library/pkcs5.c

/**
 * \file pkcs5.c
 *
 * \brief PKCS#5 functions
 *
 * \author Mathias Olsson <mathias@kompetensum.com>
 *
 *  Copyright The Mbed TLS Contributors
 *  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.
 */
/*
 * PKCS#5 includes PBKDF2 and more
 *
 * http://tools.ietf.org/html/rfc2898 (Specification)
 * http://tools.ietf.org/html/rfc6070 (Test vectors)
 */

#include "common.h"

#if defined(MBEDTLS_PKCS5_C)

#include "mbedtls/pkcs5.h"
#include "mbedtls/error.h"

#if defined(MBEDTLS_ASN1_PARSE_C)
#include "mbedtls/asn1.h"
#include "mbedtls/cipher.h"
#include "mbedtls/oid.h"
#endif /* MBEDTLS_ASN1_PARSE_C */

#include <string.h>

#include "mbedtls/platform.h"


#if defined(MBEDTLS_ASN1_PARSE_C)
static int pkcs5_parse_pbkdf2_params(const mbedtls_asn1_buf *params,
                                     mbedtls_asn1_buf *salt, int *iterations,
                                     int *keylen, mbedtls_md_type_t *md_type)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    mbedtls_asn1_buf prf_alg_oid;
    unsigned char *p = params->p;
    const unsigned char *end = params->p + params->len;

    if (params->tag != (MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT,
                                 MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
    }
    /*
     *  PBKDF2-params ::= SEQUENCE {
     *    salt              OCTET STRING,
     *    iterationCount    INTEGER,
     *    keyLength         INTEGER OPTIONAL
     *    prf               AlgorithmIdentifier DEFAULT algid-hmacWithSHA1
     *  }
     *
     */
    if ((ret = mbedtls_asn1_get_tag(&p, end, &salt->len,
                                    MBEDTLS_ASN1_OCTET_STRING)) != 0) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret);
    }

    salt->p = p;
    p += salt->len;

    if ((ret = mbedtls_asn1_get_int(&p, end, iterations)) != 0) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret);
    }

    if (p == end) {
        return 0;
    }

    if ((ret = mbedtls_asn1_get_int(&p, end, keylen)) != 0) {
        if (ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG) {
            return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret);
        }
    }

    if (p == end) {
        return 0;
    }

    if ((ret = mbedtls_asn1_get_alg_null(&p, end, &prf_alg_oid)) != 0) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret);
    }

    if (mbedtls_oid_get_md_hmac(&prf_alg_oid, md_type) != 0) {
        return MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE;
    }

    if (p != end) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT,
                                 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
    }

    return 0;
}

#if !defined(MBEDTLS_CIPHER_PADDING_PKCS7)
int mbedtls_pkcs5_pbes2_ext(const mbedtls_asn1_buf *pbe_params, int mode,
                            const unsigned char *pwd,  size_t pwdlen,
                            const unsigned char *data, size_t datalen,
                            unsigned char *output, size_t output_size,
                            size_t *output_len);
#endif

int mbedtls_pkcs5_pbes2(const mbedtls_asn1_buf *pbe_params, int mode,
                        const unsigned char *pwd,  size_t pwdlen,
                        const unsigned char *data, size_t datalen,
                        unsigned char *output)
{
    size_t output_len = 0;

    /* We assume caller of the function is providing a big enough output buffer
     * so we pass output_size as SIZE_MAX to pass checks, However, no guarantees
     * for the output size actually being correct.
     */
    return mbedtls_pkcs5_pbes2_ext(pbe_params, mode, pwd, pwdlen, data,
                                   datalen, output, SIZE_MAX, &output_len);
}

int mbedtls_pkcs5_pbes2_ext(const mbedtls_asn1_buf *pbe_params, int mode,
                            const unsigned char *pwd,  size_t pwdlen,
                            const unsigned char *data, size_t datalen,
                            unsigned char *output, size_t output_size,
                            size_t *output_len)
{
    int ret, iterations = 0, keylen = 0;
    unsigned char *p, *end;
    mbedtls_asn1_buf kdf_alg_oid, enc_scheme_oid, kdf_alg_params, enc_scheme_params;
    mbedtls_asn1_buf salt;
    mbedtls_md_type_t md_type = MBEDTLS_MD_SHA1;
    unsigned char key[32], iv[32];
    const mbedtls_md_info_t *md_info;
    const mbedtls_cipher_info_t *cipher_info;
    mbedtls_md_context_t md_ctx;
    mbedtls_cipher_type_t cipher_alg;
    mbedtls_cipher_context_t cipher_ctx;
    unsigned int padlen = 0;

    p = pbe_params->p;
    end = p + pbe_params->len;

    /*
     *  PBES2-params ::= SEQUENCE {
     *    keyDerivationFunc AlgorithmIdentifier {{PBES2-KDFs}},
     *    encryptionScheme AlgorithmIdentifier {{PBES2-Encs}}
     *  }
     */
    if (pbe_params->tag != (MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT,
                                 MBEDTLS_ERR_ASN1_UNEXPECTED_TAG);
    }

    if ((ret = mbedtls_asn1_get_alg(&p, end, &kdf_alg_oid,
                                    &kdf_alg_params)) != 0) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret);
    }

    // Only PBKDF2 supported at the moment
    //
    if (MBEDTLS_OID_CMP(MBEDTLS_OID_PKCS5_PBKDF2, &kdf_alg_oid) != 0) {
        return MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE;
    }

    if ((ret = pkcs5_parse_pbkdf2_params(&kdf_alg_params,
                                         &salt, &iterations, &keylen,
                                         &md_type)) != 0) {
        return ret;
    }

    md_info = mbedtls_md_info_from_type(md_type);
    if (md_info == NULL) {
        return MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE;
    }

    if ((ret = mbedtls_asn1_get_alg(&p, end, &enc_scheme_oid,
                                    &enc_scheme_params)) != 0) {
        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret);
    }

    if (mbedtls_oid_get_cipher_alg(&enc_scheme_oid, &cipher_alg) != 0) {
        return MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE;
    }

    cipher_info = mbedtls_cipher_info_from_type(cipher_alg);
    if (cipher_info == NULL) {
        return MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE;
    }

    /*
     * The value of keylen from pkcs5_parse_pbkdf2_params() is ignored
     * since it is optional and we don't know if it was set or not
     */
    keylen = cipher_info->key_bitlen / 8;

    if (enc_scheme_params.tag != MBEDTLS_ASN1_OCTET_STRING ||
        enc_scheme_params.len != cipher_info->iv_size) {
        return MBEDTLS_ERR_PKCS5_INVALID_FORMAT;
    }

    if (mode == MBEDTLS_PKCS5_DECRYPT) {
        if (output_size < datalen) {
            return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
        }
    }

    if (mode == MBEDTLS_PKCS5_ENCRYPT) {
        padlen = cipher_info->block_size - (datalen % cipher_info->block_size);
        if (output_size < (datalen + padlen)) {
            return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
        }
    }

    mbedtls_md_init(&md_ctx);

    mbedtls_cipher_init(&cipher_ctx);

    memcpy(iv, enc_scheme_params.p, enc_scheme_params.len);

    if ((ret = mbedtls_md_setup(&md_ctx, md_info, 1)) != 0) {
        goto exit;
    }

    if ((ret = mbedtls_pkcs5_pbkdf2_hmac(&md_ctx, pwd, pwdlen, salt.p, salt.len,
                                         iterations, keylen, key)) != 0) {
        goto exit;
    }

    if ((ret = mbedtls_cipher_setup(&cipher_ctx, cipher_info)) != 0) {
        goto exit;
    }

    if ((ret = mbedtls_cipher_setkey(&cipher_ctx, key, 8 * keylen,
                                     (mbedtls_operation_t) mode)) != 0) {
        goto exit;
    }

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    /* PKCS5 uses CBC with PKCS7 padding (which is the same as
     * "PKCS5 padding" except that it's typically only called PKCS5
     * with 64-bit-block ciphers).
     */
    mbedtls_cipher_padding_t padding = MBEDTLS_PADDING_PKCS7;
#if !defined(MBEDTLS_CIPHER_PADDING_PKCS7)
    /* For historical reasons, when decrypting, this function works when
     * decrypting even when support for PKCS7 padding is disabled. In this
     * case, it ignores the padding, and so will never report a
     * password mismatch.
     */
    if (mode == MBEDTLS_DECRYPT) {
        padding = MBEDTLS_PADDING_NONE;
    }
#endif
    if ((ret = mbedtls_cipher_set_padding_mode(&cipher_ctx, padding)) != 0) {
        goto exit;
    }
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */
    if ((ret = mbedtls_cipher_crypt(&cipher_ctx, iv, enc_scheme_params.len,
                                    data, datalen, output, output_len)) != 0) {
        ret = MBEDTLS_ERR_PKCS5_PASSWORD_MISMATCH;
    }

exit:
    mbedtls_md_free(&md_ctx);
    mbedtls_cipher_free(&cipher_ctx);

    return ret;
}
#endif /* MBEDTLS_ASN1_PARSE_C */

int mbedtls_pkcs5_pbkdf2_hmac(mbedtls_md_context_t *ctx,
                              const unsigned char *password,
                              size_t plen, const unsigned char *salt, size_t slen,
                              unsigned int iteration_count,
                              uint32_t key_length, unsigned char *output)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    int j;
    unsigned int i;
    unsigned char md1[MBEDTLS_MD_MAX_SIZE];
    unsigned char work[MBEDTLS_MD_MAX_SIZE];
    unsigned char md_size = mbedtls_md_get_size(ctx->md_info);
    size_t use_len;
    unsigned char *out_p = output;
    unsigned char counter[4];

    memset(counter, 0, 4);
    counter[3] = 1;

#if UINT_MAX > 0xFFFFFFFF
    if (iteration_count > 0xFFFFFFFF) {
        return MBEDTLS_ERR_PKCS5_BAD_INPUT_DATA;
    }
#endif

    if ((ret = mbedtls_md_hmac_starts(ctx, password, plen)) != 0) {
        return ret;
    }
    while (key_length) {
        // U1 ends up in work
        //
        if ((ret = mbedtls_md_hmac_update(ctx, salt, slen)) != 0) {
            goto cleanup;
        }

        if ((ret = mbedtls_md_hmac_update(ctx, counter, 4)) != 0) {
            goto cleanup;
        }

        if ((ret = mbedtls_md_hmac_finish(ctx, work)) != 0) {
            goto cleanup;
        }

        if ((ret = mbedtls_md_hmac_reset(ctx)) != 0) {
            goto cleanup;
        }

        memcpy(md1, work, md_size);

        for (i = 1; i < iteration_count; i++) {
            // U2 ends up in md1
            //
            if ((ret = mbedtls_md_hmac_update(ctx, md1, md_size)) != 0) {
                goto cleanup;
            }

            if ((ret = mbedtls_md_hmac_finish(ctx, md1)) != 0) {
                goto cleanup;
            }

            if ((ret = mbedtls_md_hmac_reset(ctx)) != 0) {
                goto cleanup;
            }

            // U1 xor U2
            //
            for (j = 0; j < md_size; j++) {
                work[j] ^= md1[j];
            }
        }

        use_len = (key_length < md_size) ? key_length : md_size;
        memcpy(out_p, work, use_len);

        key_length -= (uint32_t) use_len;
        out_p += use_len;

        for (i = 4; i > 0; i--) {
            if (++counter[i - 1] != 0) {
                break;
            }
        }
    }

cleanup:
    /* Zeroise buffers to clear sensitive data from memory. */
    mbedtls_platform_zeroize(work, MBEDTLS_MD_MAX_SIZE);
    mbedtls_platform_zeroize(md1, MBEDTLS_MD_MAX_SIZE);

    return ret;
}

#if defined(MBEDTLS_SELF_TEST)

#if !defined(MBEDTLS_SHA1_C)
int mbedtls_pkcs5_self_test(int verbose)
{
    if (verbose != 0) {
        mbedtls_printf("  PBKDF2 (SHA1): skipped\n\n");
    }

    return 0;
}
#else

#define MAX_TESTS   6

static const size_t plen_test_data[MAX_TESTS] =
{ 8, 8, 8, 24, 9 };

static const unsigned char password_test_data[MAX_TESTS][32] =
{
    "password",
    "password",
    "password",
    "passwordPASSWORDpassword",
    "pass\0word",
};

static const size_t slen_test_data[MAX_TESTS] =
{ 4, 4, 4, 36, 5 };

static const unsigned char salt_test_data[MAX_TESTS][40] =
{
    "salt",
    "salt",
    "salt",
    "saltSALTsaltSALTsaltSALTsaltSALTsalt",
    "sa\0lt",
};

static const uint32_t it_cnt_test_data[MAX_TESTS] =
{ 1, 2, 4096, 4096, 4096 };

static const uint32_t key_len_test_data[MAX_TESTS] =
{ 20, 20, 20, 25, 16 };

static const unsigned char result_key_test_data[MAX_TESTS][32] =
{
    { 0x0c, 0x60, 0xc8, 0x0f, 0x96, 0x1f, 0x0e, 0x71,
      0xf3, 0xa9, 0xb5, 0x24, 0xaf, 0x60, 0x12, 0x06,
      0x2f, 0xe0, 0x37, 0xa6 },
    { 0xea, 0x6c, 0x01, 0x4d, 0xc7, 0x2d, 0x6f, 0x8c,
      0xcd, 0x1e, 0xd9, 0x2a, 0xce, 0x1d, 0x41, 0xf0,
      0xd8, 0xde, 0x89, 0x57 },
    { 0x4b, 0x00, 0x79, 0x01, 0xb7, 0x65, 0x48, 0x9a,
      0xbe, 0xad, 0x49, 0xd9, 0x26, 0xf7, 0x21, 0xd0,
      0x65, 0xa4, 0x29, 0xc1 },
    { 0x3d, 0x2e, 0xec, 0x4f, 0xe4, 0x1c, 0x84, 0x9b,
      0x80, 0xc8, 0xd8, 0x36, 0x62, 0xc0, 0xe4, 0x4a,
      0x8b, 0x29, 0x1a, 0x96, 0x4c, 0xf2, 0xf0, 0x70,
      0x38 },
    { 0x56, 0xfa, 0x6a, 0xa7, 0x55, 0x48, 0x09, 0x9d,
      0xcc, 0x37, 0xd7, 0xf0, 0x34, 0x25, 0xe0, 0xc3 },
};

int mbedtls_pkcs5_self_test(int verbose)
{
    mbedtls_md_context_t sha1_ctx;
    const mbedtls_md_info_t *info_sha1;
    int ret, i;
    unsigned char key[64];

    mbedtls_md_init(&sha1_ctx);

    info_sha1 = mbedtls_md_info_from_type(MBEDTLS_MD_SHA1);
    if (info_sha1 == NULL) {
        ret = 1;
        goto exit;
    }

    if ((ret = mbedtls_md_setup(&sha1_ctx, info_sha1, 1)) != 0) {
        ret = 1;
        goto exit;
    }

    for (i = 0; i < MAX_TESTS; i++) {
        if (verbose != 0) {
            mbedtls_printf("  PBKDF2 (SHA1) #%d: ", i);
        }

        ret = mbedtls_pkcs5_pbkdf2_hmac(&sha1_ctx, password_test_data[i],
                                        plen_test_data[i], salt_test_data[i],
                                        slen_test_data[i], it_cnt_test_data[i],
                                        key_len_test_data[i], key);
        if (ret != 0 ||
            memcmp(result_key_test_data[i], key, key_len_test_data[i]) != 0) {
            if (verbose != 0) {
                mbedtls_printf("failed\n");
            }

            ret = 1;
            goto exit;
        }

        if (verbose != 0) {
            mbedtls_printf("passed\n");
        }
    }

    if (verbose != 0) {
        mbedtls_printf("\n");
    }

exit:
    mbedtls_md_free(&sha1_ctx);

    return ret;
}
#endif /* MBEDTLS_SHA1_C */

#endif /* MBEDTLS_SELF_TEST */

#endif /* MBEDTLS_PKCS5_C */