

        dest->out_len = src->out_len;

        dest->is_kmac = src->is_kmac;

    }

    return dest;

 err:

    sskdf_free(dest);

    return NULL;

}

static size_t sskdf_size(KDF_SSKDF *ctx)

{

    int len;

    const EVP_MD *md = NULL;

    if (ctx->is_kmac)

        return SIZE_MAX;

    md = ossl_prov_digest_md(&ctx->digest);

    if (md == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);

        return 0;

    }

    len = EVP_MD_get_size(md);

    return (len <= 0) ? 0 : (size_t)len;

}

static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen,

                        const OSSL_PARAM params[])

{

    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;

    const EVP_MD *md;

    if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))

        return 0;

    if (ctx->secret == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);

        return 0;

    }

    md = ossl_prov_digest_md(&ctx->digest);

    if (ctx->macctx != NULL) {

        /* H(x) = KMAC or H(x) = HMAC */

        int ret;

        const unsigned char *custom = NULL;

        size_t custom_len = 0;

        int default_salt_len;

        EVP_MAC *mac = EVP_MAC_CTX_get0_mac(ctx->macctx);

        if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_HMAC)) {

            /* H(x) = HMAC(x, salt, hash) */

            if (md == NULL) {

                ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);

                return 0;

            }

            default_salt_len = EVP_MD_get_size(md);

            if (default_salt_len <= 0)

                return 0;

        } else if (ctx->is_kmac) {

            /* H(x) = KMACzzz(x, salt, custom) */

            custom = kmac_custom_str;

            custom_len = sizeof(kmac_custom_str);

            if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128))

                default_salt_len = SSKDF_KMAC128_DEFAULT_SALT_SIZE;

            else

                default_salt_len = SSKDF_KMAC256_DEFAULT_SALT_SIZE;

        } else {

            ERR_raise(ERR_LIB_PROV, PROV_R_UNSUPPORTED_MAC_TYPE);

            return 0;

        }

        /* If no salt is set then use a default_salt of zeros */

        if (ctx->salt == NULL || ctx->salt_len <= 0) {

            ctx->salt = OPENSSL_zalloc(default_salt_len);

            if (ctx->salt == NULL)

                return 0;

            ctx->salt_len = default_salt_len;

        }

        ret = SSKDF_mac_kdm(ctx->macctx,

                            custom, custom_len, ctx->out_len,

                            ctx->salt, ctx->salt_len,

                            ctx->secret, ctx->secret_len,

                            ctx->info, ctx->info_len, key, keylen);

        return ret;

    } else {

        /* H(x) = hash */

        if (md == NULL) {

            ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);

            return 0;

        }

        return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,

                              ctx->info, ctx->info_len, 0, key, keylen);

    }

}

static int x963kdf_derive(void *vctx, unsigned char *key, size_t keylen,

                          const OSSL_PARAM params[])

{

    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;

    const EVP_MD *md;

    if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))

        return 0;

    if (ctx->secret == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);

        return 0;

    }

    if (ctx->macctx != NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED);

        return 0;

    }

    /* H(x) = hash */

    md = ossl_prov_digest_md(&ctx->digest);

    if (md == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);

        return 0;

    }

    return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,

                          ctx->info, ctx->info_len, 1, key, keylen);

}

static int sskdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])

{

    const OSSL_PARAM *p;

    KDF_SSKDF *ctx = vctx;

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

    size_t sz;

    int r;

    if (params == NULL)

        return 1;

    if (!ossl_prov_macctx_load_from_params(&ctx->macctx, params,

                                           NULL, NULL, NULL, libctx))

        return 0;

    if (ctx->macctx != NULL) {

         if (EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),

                          OSSL_MAC_NAME_KMAC128)

             || EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),

                             OSSL_MAC_NAME_KMAC256)) {

             ctx->is_kmac = 1;

         }

    }

    if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))

        return 0;

    r = ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SECRET,

                                     &ctx->secret, &ctx->secret_len);

    if (r == -1)

        r = ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_KEY,

                                         &ctx->secret, &ctx->secret_len);

    if (r == 0)

        return 0;

    if (ossl_param_get1_concat_octet_string(params, OSSL_KDF_PARAM_INFO,

                                            &ctx->info, &ctx->info_len, 0) == 0)

        return 0;

    if (ossl_param_get1_octet_string(params, OSSL_KDF_PARAM_SALT,

                                     &ctx->salt, &ctx->salt_len) == 0)

            return 0;

    if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC_SIZE))

        != NULL) {

        if (!OSSL_PARAM_get_size_t(p, &sz) || sz == 0)

            return 0;

        ctx->out_len = sz;

    }

    return 1;

}

static const OSSL_PARAM *sskdf_settable_ctx_params(ossl_unused void *ctx,

                                                   ossl_unused void *provctx)

{

    static const OSSL_PARAM known_settable_ctx_params[] = {

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),

        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),

        OSSL_PARAM_size_t(OSSL_KDF_PARAM_MAC_SIZE, NULL),

        OSSL_PARAM_END

    };

    return known_settable_ctx_params;

}

static int sskdf_get_ctx_params(void *vctx, OSSL_PARAM params[])

{

    KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;

    OSSL_PARAM *p;

    if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)

        return OSSL_PARAM_set_size_t(p, sskdf_size(ctx));

    return -2;

}

static const OSSL_PARAM *sskdf_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_sskdf_functions[] = {

    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },

    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },

    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },

    { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },

    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))sskdf_derive },

    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,

      (void(*)(void))sskdf_settable_ctx_params },

    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },

    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,

      (void(*)(void))sskdf_gettable_ctx_params },

    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },

    OSSL_DISPATCH_END

};

const OSSL_DISPATCH ossl_kdf_x963_kdf_functions[] = {

    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },

    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },

    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },

    { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },

    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))x963kdf_derive },

    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,

      (void(*)(void))sskdf_settable_ctx_params },

    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },

    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,

      (void(*)(void))sskdf_gettable_ctx_params },

    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },

    OSSL_DISPATCH_END

};