Add simple toy program for encrypting/decrypting files with AES.

This commit is contained in:
Stephen Heumann 2017-07-02 15:24:49 -05:00
parent 60a7aec49c
commit 4e0903a708

78
aescrypt.c Normal file
View File

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "aes.h"
#define BUFFER_SIZE 0x4000
unsigned char inbuf[BUFFER_SIZE];
unsigned char outbuf[BUFFER_SIZE];
unsigned char iv[16] = "abcdefghijklmnop";
int main(int argc, char **argv) {
FILE *infile, *outfile;
size_t count;
char *filename;
struct aes_context context;
int encrypt;
if (argc != 4) {
fprintf(stderr, "wrong number of arguments\n");
exit(EXIT_FAILURE);
}
if (strncmp(argv[1], "-d", 2) == 0) {
encrypt = 0;
} else if (strncmp(argv[1], "-e", 2) == 0) {
encrypt = 1;
}
infile = fopen(argv[3], "rb");
if (infile == NULL) {
fprintf(stderr, "error opening input file\n");
return EXIT_FAILURE;
}
filename = malloc(strlen(argv[3]) + 5);
strcpy(filename, argv[3]);
if (encrypt) {
strcat(filename, ".aes");
} else {
strcat(filename, ".dec");
}
outfile = fopen(filename, "wb");
if (filename == NULL) {
fprintf(stderr, "error opening output file\n");
return EXIT_FAILURE;
}
memcpy(context.data, iv, 16);
strncpy(context.key, argv[2], 32);
aes128_expandkey(&context);
do {
count = fread(inbuf, 1, BUFFER_SIZE, infile);
count = (count + 15) / 16;
if (encrypt) {
aes_cbc_encrypt(&context, inbuf, outbuf, count);
} else {
aes_cbc_decrypt(&context, inbuf, outbuf, count, iv);
if (count != 0)
memcpy(iv, inbuf + (count - 1) * 16, 16);
}
count *= 16;
if (fwrite(outbuf, 1, count, outfile) != count) {
fprintf(stderr, "error writing file\n");
goto finish;
}
} while (count != 0);
finish:
fclose(infile);
fclose(outfile);
free(filename);
}