[c] Implemented the cfich_aes_ctr.c file
Reads passphrase from stdin Encrypt stores salt+iv+ciphertext in the output Decrypt reads the salt,iv,and ciphertext and uses those values
This commit is contained in:
parent
cddc411a19
commit
b9dac186ab
SSH key fingerprint:
SHA256:JiuxZNdA5bRWXPMUJChI0AQ75yC+cXY4xM0IaVwEVys
1 changed files with 247 additions and 0 deletions
247
TPs/TP02/c/src/cfich_aes_ctr.c
Normal file
247
TPs/TP02/c/src/cfich_aes_ctr.c
Normal file
|
|
@ -0,0 +1,247 @@
|
||||||
|
#include <openssl/err.h>
|
||||||
|
#include <openssl/evp.h>
|
||||||
|
#include <openssl/rand.h>
|
||||||
|
#include <stdio.h>
|
||||||
|
#include <stdlib.h>
|
||||||
|
#include <string.h>
|
||||||
|
|
||||||
|
#define KEY_SIZE 32
|
||||||
|
#define SALT_SIZE 16
|
||||||
|
#define ITERATIONS 10000
|
||||||
|
|
||||||
|
int aes_ctr(const char *input_file, const char *output_file, const unsigned char *key, int enc) {
|
||||||
|
|
||||||
|
int BUF_SIZE = 1024;
|
||||||
|
int cipher_block_size = EVP_CIPHER_block_size(EVP_aes_256_ctr());
|
||||||
|
|
||||||
|
int input_size = BUF_SIZE;
|
||||||
|
int output_size = input_size + (cipher_block_size - 1);
|
||||||
|
int u_len = 0, f_len = 0;
|
||||||
|
|
||||||
|
unsigned char input_buf[input_size], output_buf[output_size];
|
||||||
|
|
||||||
|
FILE *finput = fopen(input_file, "rb");
|
||||||
|
if (finput == NULL) {
|
||||||
|
fprintf(stderr, "Error opening input file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
// Open output file
|
||||||
|
FILE *foutput = fopen(output_file, "ab");
|
||||||
|
if (foutput == NULL) {
|
||||||
|
fprintf(stderr, "Error opening output file\n");
|
||||||
|
fclose(finput);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
EVP_CIPHER_CTX *ctx = NULL;
|
||||||
|
if (!(ctx = EVP_CIPHER_CTX_new())) {
|
||||||
|
fprintf(stderr, "Error creating context\n");
|
||||||
|
fclose(finput);
|
||||||
|
fclose(foutput);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
// If enc is 1, then we are encrypting, else we are decrypting
|
||||||
|
// If we are encrypting, we need to generate an IV
|
||||||
|
// If we are decrypting, we need to read the IV from the file
|
||||||
|
unsigned char iv[16];
|
||||||
|
if (enc) {
|
||||||
|
if (RAND_bytes(iv, 16) != 1) {
|
||||||
|
fprintf(stderr, "Error generating IV\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
if (fwrite(iv, 1, 16, foutput) != 16) {
|
||||||
|
fprintf(stderr, "Error writing IV to file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
} else {
|
||||||
|
// Seek forward by 16 bytes to ignore the salt
|
||||||
|
if (fseek(finput, 16, SEEK_SET) != 0) {
|
||||||
|
fprintf(stderr, "Error seeking to IV position in input file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
if (fread(iv, 1, 16, finput) != 16) {
|
||||||
|
fprintf(stderr, "Error reading IV from file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
if (EVP_CipherInit_ex(ctx, EVP_aes_256_ctr(), NULL, key, iv, enc) != 1) {
|
||||||
|
fprintf(stderr, "ERROR: EVP_CipherInit_ex failed. OpenSSL error: %s\n",
|
||||||
|
ERR_error_string(ERR_get_error(), NULL));
|
||||||
|
EVP_CIPHER_CTX_free(ctx);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
int read_size, len;
|
||||||
|
while ((read_size = fread(input_buf, 1, BUF_SIZE, finput)) > 0) {
|
||||||
|
printf("Read %d bytes, passing through CipherUpdate...\n", read_size);
|
||||||
|
if (EVP_CipherUpdate(ctx, output_buf, &len, input_buf, read_size) != 1) {
|
||||||
|
fprintf(stderr, "ERROR: EVP_CipherUpdate failed. OpenSSL error: %s\n",
|
||||||
|
ERR_error_string(ERR_get_error(), NULL));
|
||||||
|
fclose(finput);
|
||||||
|
fclose(foutput);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
printf("\tGot back %d bytes from CipherUpdate...\n", len);
|
||||||
|
printf("Writing %d bytes to %s...\n", len, output_file);
|
||||||
|
if (fwrite(output_buf, 1, len, foutput) != len) {
|
||||||
|
fprintf(stderr, "Error writing to output file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
printf("\tWrote %d bytes\n", len);
|
||||||
|
u_len += len;
|
||||||
|
}
|
||||||
|
if (read_size == -1) {
|
||||||
|
fprintf(stderr, "ERROR: Reading from the file %s failed.\n", input_file);
|
||||||
|
}
|
||||||
|
|
||||||
|
if (EVP_CipherFinal_ex(ctx, output_buf, &f_len) != 1) {
|
||||||
|
fprintf(stderr, "ERROR: EVP_CipherFinal_ex failed. OpenSSL error: %s\n",
|
||||||
|
ERR_error_string(ERR_get_error(), NULL));
|
||||||
|
fclose(finput);
|
||||||
|
fclose(foutput);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
printf("u_len: %d, f_len: %d\n", u_len, f_len);
|
||||||
|
|
||||||
|
if (f_len) {
|
||||||
|
printf("Writing final %d bytes to %s...\n", f_len, output_file);
|
||||||
|
if (fwrite(output_buf, 1, f_len, foutput) != f_len) {
|
||||||
|
fprintf(stderr, "Error writing to output file\n");
|
||||||
|
fclose(finput);
|
||||||
|
fclose(foutput);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
printf("\tWrote last %d bytes\n", f_len);
|
||||||
|
fclose(finput);
|
||||||
|
fclose(foutput);
|
||||||
|
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
int encrypt(char *input_file, const char *passphrase) {
|
||||||
|
unsigned char key[KEY_SIZE];
|
||||||
|
unsigned char salt[SALT_SIZE];
|
||||||
|
// Derive key from passphrase using PBKDF2
|
||||||
|
char *output_file = malloc(strlen(input_file) + 5);
|
||||||
|
strcpy(output_file, input_file);
|
||||||
|
strcat(output_file, ".enc");
|
||||||
|
|
||||||
|
if (RAND_bytes(salt, SALT_SIZE) != 1) {
|
||||||
|
fprintf(stderr, "Error generating salt\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
// Write salt to output file
|
||||||
|
FILE *foutput = fopen(output_file, "wb");
|
||||||
|
if (foutput == NULL) {
|
||||||
|
fprintf(stderr, "Error opening output file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
if (fwrite(salt, 1, 16, foutput) != 16) {
|
||||||
|
fprintf(stderr, "Error writing salt to file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
fclose(foutput);
|
||||||
|
|
||||||
|
// Derive key from passphrase using PBKDF2
|
||||||
|
if (PKCS5_PBKDF2_HMAC(passphrase, strlen(passphrase), salt, SALT_SIZE, ITERATIONS, EVP_sha256(),
|
||||||
|
KEY_SIZE, key) != 1) {
|
||||||
|
fprintf(stderr, "Error deriving key from passphrase\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
// Print salt and key
|
||||||
|
printf("Salt: ");
|
||||||
|
for (int i = 0; i < SALT_SIZE; i++) {
|
||||||
|
printf("%02x", salt[i]);
|
||||||
|
}
|
||||||
|
printf("\n");
|
||||||
|
printf("Key: ");
|
||||||
|
for (int i = 0; i < KEY_SIZE; i++) {
|
||||||
|
printf("%02x", key[i]);
|
||||||
|
}
|
||||||
|
printf("\n");
|
||||||
|
|
||||||
|
aes_ctr(input_file, output_file, key, 1);
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
int decrypt(char *input_file, const char *passphrase) {
|
||||||
|
unsigned char key[KEY_SIZE];
|
||||||
|
unsigned char salt[SALT_SIZE];
|
||||||
|
// Derive key from passphrase using PBKDF2
|
||||||
|
char *output_file = malloc(strlen(input_file) + 5);
|
||||||
|
strcpy(output_file, input_file);
|
||||||
|
strcat(output_file, ".dec");
|
||||||
|
// Read salt from input file
|
||||||
|
FILE *finput = fopen(input_file, "rb");
|
||||||
|
if (finput == NULL) {
|
||||||
|
fprintf(stderr, "Error opening input file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
if (fread(salt, 1, 16, finput) != 16) {
|
||||||
|
fprintf(stderr, "Error reading salt from file\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
fclose(finput);
|
||||||
|
|
||||||
|
// Derive key from passphrase using PBKDF2
|
||||||
|
if (PKCS5_PBKDF2_HMAC(passphrase, strlen(passphrase), salt, SALT_SIZE, ITERATIONS, EVP_sha256(),
|
||||||
|
KEY_SIZE, key) != 1) {
|
||||||
|
fprintf(stderr, "Error deriving key from passphrase\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
// Print salt and key
|
||||||
|
printf("Salt: ");
|
||||||
|
for (int i = 0; i < SALT_SIZE; i++) {
|
||||||
|
printf("%02x", salt[i]);
|
||||||
|
}
|
||||||
|
printf("\n");
|
||||||
|
printf("Key: ");
|
||||||
|
for (int i = 0; i < KEY_SIZE; i++) {
|
||||||
|
printf("%02x", key[i]);
|
||||||
|
}
|
||||||
|
printf("\n");
|
||||||
|
|
||||||
|
aes_ctr(input_file, output_file, key, 0);
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
int main(int argc, char *argv[]) {
|
||||||
|
if (argc < 3) {
|
||||||
|
fprintf(stderr, "Usage: %s {enc|dec} [file_path]\n", argv[0]);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
|
||||||
|
char *mode = argv[1];
|
||||||
|
char *input_file = argv[2];
|
||||||
|
|
||||||
|
if (!(strcmp(mode, "enc") == 0 || strcmp(mode, "dec") == 0)) {
|
||||||
|
fprintf(stderr, "Invalid mode. Use 'enc' or 'dec'.\n");
|
||||||
|
}
|
||||||
|
|
||||||
|
if (argc != 3) {
|
||||||
|
fprintf(stderr, "Usage: %s {enc|dec} [file_path]\n", argv[0]);
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
input_file = argv[2];
|
||||||
|
|
||||||
|
char passphrase[256]; // Assuming maximum passphrase length of 255 characters
|
||||||
|
printf("Enter passphrase: ");
|
||||||
|
if (fgets(passphrase, sizeof(passphrase), stdin) == NULL) {
|
||||||
|
fprintf(stderr, "Error reading passphrase from stdin\n");
|
||||||
|
return 1;
|
||||||
|
}
|
||||||
|
passphrase[strcspn(passphrase, "\n")] = '\0'; // Remove trailing newline
|
||||||
|
|
||||||
|
if (strcmp(mode, "enc") == 0) {
|
||||||
|
encrypt(input_file, passphrase);
|
||||||
|
} else {
|
||||||
|
decrypt(input_file, passphrase);
|
||||||
|
}
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
Loading…
Add table
Reference in a new issue