/*

 * Copyright 2018 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

 */

#include <stdlib.h>

#include <stdarg.h>

#include <string.h>

#include <openssl/hmac.h>

#include <openssl/evp.h>

#include <openssl/kdf.h>

#include "internal/cryptlib.h"

#include "crypto/evp.h"

#include "kdf_local.h"

static void kdf_pbkdf2_reset(EVP_KDF_IMPL *impl);

static void kdf_pbkdf2_init(EVP_KDF_IMPL *impl);

static int pkcs5_pbkdf2_alg(const char *pass, size_t passlen,

                            const unsigned char *salt, int saltlen, int iter,

                            const EVP_MD *digest, unsigned char *key,

                            size_t keylen);

struct evp_kdf_impl_st {

    unsigned char *pass;

    size_t pass_len;

    unsigned char *salt;

    size_t salt_len;

    int iter;

    const EVP_MD *md;

};

static EVP_KDF_IMPL *kdf_pbkdf2_new(void)

{

    EVP_KDF_IMPL *impl;

    impl = OPENSSL_zalloc(sizeof(*impl));

    if (impl == NULL) {

        KDFerr(KDF_F_KDF_PBKDF2_NEW, ERR_R_MALLOC_FAILURE);

        return NULL;

    }

    kdf_pbkdf2_init(impl);

    return impl;

}

static void kdf_pbkdf2_free(EVP_KDF_IMPL *impl)

{

    kdf_pbkdf2_reset(impl);

    OPENSSL_free(impl);

}

static void kdf_pbkdf2_reset(EVP_KDF_IMPL *impl)

{

    OPENSSL_free(impl->salt);

    OPENSSL_clear_free(impl->pass, impl->pass_len);

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

    kdf_pbkdf2_init(impl);

}

static void kdf_pbkdf2_init(EVP_KDF_IMPL *impl)

{

    impl->iter = PKCS5_DEFAULT_ITER;

    impl->md = EVP_sha1();

}

static int pbkdf2_set_membuf(unsigned char **buffer, size_t *buflen,

                             const unsigned char *new_buffer,

                             size_t new_buflen)

{

    if (new_buffer == NULL)

        return 1;

    OPENSSL_clear_free(*buffer, *buflen);

    if (new_buflen > 0) {

        *buffer = OPENSSL_memdup(new_buffer, new_buflen);

    } else {

        *buffer = OPENSSL_malloc(1);

    }

    if (*buffer == NULL) {

        KDFerr(KDF_F_PBKDF2_SET_MEMBUF, ERR_R_MALLOC_FAILURE);

        return 0;

    }

    *buflen = new_buflen;

    return 1;

}

static int kdf_pbkdf2_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)

{

    int iter;

    const unsigned char *p;

    size_t len;

    const EVP_MD *md;

    switch (cmd) {

    case EVP_KDF_CTRL_SET_PASS:

        p = va_arg(args, const unsigned char *);

        len = va_arg(args, size_t);

        return pbkdf2_set_membuf(&impl->pass, &impl->pass_len, p, len);

    case EVP_KDF_CTRL_SET_SALT:

        p = va_arg(args, const unsigned char *);

        len = va_arg(args, size_t);

        return pbkdf2_set_membuf(&impl->salt, &impl->salt_len, p, len);

    case EVP_KDF_CTRL_SET_ITER:

        iter = va_arg(args, int);

        if (iter < 1)

            return 0;

        impl->iter = iter;

        return 1;

    case EVP_KDF_CTRL_SET_MD:

        md = va_arg(args, const EVP_MD *);

        if (md == NULL)

            return 0;

        impl->md = md;

        return 1;

    default:

        return -2;

    }

}

static int kdf_pbkdf2_ctrl_str(EVP_KDF_IMPL *impl, const char *type,

                               const char *value)

{

    if (value == NULL) {

        KDFerr(KDF_F_KDF_PBKDF2_CTRL_STR, KDF_R_VALUE_MISSING);

        return 0;

    }

    if (strcmp(type, "pass") == 0)

        return kdf_str2ctrl(impl, kdf_pbkdf2_ctrl, EVP_KDF_CTRL_SET_PASS,

                            value);

    if (strcmp(type, "hexpass") == 0)

        return kdf_hex2ctrl(impl, kdf_pbkdf2_ctrl, EVP_KDF_CTRL_SET_PASS,

                            value);

    if (strcmp(type, "salt") == 0)

        return kdf_str2ctrl(impl, kdf_pbkdf2_ctrl, EVP_KDF_CTRL_SET_SALT,

                            value);

    if (strcmp(type, "hexsalt") == 0)

        return kdf_hex2ctrl(impl, kdf_pbkdf2_ctrl, EVP_KDF_CTRL_SET_SALT,

                            value);

    if (strcmp(type, "iter") == 0)

        return call_ctrl(kdf_pbkdf2_ctrl, impl, EVP_KDF_CTRL_SET_ITER,

                         atoi(value));

    if (strcmp(type, "digest") == 0)

        return kdf_md2ctrl(impl, kdf_pbkdf2_ctrl, EVP_KDF_CTRL_SET_MD, value);

    return -2;

}

static int kdf_pbkdf2_derive(EVP_KDF_IMPL *impl, unsigned char *key,

                             size_t keylen)

{

    if (impl->pass == NULL) {

        KDFerr(KDF_F_KDF_PBKDF2_DERIVE, KDF_R_MISSING_PASS);

        return 0;

    }

    if (impl->salt == NULL) {

        KDFerr(KDF_F_KDF_PBKDF2_DERIVE, KDF_R_MISSING_SALT);

        return 0;

    }

    return pkcs5_pbkdf2_alg((char *)impl->pass, impl->pass_len,

                            impl->salt, impl->salt_len, impl->iter,

                            impl->md, key, keylen);

}

const EVP_KDF_METHOD pbkdf2_kdf_meth = {

    EVP_KDF_PBKDF2,

    kdf_pbkdf2_new,

    kdf_pbkdf2_free,

    kdf_pbkdf2_reset,

    kdf_pbkdf2_ctrl,

    kdf_pbkdf2_ctrl_str,

    NULL,

    kdf_pbkdf2_derive

};

/*

 * This is an implementation of PKCS#5 v2.0 password based encryption key

 * derivation function PBKDF2. SHA1 version verified against test vectors

 * posted by Peter Gutmann to the PKCS-TNG mailing list.

 */

static int pkcs5_pbkdf2_alg(const char *pass, size_t passlen,

                            const unsigned char *salt, int saltlen, int iter,

                            const EVP_MD *digest, unsigned char *key,

                            size_t keylen)

{

    int ret = 0;

    unsigned char digtmp[EVP_MAX_MD_SIZE], *p, itmp[4];

    int cplen, j, k, tkeylen, mdlen;

    unsigned long i = 1;

    HMAC_CTX *hctx_tpl = NULL, *hctx = NULL;

    mdlen = EVP_MD_size(digest);

    if (mdlen < 0)

        return 0;

    hctx_tpl = HMAC_CTX_new();

    if (hctx_tpl == NULL)

        return 0;

    p = key;

    tkeylen = keylen;

    if (!HMAC_Init_ex(hctx_tpl, pass, passlen, digest, NULL))

        goto err;

    hctx = HMAC_CTX_new();

    if (hctx == NULL)

        goto err;

    while (tkeylen) {

        if (tkeylen > mdlen)

            cplen = mdlen;

        else

            cplen = tkeylen;

        /*

         * We are unlikely to ever use more than 256 blocks (5120 bits!) but

         * just in case...

         */

        itmp[0] = (unsigned char)((i >> 24) & 0xff);

        itmp[1] = (unsigned char)((i >> 16) & 0xff);

        itmp[2] = (unsigned char)((i >> 8) & 0xff);

        itmp[3] = (unsigned char)(i & 0xff);

        if (!HMAC_CTX_copy(hctx, hctx_tpl))

            goto err;

        if (!HMAC_Update(hctx, salt, saltlen)

                || !HMAC_Update(hctx, itmp, 4)

                || !HMAC_Final(hctx, digtmp, NULL))

            goto err;

        memcpy(p, digtmp, cplen);

        for (j = 1; j < iter; j++) {

            if (!HMAC_CTX_copy(hctx, hctx_tpl))

                goto err;

            if (!HMAC_Update(hctx, digtmp, mdlen)

                    || !HMAC_Final(hctx, digtmp, NULL))

                goto err;

            for (k = 0; k < cplen; k++)

                p[k] ^= digtmp[k];

        }

        tkeylen -= cplen;

        i++;

        p += cplen;

    }

    ret = 1;

err:

    HMAC_CTX_free(hctx);

    HMAC_CTX_free(hctx_tpl);

    return ret;

}