/*

 * Copyright 2018-2023 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

 */

/*

 * DES low level APIs are deprecated for public use, but still ok for internal

 * use.  We access the DES_set_odd_parity(3) function here.

 */

#include "internal/deprecated.h"

#include <stdlib.h>

#include <stdarg.h>

#include <string.h>

#include <openssl/core_names.h>

#include <openssl/des.h>

#include <openssl/evp.h>

#include <openssl/kdf.h>

#include <openssl/proverr.h>

#include "internal/cryptlib.h"

#include "crypto/evp.h"

#include "internal/numbers.h"

#include "prov/implementations.h"

#include "prov/provider_ctx.h"

#include "prov/provider_util.h"

#include "prov/providercommon.h"

/* KRB5 KDF defined in RFC 3961, Section 5.1 */

static OSSL_FUNC_kdf_newctx_fn krb5kdf_new;

static OSSL_FUNC_kdf_dupctx_fn krb5kdf_dup;

static OSSL_FUNC_kdf_freectx_fn krb5kdf_free;

static OSSL_FUNC_kdf_reset_fn krb5kdf_reset;

static OSSL_FUNC_kdf_derive_fn krb5kdf_derive;

static OSSL_FUNC_kdf_settable_ctx_params_fn krb5kdf_settable_ctx_params;

static OSSL_FUNC_kdf_set_ctx_params_fn krb5kdf_set_ctx_params;

static OSSL_FUNC_kdf_gettable_ctx_params_fn krb5kdf_gettable_ctx_params;

static OSSL_FUNC_kdf_get_ctx_params_fn krb5kdf_get_ctx_params;

static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,

                   const unsigned char *key, size_t key_len,

                   const unsigned char *constant, size_t constant_len,

                   unsigned char *okey, size_t okey_len);

typedef struct {

    void *provctx;

    PROV_CIPHER cipher;

    unsigned char *key;

    size_t key_len;

    unsigned char *constant;

    size_t constant_len;

} KRB5KDF_CTX;

static void *krb5kdf_new(void *provctx)

{

    KRB5KDF_CTX *ctx;

    if (!ossl_prov_is_running())

        return NULL;

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

        return NULL;

    ctx->provctx = provctx;

    return ctx;

}

static void krb5kdf_free(void *vctx)

{

    KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;

    if (ctx != NULL) {

        krb5kdf_reset(ctx);

        OPENSSL_free(ctx);

    }

}

static void krb5kdf_reset(void *vctx)

{

    KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;

    void *provctx = ctx->provctx;

    ossl_prov_cipher_reset(&ctx->cipher);

    OPENSSL_clear_free(ctx->key, ctx->key_len);

    OPENSSL_clear_free(ctx->constant, ctx->constant_len);

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

    ctx->provctx = provctx;

}

static int krb5kdf_set_membuf(unsigned char **dst, size_t *dst_len,

                              const OSSL_PARAM *p)

{

    OPENSSL_clear_free(*dst, *dst_len);

    *dst = NULL;

    *dst_len = 0;

    return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);

}

static void *krb5kdf_dup(void *vctx)

{

    const KRB5KDF_CTX *src = (const KRB5KDF_CTX *)vctx;

    KRB5KDF_CTX *dest;

    dest = krb5kdf_new(src->provctx);

    if (dest != NULL) {

        if (!ossl_prov_memdup(src->key, src->key_len,

                              &dest->key, &dest->key_len)

                || !ossl_prov_memdup(src->constant, src->constant_len,

                                     &dest->constant , &dest->constant_len)

                || !ossl_prov_cipher_copy(&dest->cipher, &src->cipher))

            goto err;

    }

    return dest;

 err:

    krb5kdf_free(dest);

    return NULL;

}

static int krb5kdf_derive(void *vctx, unsigned char *key, size_t keylen,

                          const OSSL_PARAM params[])

{

    KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;

    const EVP_CIPHER *cipher;

    ENGINE *engine;

    if (!ossl_prov_is_running() || !krb5kdf_set_ctx_params(ctx, params))

        return 0;

    cipher = ossl_prov_cipher_cipher(&ctx->cipher);

    if (cipher == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CIPHER);

        return 0;

    }

    if (ctx->key == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);

        return 0;

    }

    if (ctx->constant == NULL) {

        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_CONSTANT);

        return 0;

    }

    engine = ossl_prov_cipher_engine(&ctx->cipher);

    return KRB5KDF(cipher, engine, ctx->key, ctx->key_len,

                   ctx->constant, ctx->constant_len,

                   key, keylen);

}

static int krb5kdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])

{

    const OSSL_PARAM *p;

    KRB5KDF_CTX *ctx = vctx;

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

    if (params == NULL)

        return 1;

    if (!ossl_prov_cipher_load_from_params(&ctx->cipher, params, provctx))

        return 0;

    if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)

        if (!krb5kdf_set_membuf(&ctx->key, &ctx->key_len, p))

            return 0;

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

        != NULL)

        if (!krb5kdf_set_membuf(&ctx->constant, &ctx->constant_len, p))

            return 0;

    return 1;

}

static const OSSL_PARAM *krb5kdf_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_CIPHER, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),

        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_CONSTANT, NULL, 0),

        OSSL_PARAM_END

    };

    return known_settable_ctx_params;

}

static int krb5kdf_get_ctx_params(void *vctx, OSSL_PARAM params[])

{

    KRB5KDF_CTX *ctx = (KRB5KDF_CTX *)vctx;

    const EVP_CIPHER *cipher;

    size_t len;

    OSSL_PARAM *p;

    cipher = ossl_prov_cipher_cipher(&ctx->cipher);

    if (cipher)

        len = EVP_CIPHER_get_key_length(cipher);

    else

        len = EVP_MAX_KEY_LENGTH;

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

        return OSSL_PARAM_set_size_t(p, len);

    return -2;

}

static const OSSL_PARAM *krb5kdf_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_krb5kdf_functions[] = {

    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))krb5kdf_new },

    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))krb5kdf_dup },

    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))krb5kdf_free },

    { OSSL_FUNC_KDF_RESET, (void(*)(void))krb5kdf_reset },

    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))krb5kdf_derive },

    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,

      (void(*)(void))krb5kdf_settable_ctx_params },

    { OSSL_FUNC_KDF_SET_CTX_PARAMS,

      (void(*)(void))krb5kdf_set_ctx_params },

    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,

      (void(*)(void))krb5kdf_gettable_ctx_params },

    { OSSL_FUNC_KDF_GET_CTX_PARAMS,

      (void(*)(void))krb5kdf_get_ctx_params },

    OSSL_DISPATCH_END

};

#ifndef OPENSSL_NO_DES

/*

 * DES3 is a special case, it requires a random-to-key function and its

 * input truncated to 21 bytes of the 24 produced by the cipher.

 * See RFC3961 6.3.1

 */

static int fixup_des3_key(unsigned char *key)

{

    unsigned char *cblock;

    int i, j;

    for (i = 2; i >= 0; i--) {

        cblock = &key[i * 8];

        memmove(cblock, &key[i * 7], 7);

        cblock[7] = 0;

        for (j = 0; j < 7; j++)

            cblock[7] |= (cblock[j] & 1) << (j + 1);

        DES_set_odd_parity((DES_cblock *)cblock);

    }

    /* fail if keys are such that triple des degrades to single des */

    if (CRYPTO_memcmp(&key[0], &key[8], 8) == 0 ||

        CRYPTO_memcmp(&key[8], &key[16], 8) == 0) {

        return 0;

    }

    return 1;

}

#endif

/*

 * N-fold(K) where blocksize is N, and constant_len is K

 * Note: Here |= denotes concatenation

 *

 * L = lcm(N,K)

 * R = L/K

 *

 * for r: 1 -> R

 *   s |= constant rot 13*(r-1))

 *

 * block = 0

 * for k: 1 -> K

 *   block += s[N(k-1)..(N-1)k] (one's complement addition)

 *

 * Optimizing for space we compute:

 * for each l in L-1 -> 0:

 *   s[l] = (constant rot 13*(l/K))[l%k]

 *   block[l % N] += s[l] (with carry)

 * finally add carry if any

 */

static void n_fold(unsigned char *block, unsigned int blocksize,

                   const unsigned char *constant, size_t constant_len)

{

    unsigned int tmp, gcd, remainder, lcm, carry;

    int b, l;

    if (constant_len == blocksize) {

        memcpy(block, constant, constant_len);

        return;

    }

    /* Least Common Multiple of lengths: LCM(a,b)*/

    gcd = blocksize;

    remainder = constant_len;

    /* Calculate Great Common Divisor first GCD(a,b) */

    while (remainder != 0) {

        tmp = gcd % remainder;

        gcd = remainder;

        remainder = tmp;

    }

    /* resulting a is the GCD, LCM(a,b) = |a*b|/GCD(a,b) */

    lcm = blocksize * constant_len / gcd;

    /* now spread out the bits */

    memset(block, 0, blocksize);

    /* last to first to be able to bring carry forward */

    carry = 0;

    for (l = lcm - 1; l >= 0; l--) {

        unsigned int rotbits, rshift, rbyte;

        /* destination byte in block is l % N */

        b = l % blocksize;

        /* Our virtual s buffer is R = L/K long (K = constant_len) */

        /* So we rotate backwards from R-1 to 0 (none) rotations */

        rotbits = 13 * (l / constant_len);

        /* find the byte on s where rotbits falls onto */

        rbyte = l - (rotbits / 8);

        /* calculate how much shift on that byte */

        rshift = rotbits & 0x07;

        /* rbyte % constant_len gives us the unrotated byte in the

         * constant buffer, get also the previous byte then

         * appropriately shift them to get the rotated byte we need */

        tmp = (constant[(rbyte-1) % constant_len] << (8 - rshift)

               | constant[rbyte % constant_len] >> rshift)

              & 0xff;

        /* add with carry to any value placed by previous passes */

        tmp += carry + block[b];

        block[b] = tmp & 0xff;

        /* save any carry that may be left */

        carry = tmp >> 8;

    }

    /* if any carry is left at the end, add it through the number */

    for (b = blocksize - 1; b >= 0 && carry != 0; b--) {

        carry += block[b];

        block[b] = carry & 0xff;

        carry >>= 8;

    }

}

static int cipher_init(EVP_CIPHER_CTX *ctx,

                       const EVP_CIPHER *cipher, ENGINE *engine,

                       const unsigned char *key, size_t key_len)

{

    int klen, ret;

    ret = EVP_EncryptInit_ex(ctx, cipher, engine, key, NULL);

    if (!ret)

        goto out;

    /* set the key len for the odd variable key len cipher */

    klen = EVP_CIPHER_CTX_get_key_length(ctx);

    if (key_len != (size_t)klen) {

        ret = EVP_CIPHER_CTX_set_key_length(ctx, key_len);

        if (ret <= 0) {

            ret = 0;

            goto out;

        }

    }

    /* we never want padding, either the length requested is a multiple of

     * the cipher block size or we are passed a cipher that can cope with

     * partial blocks via techniques like cipher text stealing */

    ret = EVP_CIPHER_CTX_set_padding(ctx, 0);

    if (!ret)

        goto out;

out:

    return ret;

}

static int KRB5KDF(const EVP_CIPHER *cipher, ENGINE *engine,

                   const unsigned char *key, size_t key_len,

                   const unsigned char *constant, size_t constant_len,

                   unsigned char *okey, size_t okey_len)

{

    EVP_CIPHER_CTX *ctx = NULL;

    unsigned char block[EVP_MAX_BLOCK_LENGTH * 2];

    unsigned char *plainblock, *cipherblock;

    size_t blocksize;

    size_t cipherlen;

    size_t osize;

#ifndef OPENSSL_NO_DES

    int des3_no_fixup = 0;

#endif

    int ret;

    if (key_len != okey_len) {

#ifndef OPENSSL_NO_DES

        /* special case for 3des, where the caller may be requesting

         * the random raw key, instead of the fixed up key  */

        if (EVP_CIPHER_get_nid(cipher) == NID_des_ede3_cbc &&

            key_len == 24 && okey_len == 21) {

                des3_no_fixup = 1;

        } else {

#endif

            ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);

            return 0;

#ifndef OPENSSL_NO_DES

        }

#endif

    }

    ctx = EVP_CIPHER_CTX_new();

    if (ctx == NULL)

        return 0;

    ret = cipher_init(ctx, cipher, engine, key, key_len);

    if (!ret)

        goto out;

    /* Initialize input block */

    blocksize = EVP_CIPHER_CTX_get_block_size(ctx);

    if (constant_len > blocksize) {

        ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CONSTANT_LENGTH);

        ret = 0;

        goto out;

    }

    n_fold(block, blocksize, constant, constant_len);

    plainblock = block;

    cipherblock = block + EVP_MAX_BLOCK_LENGTH;

    for (osize = 0; osize < okey_len; osize += cipherlen) {

        int olen;

        ret = EVP_EncryptUpdate(ctx, cipherblock, &olen,

                                plainblock, blocksize);

        if (!ret)

            goto out;

        cipherlen = olen;

        ret = EVP_EncryptFinal_ex(ctx, cipherblock, &olen);

        if (!ret)

            goto out;

        if (olen != 0) {

            ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_FINAL_BLOCK_LENGTH);

            ret = 0;

            goto out;

        }

        /* write cipherblock out */

        if (cipherlen > okey_len - osize)

            cipherlen = okey_len - osize;

        memcpy(okey + osize, cipherblock, cipherlen);

        if (okey_len > osize + cipherlen) {

            /* we need to reinitialize cipher context per spec */

            ret = EVP_CIPHER_CTX_reset(ctx);

            if (!ret)

                goto out;

            ret = cipher_init(ctx, cipher, engine, key, key_len);

            if (!ret)

                goto out;

            /* also swap block offsets so last ciphertext becomes new

             * plaintext */

            plainblock = cipherblock;

            if (cipherblock == block) {

                cipherblock += EVP_MAX_BLOCK_LENGTH;

            } else {

                cipherblock = block;

            }

        }

    }

#ifndef OPENSSL_NO_DES

    if (EVP_CIPHER_get_nid(cipher) == NID_des_ede3_cbc && !des3_no_fixup) {

        ret = fixup_des3_key(okey);

        if (!ret) {

            ERR_raise(ERR_LIB_PROV, PROV_R_FAILED_TO_GENERATE_KEY);

            goto out;

        }

    }

#endif

    ret = 1;

out:

    EVP_CIPHER_CTX_free(ctx);

    OPENSSL_cleanse(block, EVP_MAX_BLOCK_LENGTH * 2);

    return ret;

}