/*

 *  PSA cipher driver entry points

 */

/*

 *  Copyright The Mbed TLS Contributors

 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later

 */

#include "common.h"

#if defined(MBEDTLS_PSA_CRYPTO_C)

#include "psa_crypto_cipher.h"

#include "psa_crypto_core.h"

#include "psa_crypto_random_impl.h"

#include "constant_time_internal.h"

#include "mbedtls/cipher.h"

#include "mbedtls/error.h"

#include <string.h>

/* mbedtls_cipher_values_from_psa() below only checks if the proper build symbols

 * are enabled, but it does not provide any compatibility check between them

 * (i.e. if the specified key works with the specified algorithm). This helper

 * function is meant to provide this support.

 * mbedtls_cipher_info_from_psa() might be used for the same purpose, but it

 * requires CIPHER_C to be enabled.

 */

static psa_status_t mbedtls_cipher_validate_values(

    psa_algorithm_t alg,

    psa_key_type_t key_type)

{

    /* Reduce code size - hinting to the compiler about what it can assume allows the compiler to

       eliminate bits of the logic below. */

#if !defined(PSA_WANT_KEY_TYPE_AES)

    MBEDTLS_ASSUME(key_type != PSA_KEY_TYPE_AES);

#endif

#if !defined(PSA_WANT_KEY_TYPE_ARIA)

    MBEDTLS_ASSUME(key_type != PSA_KEY_TYPE_ARIA);

#endif

#if !defined(PSA_WANT_KEY_TYPE_CAMELLIA)

    MBEDTLS_ASSUME(key_type != PSA_KEY_TYPE_CAMELLIA);

#endif

#if !defined(PSA_WANT_KEY_TYPE_CHACHA20)

    MBEDTLS_ASSUME(key_type != PSA_KEY_TYPE_CHACHA20);

#endif

#if !defined(PSA_WANT_KEY_TYPE_DES)

    MBEDTLS_ASSUME(key_type != PSA_KEY_TYPE_DES);

#endif

#if !defined(PSA_WANT_ALG_CCM)

    MBEDTLS_ASSUME(alg != PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 0));

#endif

#if !defined(PSA_WANT_ALG_GCM)

    MBEDTLS_ASSUME(alg != PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_GCM, 0));

#endif

#if !defined(PSA_WANT_ALG_STREAM_CIPHER)

    MBEDTLS_ASSUME(alg != PSA_ALG_STREAM_CIPHER);

#endif

#if !defined(PSA_WANT_ALG_CHACHA20_POLY1305)

    MBEDTLS_ASSUME(alg != PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CHACHA20_POLY1305, 0));

#endif

#if !defined(PSA_WANT_ALG_CCM_STAR_NO_TAG)

    MBEDTLS_ASSUME(alg != PSA_ALG_CCM_STAR_NO_TAG);

#endif

#if !defined(PSA_WANT_ALG_CTR)

    MBEDTLS_ASSUME(alg != PSA_ALG_CTR);

#endif

#if !defined(PSA_WANT_ALG_CFB)

    MBEDTLS_ASSUME(alg != PSA_ALG_CFB);

#endif

#if !defined(PSA_WANT_ALG_OFB)

    MBEDTLS_ASSUME(alg != PSA_ALG_OFB);

#endif

#if !defined(PSA_WANT_ALG_ECB_NO_PADDING)

    MBEDTLS_ASSUME(alg != PSA_ALG_ECB_NO_PADDING);

#endif

#if !defined(PSA_WANT_ALG_CBC_NO_PADDING)

    MBEDTLS_ASSUME(alg != PSA_ALG_CBC_NO_PADDING);

#endif

#if !defined(PSA_WANT_ALG_CBC_PKCS7)

    MBEDTLS_ASSUME(alg != PSA_ALG_CBC_PKCS7);

#endif

#if !defined(PSA_WANT_ALG_CMAC)

    MBEDTLS_ASSUME(alg != PSA_ALG_CMAC);

#endif

    if (alg == PSA_ALG_STREAM_CIPHER ||

        alg == PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CHACHA20_POLY1305, 0)) {

        if (key_type == PSA_KEY_TYPE_CHACHA20) {

            return PSA_SUCCESS;

        }

    }

    if (alg == PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 0) ||

        alg == PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_GCM, 0) ||

        alg == PSA_ALG_CCM_STAR_NO_TAG) {

        if (key_type == PSA_KEY_TYPE_AES ||

            key_type == PSA_KEY_TYPE_ARIA ||

            key_type == PSA_KEY_TYPE_CAMELLIA) {

            return PSA_SUCCESS;

        }

    }

    if (alg == PSA_ALG_CTR ||

        alg == PSA_ALG_CFB ||

        alg == PSA_ALG_OFB ||

        alg == PSA_ALG_XTS ||

        alg == PSA_ALG_ECB_NO_PADDING ||

        alg == PSA_ALG_CBC_NO_PADDING ||

        alg == PSA_ALG_CBC_PKCS7 ||

        alg == PSA_ALG_CMAC) {

        if (key_type == PSA_KEY_TYPE_AES ||

            key_type == PSA_KEY_TYPE_ARIA ||

            key_type == PSA_KEY_TYPE_DES ||

            key_type == PSA_KEY_TYPE_CAMELLIA) {

            return PSA_SUCCESS;

        }

    }

    return PSA_ERROR_NOT_SUPPORTED;

}

psa_status_t mbedtls_cipher_values_from_psa(

    psa_algorithm_t alg,

    psa_key_type_t key_type,

    size_t *key_bits,

    mbedtls_cipher_mode_t *mode,

    mbedtls_cipher_id_t *cipher_id)

{

    mbedtls_cipher_id_t cipher_id_tmp;

    /* Only DES modifies key_bits */

#if !defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)

    (void) key_bits;

#endif

    if (PSA_ALG_IS_AEAD(alg)) {

        alg = PSA_ALG_AEAD_WITH_SHORTENED_TAG(alg, 0);

    }

    if (PSA_ALG_IS_CIPHER(alg) || PSA_ALG_IS_AEAD(alg)) {

        switch (alg) {

#if defined(MBEDTLS_PSA_BUILTIN_ALG_STREAM_CIPHER)

            case PSA_ALG_STREAM_CIPHER:

                *mode = MBEDTLS_MODE_STREAM;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CTR)

            case PSA_ALG_CTR:

                *mode = MBEDTLS_MODE_CTR;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CFB)

            case PSA_ALG_CFB:

                *mode = MBEDTLS_MODE_CFB;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_OFB)

            case PSA_ALG_OFB:

                *mode = MBEDTLS_MODE_OFB;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_ECB_NO_PADDING)

            case PSA_ALG_ECB_NO_PADDING:

                *mode = MBEDTLS_MODE_ECB;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CBC_NO_PADDING)

            case PSA_ALG_CBC_NO_PADDING:

                *mode = MBEDTLS_MODE_CBC;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CBC_PKCS7)

            case PSA_ALG_CBC_PKCS7:

                *mode = MBEDTLS_MODE_CBC;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM_STAR_NO_TAG)

            case PSA_ALG_CCM_STAR_NO_TAG:

                *mode = MBEDTLS_MODE_CCM_STAR_NO_TAG;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CCM)

            case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 0):

                *mode = MBEDTLS_MODE_CCM;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_GCM)

            case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_GCM, 0):

                *mode = MBEDTLS_MODE_GCM;

                break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)

            case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CHACHA20_POLY1305, 0):

                *mode = MBEDTLS_MODE_CHACHAPOLY;

                break;

#endif

            default:

                return PSA_ERROR_NOT_SUPPORTED;

        }

    } else if (alg == PSA_ALG_CMAC) {

        *mode = MBEDTLS_MODE_ECB;

    } else {

        return PSA_ERROR_NOT_SUPPORTED;

    }

    switch (key_type) {

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_AES)

        case PSA_KEY_TYPE_AES:

            cipher_id_tmp = MBEDTLS_CIPHER_ID_AES;

            break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ARIA)

        case PSA_KEY_TYPE_ARIA:

            cipher_id_tmp = MBEDTLS_CIPHER_ID_ARIA;

            break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)

        case PSA_KEY_TYPE_DES:

            /* key_bits is 64 for Single-DES, 128 for two-key Triple-DES,

             * and 192 for three-key Triple-DES. */

            if (*key_bits == 64) {

                cipher_id_tmp = MBEDTLS_CIPHER_ID_DES;

            } else {

                cipher_id_tmp = MBEDTLS_CIPHER_ID_3DES;

            }

            /* mbedtls doesn't recognize two-key Triple-DES as an algorithm,

             * but two-key Triple-DES is functionally three-key Triple-DES

             * with K1=K3, so that's how we present it to mbedtls. */

            if (*key_bits == 128) {

                *key_bits = 192;

            }

            break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_CAMELLIA)

        case PSA_KEY_TYPE_CAMELLIA:

            cipher_id_tmp = MBEDTLS_CIPHER_ID_CAMELLIA;

            break;

#endif

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_CHACHA20)

        case PSA_KEY_TYPE_CHACHA20:

            cipher_id_tmp = MBEDTLS_CIPHER_ID_CHACHA20;

            break;

#endif

        default:

            return PSA_ERROR_NOT_SUPPORTED;

    }

    if (cipher_id != NULL) {

        *cipher_id = cipher_id_tmp;

    }

    return mbedtls_cipher_validate_values(alg, key_type);

}

#if defined(MBEDTLS_CIPHER_C)

const mbedtls_cipher_info_t *mbedtls_cipher_info_from_psa(

    psa_algorithm_t alg,

    psa_key_type_t key_type,

    size_t key_bits,

    mbedtls_cipher_id_t *cipher_id)

{

    mbedtls_cipher_mode_t mode;

    psa_status_t status;

    mbedtls_cipher_id_t cipher_id_tmp = MBEDTLS_CIPHER_ID_NONE;

    status = mbedtls_cipher_values_from_psa(alg, key_type, &key_bits, &mode, &cipher_id_tmp);

    if (status != PSA_SUCCESS) {

        return NULL;

    }

    if (cipher_id != NULL) {

        *cipher_id = cipher_id_tmp;

    }

    return mbedtls_cipher_info_from_values(cipher_id_tmp, (int) key_bits, mode);

}

#endif /* MBEDTLS_CIPHER_C */

#if defined(MBEDTLS_PSA_BUILTIN_CIPHER)

static psa_status_t psa_cipher_setup(

    mbedtls_psa_cipher_operation_t *operation,

    const psa_key_attributes_t *attributes,

    const uint8_t *key_buffer, size_t key_buffer_size,

    psa_algorithm_t alg,

    mbedtls_operation_t cipher_operation)

{

    int ret = 0;

    size_t key_bits;

    const mbedtls_cipher_info_t *cipher_info = NULL;

    psa_key_type_t key_type = attributes->type;

    (void) key_buffer_size;

    mbedtls_cipher_init(&operation->ctx.cipher);

    operation->alg = alg;

    key_bits = attributes->bits;

    cipher_info = mbedtls_cipher_info_from_psa(alg, key_type,

                                               key_bits, NULL);

    if (cipher_info == NULL) {

        return PSA_ERROR_NOT_SUPPORTED;

    }

    ret = mbedtls_cipher_setup(&operation->ctx.cipher, cipher_info);

    if (ret != 0) {

        goto exit;

    }

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)

    if (key_type == PSA_KEY_TYPE_DES && key_bits == 128) {

        /* Two-key Triple-DES is 3-key Triple-DES with K1=K3 */

        uint8_t keys[24];

        memcpy(keys, key_buffer, 16);

        memcpy(keys + 16, key_buffer, 8);

        ret = mbedtls_cipher_setkey(&operation->ctx.cipher,

                                    keys,

                                    192, cipher_operation);

    } else

#endif

    {

        ret = mbedtls_cipher_setkey(&operation->ctx.cipher, key_buffer,

                                    (int) key_bits, cipher_operation);

    }

    if (ret != 0) {

        goto exit;

    }

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CBC_NO_PADDING) || \

    defined(MBEDTLS_PSA_BUILTIN_ALG_CBC_PKCS7)

    switch (alg) {

        case PSA_ALG_CBC_NO_PADDING:

            ret = mbedtls_cipher_set_padding_mode(&operation->ctx.cipher,

                                                  MBEDTLS_PADDING_NONE);

            break;

        case PSA_ALG_CBC_PKCS7:

            ret = mbedtls_cipher_set_padding_mode(&operation->ctx.cipher,

                                                  MBEDTLS_PADDING_PKCS7);

            break;

        default:

            /* The algorithm doesn't involve padding. */

            ret = 0;

            break;

    }

    if (ret != 0) {

        goto exit;

    }

#endif /* MBEDTLS_PSA_BUILTIN_ALG_CBC_NO_PADDING ||

          MBEDTLS_PSA_BUILTIN_ALG_CBC_PKCS7 */

    operation->block_length = (PSA_ALG_IS_STREAM_CIPHER(alg) ? 1 :

                               PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type));

    operation->iv_length = PSA_CIPHER_IV_LENGTH(key_type, alg);

exit:

    return mbedtls_to_psa_error(ret);

}

psa_status_t mbedtls_psa_cipher_encrypt_setup(

    mbedtls_psa_cipher_operation_t *operation,

    const psa_key_attributes_t *attributes,

    const uint8_t *key_buffer, size_t key_buffer_size,

    psa_algorithm_t alg)

{

    return psa_cipher_setup(operation, attributes,

                            key_buffer, key_buffer_size,

                            alg, MBEDTLS_ENCRYPT);

}

psa_status_t mbedtls_psa_cipher_decrypt_setup(

    mbedtls_psa_cipher_operation_t *operation,

    const psa_key_attributes_t *attributes,

    const uint8_t *key_buffer, size_t key_buffer_size,

    psa_algorithm_t alg)

{

    return psa_cipher_setup(operation, attributes,

                            key_buffer, key_buffer_size,

                            alg, MBEDTLS_DECRYPT);

}

psa_status_t mbedtls_psa_cipher_set_iv(

    mbedtls_psa_cipher_operation_t *operation,

    const uint8_t *iv, size_t iv_length)

{

    if (iv_length != operation->iv_length) {

        return PSA_ERROR_INVALID_ARGUMENT;

    }

    return mbedtls_to_psa_error(

        mbedtls_cipher_set_iv(&operation->ctx.cipher,

                              iv, iv_length));

}

#if defined(MBEDTLS_PSA_BUILTIN_ALG_ECB_NO_PADDING)

/** Process input for which the algorithm is set to ECB mode.

 *

 * This requires manual processing, since the PSA API is defined as being

 * able to process arbitrary-length calls to psa_cipher_update() with ECB mode,

 * but the underlying mbedtls_cipher_update only takes full blocks.

 *

 * \param ctx           The mbedtls cipher context to use. It must have been

 *                      set up for ECB.

 * \param[in] input     The input plaintext or ciphertext to process.

 * \param input_length  The number of bytes to process from \p input.

 *                      This does not need to be aligned to a block boundary.

 *                      If there is a partial block at the end of the input,

 *                      it is stored in \p ctx for future processing.

 * \param output        The buffer where the output is written. It must be

 *                      at least `BS * floor((p + input_length) / BS)` bytes

 *                      long, where `p` is the number of bytes in the

 *                      unprocessed partial block in \p ctx (with

 *                      `0 <= p <= BS - 1`) and `BS` is the block size.

 * \param output_length On success, the number of bytes written to \p output.

 *                      \c 0 on error.

 *

 * \return #PSA_SUCCESS or an error from a hardware accelerator

 */

static psa_status_t psa_cipher_update_ecb(

    mbedtls_cipher_context_t *ctx,

    const uint8_t *input,

    size_t input_length,

    uint8_t *output,

    size_t *output_length)

{

    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;

    size_t block_size = mbedtls_cipher_info_get_block_size(ctx->cipher_info);

    size_t internal_output_length = 0;

    *output_length = 0;

    if (input_length == 0) {

        status = PSA_SUCCESS;

        goto exit;

    }

    if (ctx->unprocessed_len > 0) {

        /* Fill up to block size, and run the block if there's a full one. */

        size_t bytes_to_copy = block_size - ctx->unprocessed_len;

        if (input_length < bytes_to_copy) {

            bytes_to_copy = input_length;

        }

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

               input, bytes_to_copy);

        input_length -= bytes_to_copy;

        input += bytes_to_copy;

        ctx->unprocessed_len += bytes_to_copy;

        if (ctx->unprocessed_len == block_size) {

            status = mbedtls_to_psa_error(

                mbedtls_cipher_update(ctx,

                                      ctx->unprocessed_data,

                                      block_size,

                                      output, &internal_output_length));

            if (status != PSA_SUCCESS) {

                goto exit;

            }

            output += internal_output_length;

            *output_length += internal_output_length;

            ctx->unprocessed_len = 0;

        }

    }

    while (input_length >= block_size) {

        /* Run all full blocks we have, one by one */

        status = mbedtls_to_psa_error(

            mbedtls_cipher_update(ctx, input,

                                  block_size,

                                  output, &internal_output_length));

        if (status != PSA_SUCCESS) {

            goto exit;

        }

        input_length -= block_size;

        input += block_size;

        output += internal_output_length;

        *output_length += internal_output_length;

    }

    if (input_length > 0) {

        /* Save unprocessed bytes for later processing */

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

               input, input_length);

        ctx->unprocessed_len += input_length;

    }

    status = PSA_SUCCESS;

exit:

    return status;

}

#endif /* MBEDTLS_PSA_BUILTIN_ALG_ECB_NO_PADDING */

psa_status_t mbedtls_psa_cipher_update(

    mbedtls_psa_cipher_operation_t *operation,

    const uint8_t *input, size_t input_length,

    uint8_t *output, size_t output_size, size_t *output_length)

{

    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;

    size_t expected_output_size;

    if (!PSA_ALG_IS_STREAM_CIPHER(operation->alg)) {

        /* Take the unprocessed partial block left over from previous

         * update calls, if any, plus the input to this call. Remove

         * the last partial block, if any. You get the data that will be

         * output in this call. */

        expected_output_size =

            (operation->ctx.cipher.unprocessed_len + input_length)

            / operation->block_length * operation->block_length;

    } else {

        expected_output_size = input_length;

    }

    if (output_size < expected_output_size) {

        return PSA_ERROR_BUFFER_TOO_SMALL;

    }

#if defined(MBEDTLS_PSA_BUILTIN_ALG_ECB_NO_PADDING)

    if (operation->alg == PSA_ALG_ECB_NO_PADDING) {

        /* mbedtls_cipher_update has an API inconsistency: it will only

         * process a single block at a time in ECB mode. Abstract away that

         * inconsistency here to match the PSA API behaviour. */

        status = psa_cipher_update_ecb(&operation->ctx.cipher,

                                       input,

                                       input_length,

                                       output,

                                       output_length);

    } else

#endif /* MBEDTLS_PSA_BUILTIN_ALG_ECB_NO_PADDING */

    if (input_length == 0) {

        /* There is no input, nothing to be done */

        *output_length = 0;

        status = PSA_SUCCESS;

    } else {

        status = mbedtls_to_psa_error(

            mbedtls_cipher_update(&operation->ctx.cipher, input,

                                  input_length, output, output_length));

        if (*output_length > output_size) {

            return PSA_ERROR_CORRUPTION_DETECTED;

        }

    }

    return status;

}

psa_status_t mbedtls_psa_cipher_finish(

    mbedtls_psa_cipher_operation_t *operation,

    uint8_t *output, size_t output_size, size_t *output_length)

{

    psa_status_t status = PSA_ERROR_GENERIC_ERROR;

    size_t invalid_padding = 0;

    /* We will copy output_size bytes from temp_output_buffer to the

     * output buffer. We can't use *output_length to determine how

     * much to copy because we must not leak that value through timing

     * when doing decryption with unpadding. But the underlying function

     * is not guaranteed to write beyond *output_length. To ensure we don't

     * leak the former content of the stack to the caller, wipe that

     * former content. */

    uint8_t temp_output_buffer[MBEDTLS_MAX_BLOCK_LENGTH] = { 0 };

    if (output_size > sizeof(temp_output_buffer)) {

        output_size = sizeof(temp_output_buffer);

    }

    if (operation->ctx.cipher.unprocessed_len != 0) {

        if (operation->alg == PSA_ALG_ECB_NO_PADDING ||

            operation->alg == PSA_ALG_CBC_NO_PADDING) {

            status = PSA_ERROR_INVALID_ARGUMENT;

            goto exit;

        }

    }

    status = mbedtls_to_psa_error(

        mbedtls_cipher_finish_padded(&operation->ctx.cipher,

                                     temp_output_buffer,

                                     output_length,

                                     &invalid_padding));

    if (status != PSA_SUCCESS) {

        goto exit;

    }

    if (output_size == 0) {

        ; /* Nothing to copy. Note that output may be NULL in this case. */

    } else {

        /* Do not use the value of *output_length to determine how much

         * to copy. When decrypting a padded cipher, the output length is

         * sensitive, and leaking it could allow a padding oracle attack. */

        memcpy(output, temp_output_buffer, output_size);

    }

    status = mbedtls_ct_error_if_else_0(invalid_padding,

                                        PSA_ERROR_INVALID_PADDING);

    mbedtls_ct_condition_t buffer_too_small =

        mbedtls_ct_uint_lt(output_size, *output_length);

    status = mbedtls_ct_error_if(buffer_too_small,

                                 PSA_ERROR_BUFFER_TOO_SMALL,

                                 status);

exit:

    mbedtls_platform_zeroize(temp_output_buffer,

                             sizeof(temp_output_buffer));

    return status;

}

psa_status_t mbedtls_psa_cipher_abort(

    mbedtls_psa_cipher_operation_t *operation)

{

    /* Sanity check (shouldn't happen: operation->alg should

     * always have been initialized to a valid value). */

    if (!PSA_ALG_IS_CIPHER(operation->alg)) {

        return PSA_ERROR_BAD_STATE;

    }

    mbedtls_cipher_free(&operation->ctx.cipher);

    return PSA_SUCCESS;

}

psa_status_t mbedtls_psa_cipher_encrypt(

    const psa_key_attributes_t *attributes,

    const uint8_t *key_buffer,

    size_t key_buffer_size,

    psa_algorithm_t alg,

    const uint8_t *iv,

    size_t iv_length,

    const uint8_t *input,

    size_t input_length,

    uint8_t *output,

    size_t output_size,

    size_t *output_length)

{

    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;

    mbedtls_psa_cipher_operation_t operation = MBEDTLS_PSA_CIPHER_OPERATION_INIT;

    size_t update_output_length, finish_output_length;

    status = mbedtls_psa_cipher_encrypt_setup(&operation, attributes,

                                              key_buffer, key_buffer_size,

                                              alg);

    if (status != PSA_SUCCESS) {

        goto exit;

    }

    if (iv_length > 0) {

        status = mbedtls_psa_cipher_set_iv(&operation, iv, iv_length);

        if (status != PSA_SUCCESS) {

            goto exit;

        }

    }

    status = mbedtls_psa_cipher_update(&operation, input, input_length,

                                       output, output_size,

                                       &update_output_length);

    if (status != PSA_SUCCESS) {

        goto exit;

    }

    status = mbedtls_psa_cipher_finish(

        &operation,

        mbedtls_buffer_offset(output, update_output_length),

        output_size - update_output_length, &finish_output_length);

    if (status != PSA_SUCCESS) {

        goto exit;

    }

    *output_length = update_output_length + finish_output_length;

exit:

    if (status == PSA_SUCCESS) {

        status = mbedtls_psa_cipher_abort(&operation);

    } else {

        mbedtls_psa_cipher_abort(&operation);

    }

    return status;

}

psa_status_t mbedtls_psa_cipher_decrypt(

    const psa_key_attributes_t *attributes,

    const uint8_t *key_buffer,

    size_t key_buffer_size,

    psa_algorithm_t alg,

    const uint8_t *input,

    size_t input_length,

    uint8_t *output,

    size_t output_size,

    size_t *output_length)

{

    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;

    mbedtls_psa_cipher_operation_t operation = MBEDTLS_PSA_CIPHER_OPERATION_INIT;

    size_t olength, accumulated_length;

    status = mbedtls_psa_cipher_decrypt_setup(&operation, attributes,

                                              key_buffer, key_buffer_size,

                                              alg);

    if (status != PSA_SUCCESS) {

        goto exit;

    }

    if (operation.iv_length > 0) {

        status = mbedtls_psa_cipher_set_iv(&operation,

                                           input, operation.iv_length);

        if (status != PSA_SUCCESS) {

            goto exit;

        }

    }

    status = mbedtls_psa_cipher_update(

        &operation,

        mbedtls_buffer_offset_const(input, operation.iv_length),

        input_length - operation.iv_length,

        output, output_size, &olength);

    if (status != PSA_SUCCESS) {

        goto exit;

    }

    accumulated_length = olength;

    status = mbedtls_psa_cipher_finish(

        &operation,

        mbedtls_buffer_offset(output, accumulated_length),

        output_size - accumulated_length, &olength);

    *output_length = accumulated_length + olength;

exit:

    /* C99 doesn't allow a declaration to follow a label */;

    psa_status_t abort_status = mbedtls_psa_cipher_abort(&operation);

    /* Normally abort shouldn't fail unless the operation is in a bad

     * state, in which case we'd expect finish to fail with the same error.

     * So it doesn't matter much which call's error code we pick when both

     * fail. However, in unauthenticated decryption specifically, the

     * distinction between PSA_SUCCESS and PSA_ERROR_INVALID_PADDING is

     * security-sensitive (risk of a padding oracle attack), so here we

     * must not have a code path that depends on the value of status. */

    if (abort_status != PSA_SUCCESS) {

        status = abort_status;

    }

    return status;

}

#endif /* MBEDTLS_PSA_BUILTIN_CIPHER */

#endif /* MBEDTLS_PSA_CRYPTO_C */