crypt_and_hash.c

/*
 *  \brief  Generic file encryption program using generic wrappers for configured
 *          security.
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

/* Enable definition of fileno() even when compiling with -std=c99. Must be
 * set before mbedtls_config.h, which pulls in glibc's features.h indirectly.
 * Harmless on other platforms. */
#define _POSIX_C_SOURCE 200112L

#include "mbedtls/build_info.h"

#include "mbedtls/platform.h"

#if defined(MBEDTLS_CIPHER_C) && defined(MBEDTLS_MD_C) && \
    defined(MBEDTLS_FS_IO)
#include "mbedtls/cipher.h"
#include "mbedtls/md.h"
#include "mbedtls/platform_util.h"

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

#if defined(_WIN32)
#include <windows.h>
#if !defined(_WIN32_WCE)
#include <io.h>
#endif
#else
#include <sys/types.h>
#include <unistd.h>
#endif

#define MODE_ENCRYPT    0
#define MODE_DECRYPT    1

#define USAGE   \
    "\n  crypt_and_hash <mode> <input filename> <output filename> <cipher> <mbedtls_md> <key>\n" \
    "\n   <mode>: 0 = encrypt, 1 = decrypt\n" \
    "\n  example: crypt_and_hash 0 file file.aes AES-128-CBC SHA1 hex:E76B2413958B00E193\n" \
    "\n"

#if !defined(MBEDTLS_CIPHER_C) || !defined(MBEDTLS_MD_C) || \
    !defined(MBEDTLS_FS_IO)
int main(void)
{
    mbedtls_printf("MBEDTLS_CIPHER_C and/or MBEDTLS_MD_C and/or MBEDTLS_FS_IO not defined.\n");
    mbedtls_exit(0);
}
#else


int main(int argc, char *argv[])
{
    int ret = 1, i;
    unsigned n;
    int exit_code = MBEDTLS_EXIT_FAILURE;
    int mode;
    size_t keylen, ilen, olen;
    FILE *fkey, *fin = NULL, *fout = NULL;

    char *p;
    unsigned char IV[16];
    unsigned char key[512];
    unsigned char digest[MBEDTLS_MD_MAX_SIZE];
    unsigned char buffer[1024];
    unsigned char output[1024];
    unsigned char diff;

    const mbedtls_cipher_info_t *cipher_info;
    const mbedtls_md_info_t *md_info;
    mbedtls_cipher_context_t cipher_ctx;
    mbedtls_md_context_t md_ctx;
    mbedtls_cipher_mode_t cipher_mode;
    unsigned int cipher_block_size;
    unsigned char md_size;
#if defined(_WIN32_WCE)
    long filesize, offset;
#elif defined(_WIN32)
    LARGE_INTEGER li_size;
    __int64 filesize, offset;
#else
    off_t filesize, offset;
#endif

    mbedtls_cipher_init(&cipher_ctx);
    mbedtls_md_init(&md_ctx);

    /*
     * Parse the command-line arguments.
     */
    if (argc != 7) {
        const int *list;

        mbedtls_printf(USAGE);

        mbedtls_printf("Available ciphers:\n");
        list = mbedtls_cipher_list();
        while (*list) {
            cipher_info = mbedtls_cipher_info_from_type(*list);
            mbedtls_printf("  %s\n", mbedtls_cipher_info_get_name(cipher_info));
            list++;
        }

        mbedtls_printf("\nAvailable message digests:\n");
        list = mbedtls_md_list();
        while (*list) {
            md_info = mbedtls_md_info_from_type(*list);
            mbedtls_printf("  %s\n", mbedtls_md_get_name(md_info));
            list++;
        }

        goto exit;
    }

    mode = atoi(argv[1]);

    if (mode != MODE_ENCRYPT && mode != MODE_DECRYPT) {
        mbedtls_fprintf(stderr, "invalid operation mode\n");
        goto exit;
    }

    if (strcmp(argv[2], argv[3]) == 0) {
        mbedtls_fprintf(stderr, "input and output filenames must differ\n");
        goto exit;
    }

    if ((fin = fopen(argv[2], "rb")) == NULL) {
        mbedtls_fprintf(stderr, "fopen(%s,rb) failed\n", argv[2]);
        goto exit;
    }

    if ((fout = fopen(argv[3], "wb+")) == NULL) {
        mbedtls_fprintf(stderr, "fopen(%s,wb+) failed\n", argv[3]);
        goto exit;
    }

    /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
    mbedtls_setbuf(fin, NULL);
    mbedtls_setbuf(fout, NULL);

    /*
     * Read the Cipher and MD from the command line
     */
    cipher_info = mbedtls_cipher_info_from_string(argv[4]);
    if (cipher_info == NULL) {
        mbedtls_fprintf(stderr, "Cipher '%s' not found\n", argv[4]);
        goto exit;
    }
    if ((ret = mbedtls_cipher_setup(&cipher_ctx, cipher_info)) != 0) {
        mbedtls_fprintf(stderr, "mbedtls_cipher_setup failed\n");
        goto exit;
    }

    md_info = mbedtls_md_info_from_string(argv[5]);
    if (md_info == NULL) {
        mbedtls_fprintf(stderr, "Message Digest '%s' not found\n", argv[5]);
        goto exit;
    }

    if (mbedtls_md_setup(&md_ctx, md_info, 1) != 0) {
        mbedtls_fprintf(stderr, "mbedtls_md_setup failed\n");
        goto exit;
    }

    /*
     * Read the secret key from file or command line
     */
    if ((fkey = fopen(argv[6], "rb")) != NULL) {
        keylen = fread(key, 1, sizeof(key), fkey);
        fclose(fkey);
    } else {
        if (memcmp(argv[6], "hex:", 4) == 0) {
            p = &argv[6][4];
            keylen = 0;

            while (sscanf(p, "%02X", (unsigned int *) &n) > 0 &&
                   keylen < (int) sizeof(key)) {
                key[keylen++] = (unsigned char) n;
                p += 2;
            }
        } else {
            keylen = strlen(argv[6]);

            if (keylen > (int) sizeof(key)) {
                keylen = (int) sizeof(key);
            }

            memcpy(key, argv[6], keylen);
        }
    }

#if defined(_WIN32_WCE)
    filesize = fseek(fin, 0L, SEEK_END);
#else
#if defined(_WIN32)
    /*
     * Support large files (> 2Gb) on Win32
     */
    li_size.QuadPart = 0;
    li_size.LowPart  =
        SetFilePointer((HANDLE) _get_osfhandle(_fileno(fin)),
                       li_size.LowPart, &li_size.HighPart, FILE_END);

    if (li_size.LowPart == 0xFFFFFFFF && GetLastError() != NO_ERROR) {
        mbedtls_fprintf(stderr, "SetFilePointer(0,FILE_END) failed\n");
        goto exit;
    }

    filesize = li_size.QuadPart;
#else
    if ((filesize = lseek(fileno(fin), 0, SEEK_END)) < 0) {
        perror("lseek");
        goto exit;
    }
#endif
#endif

    if (fseek(fin, 0, SEEK_SET) < 0) {
        mbedtls_fprintf(stderr, "fseek(0,SEEK_SET) failed\n");
        goto exit;
    }

    md_size = mbedtls_md_get_size(md_info);
    cipher_block_size = mbedtls_cipher_get_block_size(&cipher_ctx);

    if (mode == MODE_ENCRYPT) {
        /*
         * Generate the initialization vector as:
         * IV = MD( filesize || filename )[0..15]
         */
        for (i = 0; i < 8; i++) {
            buffer[i] = (unsigned char) (filesize >> (i << 3));
        }

        p = argv[2];

        if (mbedtls_md_starts(&md_ctx) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_starts() returned error\n");
            goto exit;
        }
        if (mbedtls_md_update(&md_ctx, buffer, 8) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_update() returned error\n");
            goto exit;
        }
        if (mbedtls_md_update(&md_ctx, (unsigned char *) p, strlen(p))
            != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_update() returned error\n");
            goto exit;
        }
        if (mbedtls_md_finish(&md_ctx, digest) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_finish() returned error\n");
            goto exit;
        }

        memcpy(IV, digest, 16);

        /*
         * Append the IV at the beginning of the output.
         */
        if (fwrite(IV, 1, 16, fout) != 16) {
            mbedtls_fprintf(stderr, "fwrite(%d bytes) failed\n", 16);
            goto exit;
        }

        /*
         * Hash the IV and the secret key together 8192 times
         * using the result to setup the AES context and HMAC.
         */
        memset(digest, 0,  32);
        memcpy(digest, IV, 16);

        for (i = 0; i < 8192; i++) {
            if (mbedtls_md_starts(&md_ctx) != 0) {
                mbedtls_fprintf(stderr,
                                "mbedtls_md_starts() returned error\n");
                goto exit;
            }
            if (mbedtls_md_update(&md_ctx, digest, 32) != 0) {
                mbedtls_fprintf(stderr,
                                "mbedtls_md_update() returned error\n");
                goto exit;
            }
            if (mbedtls_md_update(&md_ctx, key, keylen) != 0) {
                mbedtls_fprintf(stderr,
                                "mbedtls_md_update() returned error\n");
                goto exit;
            }
            if (mbedtls_md_finish(&md_ctx, digest) != 0) {
                mbedtls_fprintf(stderr,
                                "mbedtls_md_finish() returned error\n");
                goto exit;
            }

        }

        if (mbedtls_cipher_setkey(&cipher_ctx,
                                  digest,
                                  (int) mbedtls_cipher_info_get_key_bitlen(cipher_info),
                                  MBEDTLS_ENCRYPT) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_setkey() returned error\n");
            goto exit;
        }
        if (mbedtls_cipher_set_iv(&cipher_ctx, IV, 16) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_set_iv() returned error\n");
            goto exit;
        }
        if (mbedtls_cipher_reset(&cipher_ctx) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_reset() returned error\n");
            goto exit;
        }

        if (mbedtls_md_hmac_starts(&md_ctx, digest, 32) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_hmac_starts() returned error\n");
            goto exit;
        }

        /*
         * Encrypt and write the ciphertext.
         */
        for (offset = 0; offset < filesize; offset += cipher_block_size) {
            ilen = ((unsigned int) filesize - offset > cipher_block_size) ?
                   cipher_block_size : (unsigned int) (filesize - offset);

            if (fread(buffer, 1, ilen, fin) != ilen) {
                mbedtls_fprintf(stderr, "fread(%ld bytes) failed\n", (long) ilen);
                goto exit;
            }

            if (mbedtls_cipher_update(&cipher_ctx, buffer, ilen, output, &olen) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_cipher_update() returned error\n");
                goto exit;
            }

            if (mbedtls_md_hmac_update(&md_ctx, output, olen) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_md_hmac_update() returned error\n");
                goto exit;
            }

            if (fwrite(output, 1, olen, fout) != olen) {
                mbedtls_fprintf(stderr, "fwrite(%ld bytes) failed\n", (long) olen);
                goto exit;
            }
        }

        if (mbedtls_cipher_finish(&cipher_ctx, output, &olen) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_finish() returned error\n");
            goto exit;
        }
        if (mbedtls_md_hmac_update(&md_ctx, output, olen) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_hmac_update() returned error\n");
            goto exit;
        }

        if (fwrite(output, 1, olen, fout) != olen) {
            mbedtls_fprintf(stderr, "fwrite(%ld bytes) failed\n", (long) olen);
            goto exit;
        }

        /*
         * Finally write the HMAC.
         */
        if (mbedtls_md_hmac_finish(&md_ctx, digest) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_hmac_finish() returned error\n");
            goto exit;
        }

        if (fwrite(digest, 1, md_size, fout) != md_size) {
            mbedtls_fprintf(stderr, "fwrite(%d bytes) failed\n", md_size);
            goto exit;
        }
    }

    if (mode == MODE_DECRYPT) {
        /*
         *  The encrypted file must be structured as follows:
         *
         *        00 .. 15              Initialization Vector
         *        16 .. 31              Encrypted Block #1
         *           ..
         *      N*16 .. (N+1)*16 - 1    Encrypted Block #N
         *  (N+1)*16 .. (N+1)*16 + n    Hash(ciphertext)
         */
        if (filesize < 16 + md_size) {
            mbedtls_fprintf(stderr, "File too short to be encrypted.\n");
            goto exit;
        }

        if (cipher_block_size == 0) {
            mbedtls_fprintf(stderr, "Invalid cipher block size: 0. \n");
            goto exit;
        }

        /*
         * Check the file size.
         */
        cipher_mode = mbedtls_cipher_info_get_mode(cipher_info);
        if (cipher_mode != MBEDTLS_MODE_GCM &&
            cipher_mode != MBEDTLS_MODE_CTR &&
            cipher_mode != MBEDTLS_MODE_CFB &&
            cipher_mode != MBEDTLS_MODE_OFB &&
            ((filesize - md_size) % cipher_block_size) != 0) {
            mbedtls_fprintf(stderr, "File content not a multiple of the block size (%u).\n",
                            cipher_block_size);
            goto exit;
        }

        /*
         * Subtract the IV + HMAC length.
         */
        filesize -= (16 + md_size);

        /*
         * Read the IV and original filesize modulo 16.
         */
        if (fread(buffer, 1, 16, fin) != 16) {
            mbedtls_fprintf(stderr, "fread(%d bytes) failed\n", 16);
            goto exit;
        }

        memcpy(IV, buffer, 16);

        /*
         * Hash the IV and the secret key together 8192 times
         * using the result to setup the AES context and HMAC.
         */
        memset(digest, 0,  32);
        memcpy(digest, IV, 16);

        for (i = 0; i < 8192; i++) {
            if (mbedtls_md_starts(&md_ctx) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_md_starts() returned error\n");
                goto exit;
            }
            if (mbedtls_md_update(&md_ctx, digest, 32) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_md_update() returned error\n");
                goto exit;
            }
            if (mbedtls_md_update(&md_ctx, key, keylen) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_md_update() returned error\n");
                goto exit;
            }
            if (mbedtls_md_finish(&md_ctx, digest) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_md_finish() returned error\n");
                goto exit;
            }
        }

        if (mbedtls_cipher_setkey(&cipher_ctx,
                                  digest,
                                  (int) mbedtls_cipher_info_get_key_bitlen(cipher_info),
                                  MBEDTLS_DECRYPT) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_setkey() returned error\n");
            goto exit;
        }

        if (mbedtls_cipher_set_iv(&cipher_ctx, IV, 16) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_set_iv() returned error\n");
            goto exit;
        }

        if (mbedtls_cipher_reset(&cipher_ctx) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_reset() returned error\n");
            goto exit;
        }

        if (mbedtls_md_hmac_starts(&md_ctx, digest, 32) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_hmac_starts() returned error\n");
            goto exit;
        }

        /*
         * Decrypt and write the plaintext.
         */
        for (offset = 0; offset < filesize; offset += cipher_block_size) {
            ilen = ((unsigned int) filesize - offset > cipher_block_size) ?
                   cipher_block_size : (unsigned int) (filesize - offset);

            if (fread(buffer, 1, ilen, fin) != ilen) {
                mbedtls_fprintf(stderr, "fread(%u bytes) failed\n",
                                cipher_block_size);
                goto exit;
            }

            if (mbedtls_md_hmac_update(&md_ctx, buffer, ilen) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_md_hmac_update() returned error\n");
                goto exit;
            }
            if (mbedtls_cipher_update(&cipher_ctx, buffer, ilen, output,
                                      &olen) != 0) {
                mbedtls_fprintf(stderr, "mbedtls_cipher_update() returned error\n");
                goto exit;
            }

            if (fwrite(output, 1, olen, fout) != olen) {
                mbedtls_fprintf(stderr, "fwrite(%ld bytes) failed\n", (long) olen);
                goto exit;
            }
        }

        /*
         * Verify the message authentication code.
         */
        if (mbedtls_md_hmac_finish(&md_ctx, digest) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_md_hmac_finish() returned error\n");
            goto exit;
        }

        if (fread(buffer, 1, md_size, fin) != md_size) {
            mbedtls_fprintf(stderr, "fread(%d bytes) failed\n", md_size);
            goto exit;
        }

        /* Use constant-time buffer comparison */
        diff = 0;
        for (i = 0; i < md_size; i++) {
            diff |= digest[i] ^ buffer[i];
        }

        if (diff != 0) {
            mbedtls_fprintf(stderr, "HMAC check failed: wrong key, "
                                    "or file corrupted.\n");
            goto exit;
        }

        /*
         * Write the final block of data
         */
        if (mbedtls_cipher_finish(&cipher_ctx, output, &olen) != 0) {
            mbedtls_fprintf(stderr, "mbedtls_cipher_finish() returned error\n");
            goto exit;
        }

        if (fwrite(output, 1, olen, fout) != olen) {
            mbedtls_fprintf(stderr, "fwrite(%ld bytes) failed\n", (long) olen);
            goto exit;
        }
    }

    exit_code = MBEDTLS_EXIT_SUCCESS;

exit:
    if (fin) {
        fclose(fin);
    }
    if (fout) {
        fclose(fout);
    }

    /* Zeroize all command line arguments to also cover
       the case when the user has missed or reordered some,
       in which case the key might not be in argv[6]. */
    for (i = 0; i < argc; i++) {
        mbedtls_platform_zeroize(argv[i], strlen(argv[i]));
    }

    mbedtls_platform_zeroize(IV,     sizeof(IV));
    mbedtls_platform_zeroize(key,    sizeof(key));
    mbedtls_platform_zeroize(buffer, sizeof(buffer));
    mbedtls_platform_zeroize(output, sizeof(output));
    mbedtls_platform_zeroize(digest, sizeof(digest));

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

    mbedtls_exit(exit_code);
}
#endif /* MBEDTLS_CIPHER_C && MBEDTLS_MD_C && MBEDTLS_FS_IO */