151 lines
3.4 KiB
C
151 lines
3.4 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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/**
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@file aesgcm.c
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AES128-GCM demo - file en-&decryption, Steffen Jaeckel
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Uses the format: |ciphertext|tag-16-bytes|
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*/
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#define _GNU_SOURCE
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#include <tomcrypt.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <dirent.h>
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#include <string.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "gcm-file/gcm_filehandle.c"
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#include "gcm-file/gcm_file.c"
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static off_t fsize(const char *filename)
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{
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struct stat st;
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if (stat(filename, &st) == 0) return st.st_size;
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return -1;
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}
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#if defined(__linux__) && defined(__GLIBC_PREREQ)
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#if __GLIBC_PREREQ(2, 14)
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#define HAS_SYNCFS
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#endif
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#endif
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static int mv(const char *old_name, const char *new_name)
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{
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int fd;
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if (rename(old_name, new_name) == -1) return -1;
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fd = open(new_name, 0);
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if (fd == -1) return -1;
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#if !defined(_WIN32)
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if (fsync(fd) != 0) goto OUT;
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#if defined(HAS_SYNCFS)
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syncfs(fd);
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#else
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sync();
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#endif
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OUT:
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#endif
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close(fd);
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return 0;
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}
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/* https://stackoverflow.com/a/23898449 */
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static void scan_hex(const char* str, uint8_t* bytes, size_t blen)
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{
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uint8_t pos;
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uint8_t idx0;
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uint8_t idx1;
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const uint8_t hashmap[] =
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{
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0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, /* 01234567 */
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0x08, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 89:;<=>? */
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0x00, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x00, /* @ABCDEFG */
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* HIJKLMNO */
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* PQRSTUVW */
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* XYZ[\]^_ */
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0x00, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x00, /* `abcdefg */
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};
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for (pos = 0; ((pos < (blen*2)) && (pos < XSTRLEN(str))); pos += 2)
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{
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idx0 = (uint8_t)(str[pos+0] & 0x1F) ^ 0x10;
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idx1 = (uint8_t)(str[pos+1] & 0x1F) ^ 0x10;
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bytes[pos/2] = (uint8_t)(hashmap[idx0] << 4) | hashmap[idx1];
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}
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}
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static void die(int ret)
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{
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fprintf(stderr, "Usage: aesgcm <-e|-d> <infile> <outfile> <88|96 char hex-string 'IV | key'>\n");
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exit(ret);
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}
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int main(int argc, char **argv)
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{
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int ret = 0, err, arg, direction, res, tmp;
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size_t keylen;
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uint8_t keybuf[48] = {0};
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char *out = NULL;
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const char *mode, *in_file, *out_file, *key_string;
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unsigned long ivlen;
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if (argc < 5) die(__LINE__);
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arg = 1;
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mode = argv[arg++];
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in_file = argv[arg++];
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out_file = argv[arg++];
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key_string = argv[arg++];
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if(strcmp(mode, "-d") == 0) direction = GCM_DECRYPT;
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else if(strcmp(mode, "-e") == 0) direction = GCM_ENCRYPT;
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else die(__LINE__);
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if (fsize(in_file) <= 0) die(__LINE__);
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keylen = XSTRLEN(key_string);
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if (keylen != 88 && keylen != 96) die(__LINE__);
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scan_hex(key_string, keybuf, keylen/2);
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register_all_ciphers();
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if(asprintf(&out, "%s-XXXXXX", out_file) < 0) die(__LINE__);
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if((tmp = mkstemp(out)) == -1) {
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ret = __LINE__;
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goto cleanup;
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}
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close(tmp);
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ivlen = keylen/2 - 32;
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if((err = gcm_file(find_cipher("aes"), &keybuf[ivlen], 32, keybuf, ivlen, NULL, 0, in_file, out, 16, direction, &res)) != CRYPT_OK) {
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fprintf(stderr, "boooh %s\n", error_to_string(err));
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ret = __LINE__;
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goto cleanup;
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}
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if(res != 1) {
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ret = __LINE__;
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}
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else
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{
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if (mv(out, out_file) != 0) ret = __LINE__;
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}
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cleanup:
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if(ret != 0) unlink(out);
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free(out);
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return ret;
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}
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