/**
 * \file cipher.c
 *
 * \brief Generic cipher wrapper for mbed TLS
 *
 * \author Adriaan de Jong <dejong@fox-it.com>
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/mbedtls_config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#if defined(MBEDTLS_CIPHER_C)

#include "mbedtls/cipher.h"
#include "mbedtls/cipher_internal.h"

#include <stdlib.h>
#include <string.h>

#if defined(MBEDTLS_GCM_C)
#include "mbedtls/gcm.h"
#endif

#if defined(MBEDTLS_CCM_C)
#include "mbedtls/ccm.h"
#endif

#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
#define MBEDTLS_CIPHER_MODE_STREAM
#endif

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize(void *v, size_t n)
{
    volatile unsigned char *p = (unsigned char *)v;
    while (n--) {
        *p++ = 0;
    }
}

static int supported_init = 0;

const int *mbedtls_cipher_list(void)
{
    const mbedtls_cipher_definition_t *def;
    int *type;

    if (! supported_init) {
        def = mbedtls_cipher_definitions;
        type = mbedtls_cipher_supported;

        while (def->type != 0) {
            *type++ = (*def++).type;
        }

        *type = 0;

        supported_init = 1;
    }

    return (mbedtls_cipher_supported);
}

const mbedtls_cipher_info_t *mbedtls_cipher_info_from_type(const mbedtls_cipher_type_t cipher_type)
{
    const mbedtls_cipher_definition_t *def;

    for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
        if (def->type == cipher_type) {
            return (def->info);
        }

    return (NULL);
}

const mbedtls_cipher_info_t *mbedtls_cipher_info_from_string(const char *cipher_name)
{
    const mbedtls_cipher_definition_t *def;

    if (NULL == cipher_name) {
        return (NULL);
    }

    for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
        if (!  strcmp(def->info->name, cipher_name)) {
            return (def->info);
        }

    return (NULL);
}

const mbedtls_cipher_info_t *mbedtls_cipher_info_from_values(const mbedtls_cipher_id_t cipher_id,
        int key_bitlen,
        const mbedtls_cipher_mode_t mode)
{
    const mbedtls_cipher_definition_t *def;

    for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
        if (def->info->base->cipher == cipher_id &&
            def->info->key_bitlen == (unsigned) key_bitlen &&
            def->info->mode == mode) {
            return (def->info);
        }

    return (NULL);
}

void mbedtls_cipher_init(mbedtls_cipher_context_t *ctx)
{
    memset(ctx, 0, sizeof(mbedtls_cipher_context_t));
}

void mbedtls_cipher_free(mbedtls_cipher_context_t *ctx)
{
    if (ctx == NULL) {
        return;
    }

    if (ctx->cipher_ctx) {
        ctx->cipher_info->base->ctx_free_func(ctx->cipher_ctx);
    }

    mbedtls_zeroize(ctx, sizeof(mbedtls_cipher_context_t));
}

int mbedtls_cipher_setup(mbedtls_cipher_context_t *ctx, const mbedtls_cipher_info_t *cipher_info)
{
    if (NULL == cipher_info || NULL == ctx) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

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

    if (NULL == (ctx->cipher_ctx = cipher_info->base->ctx_alloc_func())) {
        return (MBEDTLS_ERR_CIPHER_ALLOC_FAILED);
    }

    ctx->cipher_info = cipher_info;

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    /*
     * Ignore possible errors caused by a cipher mode that doesn't use padding
     */
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
    (void) mbedtls_cipher_set_padding_mode(ctx, MBEDTLS_PADDING_PKCS7);
#else
    (void) mbedtls_cipher_set_padding_mode(ctx, MBEDTLS_PADDING_NONE);
#endif
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

    return (0);
}

int mbedtls_cipher_setkey(mbedtls_cipher_context_t *ctx, const unsigned char *key,
                          int key_bitlen, const mbedtls_operation_t operation)
{
    if (NULL == ctx || NULL == ctx->cipher_info) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    if ((ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_KEY_LEN) == 0 &&
        (int) ctx->cipher_info->key_bitlen != key_bitlen) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    ctx->key_bitlen = key_bitlen;
    ctx->operation = operation;

    /*
     * For CFB and CTR mode always use the encryption key schedule
     */
    if (MBEDTLS_ENCRYPT == operation ||
        MBEDTLS_MODE_CFB == ctx->cipher_info->mode ||
        MBEDTLS_MODE_CTR == ctx->cipher_info->mode) {
        return ctx->cipher_info->base->setkey_enc_func(ctx->cipher_ctx, key,
                ctx->key_bitlen);
    }

    if (MBEDTLS_DECRYPT == operation)
        return ctx->cipher_info->base->setkey_dec_func(ctx->cipher_ctx, key,
                ctx->key_bitlen);

    return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
}

int mbedtls_cipher_set_iv(mbedtls_cipher_context_t *ctx,
                          const unsigned char *iv, size_t iv_len)
{
    size_t actual_iv_size;

    if (NULL == ctx || NULL == ctx->cipher_info || NULL == iv) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    /* avoid buffer overflow in ctx->iv */
    if (iv_len > MBEDTLS_MAX_IV_LENGTH) {
        return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
    }

    if ((ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_IV_LEN) != 0) {
        actual_iv_size = iv_len;
    } else {
        actual_iv_size = ctx->cipher_info->iv_size;

        /* avoid reading past the end of input buffer */
        if (actual_iv_size > iv_len) {
            return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
        }
    }

    memcpy(ctx->iv, iv, actual_iv_size);
    ctx->iv_size = actual_iv_size;

    return (0);
}

int mbedtls_cipher_reset(mbedtls_cipher_context_t *ctx)
{
    if (NULL == ctx || NULL == ctx->cipher_info) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    ctx->unprocessed_len = 0;

    return (0);
}

#if defined(MBEDTLS_GCM_C)
int mbedtls_cipher_update_ad(mbedtls_cipher_context_t *ctx,
                             const unsigned char *ad, size_t ad_len)
{
    if (NULL == ctx || NULL == ctx->cipher_info) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
        return mbedtls_gcm_starts((mbedtls_gcm_context *) ctx->cipher_ctx, ctx->operation,
                                  ctx->iv, ctx->iv_size, ad, ad_len);
    }

    return (0);
}
#endif /* MBEDTLS_GCM_C */

int mbedtls_cipher_update(mbedtls_cipher_context_t *ctx, const unsigned char *input,
                          size_t ilen, unsigned char *output, size_t *olen)
{
    int ret;
    size_t block_size = 0;

    if (NULL == ctx || NULL == ctx->cipher_info || NULL == olen) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    *olen = 0;
    block_size = mbedtls_cipher_get_block_size(ctx);

    if (ctx->cipher_info->mode == MBEDTLS_MODE_ECB) {
        if (ilen != block_size) {
            return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
        }

        *olen = ilen;

        if (0 != (ret = ctx->cipher_info->base->ecb_func(ctx->cipher_ctx,
                        ctx->operation, input, output))) {
            return (ret);
        }

        return (0);
    }

#if defined(MBEDTLS_GCM_C)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM) {
        *olen = ilen;
        return mbedtls_gcm_update((mbedtls_gcm_context *) ctx->cipher_ctx, ilen, input,
                                  output);
    }
#endif

    if (0 == block_size) {
        return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
    }

    if (input == output &&
        (ctx->unprocessed_len != 0 || ilen % block_size)) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

#if defined(MBEDTLS_CIPHER_MODE_CBC)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CBC) {
        size_t copy_len = 0;

        /*
         * If there is not enough data for a full block, cache it.
         */
        if ((ctx->operation == MBEDTLS_DECRYPT &&
             ilen + ctx->unprocessed_len <= block_size) ||
            (ctx->operation == MBEDTLS_ENCRYPT &&
             ilen + ctx->unprocessed_len < block_size)) {
            memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]), input,
                   ilen);

            ctx->unprocessed_len += ilen;
            return (0);
        }

        /*
         * Process cached data first
         */
        if (0 != ctx->unprocessed_len) {
            copy_len = block_size - ctx->unprocessed_len;

            memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]), input,
                   copy_len);

            if (0 != (ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx,
                            ctx->operation, block_size, ctx->iv,
                            ctx->unprocessed_data, output))) {
                return (ret);
            }

            *olen += block_size;
            output += block_size;
            ctx->unprocessed_len = 0;

            input += copy_len;
            ilen -= copy_len;
        }

        /*
         * Cache final, incomplete block
         */
        if (0 != ilen) {
            if (0 == block_size) {
                return MBEDTLS_ERR_CIPHER_INVALID_CONTEXT;
            }

            copy_len = ilen % block_size;
            if (copy_len == 0 && ctx->operation == MBEDTLS_DECRYPT) {
                copy_len = block_size;
            }

            memcpy(ctx->unprocessed_data, &(input[ilen - copy_len]),
                   copy_len);

            ctx->unprocessed_len += copy_len;
            ilen -= copy_len;
        }

        /*
         * Process remaining full blocks
         */
        if (ilen) {
            if (0 != (ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx,
                            ctx->operation, ilen, ctx->iv, input, output))) {
                return (ret);
            }

            *olen += ilen;
        }

        return (0);
    }
#endif /* MBEDTLS_CIPHER_MODE_CBC */

#if defined(MBEDTLS_CIPHER_MODE_CFB)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CFB) {
        if (0 != (ret = ctx->cipher_info->base->cfb_func(ctx->cipher_ctx,
                        ctx->operation, ilen, &ctx->unprocessed_len, ctx->iv,
                        input, output))) {
            return (ret);
        }

        *olen = ilen;

        return (0);
    }
#endif /* MBEDTLS_CIPHER_MODE_CFB */

#if defined(MBEDTLS_CIPHER_MODE_CTR)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CTR) {
        if (0 != (ret = ctx->cipher_info->base->ctr_func(ctx->cipher_ctx,
                        ilen, &ctx->unprocessed_len, ctx->iv,
                        ctx->unprocessed_data, input, output))) {
            return (ret);
        }

        *olen = ilen;

        return (0);
    }
#endif /* MBEDTLS_CIPHER_MODE_CTR */

#if defined(MBEDTLS_CIPHER_MODE_STREAM)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_STREAM) {
        if (0 != (ret = ctx->cipher_info->base->stream_func(ctx->cipher_ctx,
                        ilen, input, output))) {
            return (ret);
        }

        *olen = ilen;

        return (0);
    }
#endif /* MBEDTLS_CIPHER_MODE_STREAM */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
/*
 * PKCS7 (and PKCS5) padding: fill with ll bytes, with ll = padding_len
 */
static void add_pkcs_padding(unsigned char *output, size_t output_len,
                             size_t data_len)
{
    size_t padding_len = output_len - data_len;
    unsigned char i;

    for (i = 0; i < padding_len; i++) {
        output[data_len + i] = (unsigned char) padding_len;
    }
}

static int get_pkcs_padding(unsigned char *input, size_t input_len,
                            size_t *data_len)
{
    size_t i, pad_idx;
    unsigned char padding_len, bad = 0;

    if (NULL == input || NULL == data_len) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    padding_len = input[input_len - 1];
    *data_len = input_len - padding_len;

    /* Avoid logical || since it results in a branch */
    bad |= padding_len > input_len;
    bad |= padding_len == 0;

    /* The number of bytes checked must be independent of padding_len,
     * so pick input_len, which is usually 8 or 16 (one block) */
    pad_idx = input_len - padding_len;
    for (i = 0; i < input_len; i++) {
        bad |= (input[i] ^ padding_len) * (i >= pad_idx);
    }

    return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));
}
#endif /* MBEDTLS_CIPHER_PADDING_PKCS7 */

#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)
/*
 * One and zeros padding: fill with 80 00 ... 00
 */
static void add_one_and_zeros_padding(unsigned char *output,
                                      size_t output_len, size_t data_len)
{
    size_t padding_len = output_len - data_len;
    unsigned char i = 0;

    output[data_len] = 0x80;
    for (i = 1; i < padding_len; i++) {
        output[data_len + i] = 0x00;
    }
}

static int get_one_and_zeros_padding(unsigned char *input, size_t input_len,
                                     size_t *data_len)
{
    size_t i;
    unsigned char done = 0, prev_done, bad;

    if (NULL == input || NULL == data_len) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    bad = 0xFF;
    *data_len = 0;
    for (i = input_len; i > 0; i--) {
        prev_done = done;
        done |= (input[i - 1] != 0);
        *data_len |= (i - 1) * (done != prev_done);
        bad &= (input[i - 1] ^ 0x80) | (done == prev_done);
    }

    return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));

}
#endif /* MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS */

#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)
/*
 * Zeros and len padding: fill with 00 ... 00 ll, where ll is padding length
 */
static void add_zeros_and_len_padding(unsigned char *output,
                                      size_t output_len, size_t data_len)
{
    size_t padding_len = output_len - data_len;
    unsigned char i = 0;

    for (i = 1; i < padding_len; i++) {
        output[data_len + i - 1] = 0x00;
    }
    output[output_len - 1] = (unsigned char) padding_len;
}

static int get_zeros_and_len_padding(unsigned char *input, size_t input_len,
                                     size_t *data_len)
{
    size_t i, pad_idx;
    unsigned char padding_len, bad = 0;

    if (NULL == input || NULL == data_len) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    padding_len = input[input_len - 1];
    *data_len = input_len - padding_len;

    /* Avoid logical || since it results in a branch */
    bad |= padding_len > input_len;
    bad |= padding_len == 0;

    /* The number of bytes checked must be independent of padding_len */
    pad_idx = input_len - padding_len;
    for (i = 0; i < input_len - 1; i++) {
        bad |= input[i] * (i >= pad_idx);
    }

    return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));
}
#endif /* MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN */

#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
/*
 * Zero padding: fill with 00 ... 00
 */
static void add_zeros_padding(unsigned char *output,
                              size_t output_len, size_t data_len)
{
    size_t i;

    for (i = data_len; i < output_len; i++) {
        output[i] = 0x00;
    }
}

static int get_zeros_padding(unsigned char *input, size_t input_len,
                             size_t *data_len)
{
    size_t i;
    unsigned char done = 0, prev_done;

    if (NULL == input || NULL == data_len) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    *data_len = 0;
    for (i = input_len; i > 0; i--) {
        prev_done = done;
        done |= (input[i - 1] != 0);
        *data_len |= i * (done != prev_done);
    }

    return (0);
}
#endif /* MBEDTLS_CIPHER_PADDING_ZEROS */

/*
 * No padding: don't pad :)
 *
 * There is no add_padding function (check for NULL in mbedtls_cipher_finish)
 * but a trivial get_padding function
 */
static int get_no_padding(unsigned char *input, size_t input_len,
                          size_t *data_len)
{
    if (NULL == input || NULL == data_len) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    *data_len = input_len;

    return (0);
}
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

int mbedtls_cipher_finish(mbedtls_cipher_context_t *ctx,
                          unsigned char *output, size_t *olen)
{
    if (NULL == ctx || NULL == ctx->cipher_info || NULL == olen) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    *olen = 0;

    if (MBEDTLS_MODE_CFB == ctx->cipher_info->mode ||
        MBEDTLS_MODE_CTR == ctx->cipher_info->mode ||
        MBEDTLS_MODE_GCM == ctx->cipher_info->mode ||
        MBEDTLS_MODE_STREAM == ctx->cipher_info->mode) {
        return (0);
    }

    if (MBEDTLS_MODE_ECB == ctx->cipher_info->mode) {
        if (ctx->unprocessed_len != 0) {
            return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
        }

        return (0);
    }

#if defined(MBEDTLS_CIPHER_MODE_CBC)
    if (MBEDTLS_MODE_CBC == ctx->cipher_info->mode) {
        int ret = 0;

        if (MBEDTLS_ENCRYPT == ctx->operation) {
            /* check for 'no padding' mode */
            if (NULL == ctx->add_padding) {
                if (0 != ctx->unprocessed_len) {
                    return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
                }

                return (0);
            }

            ctx->add_padding(ctx->unprocessed_data, mbedtls_cipher_get_iv_size(ctx),
                             ctx->unprocessed_len);
        } else if (mbedtls_cipher_get_block_size(ctx) != ctx->unprocessed_len) {
            /*
             * For decrypt operations, expect a full block,
             * or an empty block if no padding
             */
            if (NULL == ctx->add_padding && 0 == ctx->unprocessed_len) {
                return (0);
            }

            return (MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED);
        }

        /* cipher block */
        if (0 != (ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx,
                        ctx->operation, mbedtls_cipher_get_block_size(ctx), ctx->iv,
                        ctx->unprocessed_data, output))) {
            return (ret);
        }

        /* Set output size for decryption */
        if (MBEDTLS_DECRYPT == ctx->operation)
            return ctx->get_padding(output, mbedtls_cipher_get_block_size(ctx),
                                    olen);

        /* Set output size for encryption */
        *olen = mbedtls_cipher_get_block_size(ctx);
        return (0);
    }
#else
    ((void) output);
#endif /* MBEDTLS_CIPHER_MODE_CBC */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
int mbedtls_cipher_set_padding_mode(mbedtls_cipher_context_t *ctx, mbedtls_cipher_padding_t mode)
{
    if (NULL == ctx ||
        MBEDTLS_MODE_CBC != ctx->cipher_info->mode) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    switch (mode) {
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
    case MBEDTLS_PADDING_PKCS7:
        ctx->add_padding = add_pkcs_padding;
        ctx->get_padding = get_pkcs_padding;
        break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)
    case MBEDTLS_PADDING_ONE_AND_ZEROS:
        ctx->add_padding = add_one_and_zeros_padding;
        ctx->get_padding = get_one_and_zeros_padding;
        break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)
    case MBEDTLS_PADDING_ZEROS_AND_LEN:
        ctx->add_padding = add_zeros_and_len_padding;
        ctx->get_padding = get_zeros_and_len_padding;
        break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
    case MBEDTLS_PADDING_ZEROS:
        ctx->add_padding = add_zeros_padding;
        ctx->get_padding = get_zeros_padding;
        break;
#endif
    case MBEDTLS_PADDING_NONE:
        ctx->add_padding = NULL;
        ctx->get_padding = get_no_padding;
        break;

    default:
        return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
    }

    return (0);
}
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

#if defined(MBEDTLS_GCM_C)
int mbedtls_cipher_write_tag(mbedtls_cipher_context_t *ctx,
                             unsigned char *tag, size_t tag_len)
{
    if (NULL == ctx || NULL == ctx->cipher_info || NULL == tag) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    if (MBEDTLS_ENCRYPT != ctx->operation) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
        return mbedtls_gcm_finish((mbedtls_gcm_context *) ctx->cipher_ctx, tag, tag_len);
    }

    return (0);
}

int mbedtls_cipher_check_tag(mbedtls_cipher_context_t *ctx,
                             const unsigned char *tag, size_t tag_len)
{
    int ret;

    if (NULL == ctx || NULL == ctx->cipher_info ||
        MBEDTLS_DECRYPT != ctx->operation) {
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
    }

    if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
        unsigned char check_tag[16];
        size_t i;
        int diff;

        if (tag_len > sizeof(check_tag)) {
            return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);
        }

        if (0 != (ret = mbedtls_gcm_finish((mbedtls_gcm_context *) ctx->cipher_ctx,
                                           check_tag, tag_len))) {
            return (ret);
        }

        /* Check the tag in "constant-time" */
        for (diff = 0, i = 0; i < tag_len; i++) {
            diff |= tag[i] ^ check_tag[i];
        }

        if (diff != 0) {
            return (MBEDTLS_ERR_CIPHER_AUTH_FAILED);
        }

        return (0);
    }

    return (0);
}
#endif /* MBEDTLS_GCM_C */

/*
 * Packet-oriented wrapper for non-AEAD modes
 */
int mbedtls_cipher_crypt(mbedtls_cipher_context_t *ctx,
                         const unsigned char *iv, size_t iv_len,
                         const unsigned char *input, size_t ilen,
                         unsigned char *output, size_t *olen)
{
    int ret;
    size_t finish_olen;

    if ((ret = mbedtls_cipher_set_iv(ctx, iv, iv_len)) != 0) {
        return (ret);
    }

    if ((ret = mbedtls_cipher_reset(ctx)) != 0) {
        return (ret);
    }

    if ((ret = mbedtls_cipher_update(ctx, input, ilen, output, olen)) != 0) {
        return (ret);
    }

    if ((ret = mbedtls_cipher_finish(ctx, output + *olen, &finish_olen)) != 0) {
        return (ret);
    }

    *olen += finish_olen;

    return (0);
}

#if defined(MBEDTLS_CIPHER_MODE_AEAD)
/*
 * Packet-oriented encryption for AEAD modes
 */
int mbedtls_cipher_auth_encrypt(mbedtls_cipher_context_t *ctx,
                                const unsigned char *iv, size_t iv_len,
                                const unsigned char *ad, size_t ad_len,
                                const unsigned char *input, size_t ilen,
                                unsigned char *output, size_t *olen,
                                unsigned char *tag, size_t tag_len)
{
#if defined(MBEDTLS_GCM_C)
    if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
        *olen = ilen;
        return (mbedtls_gcm_crypt_and_tag(ctx->cipher_ctx, MBEDTLS_GCM_ENCRYPT, ilen,
                                          iv, iv_len, ad, ad_len, input, output,
                                          tag_len, tag));
    }
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
    if (MBEDTLS_MODE_CCM == ctx->cipher_info->mode) {
        *olen = ilen;
        return (mbedtls_ccm_encrypt_and_tag(ctx->cipher_ctx, ilen,
                                            iv, iv_len, ad, ad_len, input, output,
                                            tag, tag_len));
    }
#endif /* MBEDTLS_CCM_C */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

/*
 * Packet-oriented decryption for AEAD modes
 */
int mbedtls_cipher_auth_decrypt(mbedtls_cipher_context_t *ctx,
                                const unsigned char *iv, size_t iv_len,
                                const unsigned char *ad, size_t ad_len,
                                const unsigned char *input, size_t ilen,
                                unsigned char *output, size_t *olen,
                                const unsigned char *tag, size_t tag_len)
{
#if defined(MBEDTLS_GCM_C)
    if (MBEDTLS_MODE_GCM == ctx->cipher_info->mode) {
        int ret;

        *olen = ilen;
        ret = mbedtls_gcm_auth_decrypt(ctx->cipher_ctx, ilen,
                                       iv, iv_len, ad, ad_len,
                                       tag, tag_len, input, output);

        if (ret == MBEDTLS_ERR_GCM_AUTH_FAILED) {
            ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
        }

        return (ret);
    }
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
    if (MBEDTLS_MODE_CCM == ctx->cipher_info->mode) {
        int ret;

        *olen = ilen;
        ret = mbedtls_ccm_auth_decrypt(ctx->cipher_ctx, ilen,
                                       iv, iv_len, ad, ad_len,
                                       input, output, tag, tag_len);

        if (ret == MBEDTLS_ERR_CCM_AUTH_FAILED) {
            ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
        }

        return (ret);
    }
#endif /* MBEDTLS_CCM_C */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}
#endif /* MBEDTLS_CIPHER_MODE_AEAD */

#endif /* MBEDTLS_CIPHER_C */