Uni/CSI-ES-2324
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[TP03] Done

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This commit is contained in:
Afonso Franco 2024-03-05 23:39:41 +00:00
parent a6c894ed56
commit c2f25b8c2d
Signed by: afonso
SSH key fingerprint: SHA256:JiuxZNdA5bRWXPMUJChI0AQ75yC+cXY4xM0IaVwEVys
5 changed files with 175 additions and 41 deletions
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142
TPs/TP03/pbenc_aes_ctr_hmac.c
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@ -19,7 +19,7 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
int input_size = BUF_SIZE;
int output_size = input_size + (cipher_block_size - 1);
int u_len = 0, f_len = 0;
int f_len = 0;
unsigned char input_buf[input_size], output_buf[output_size];
@ -45,30 +45,44 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
return 1;
}
// EVP_MAC *mac = EVP_MAC_fetch(NULL, "HMAC", NULL);
// if (!mac) {
// fprintf(stderr, "Error creating HMAC\n");
// fclose(finput);
// fclose(foutput);
// return 1;
// }
//
// EVP_MAC_CTX *hctx = NULL;
// if (!(hctx = EVP_MAC_CTX_new(mac))) {
// fprintf(stderr, "Error creating HMAC context\n");
// fclose(finput);
// fclose(foutput);
// return 1;
// }
// const OSSL_PARAM params[] = {OSSL_PARAM_UTF8_STRING(OSSL_MAC, "SHA256", 0), OSSL_PARAM_END};
EVP_MAC *mac = EVP_MAC_fetch(NULL, "HMAC", NULL);
if (!mac) {
fprintf(stderr, "Error creating HMAC\n");
fclose(finput);
fclose(foutput);
return 1;
}
// Set the digest type to SHA256
// if (EVP_MAC_CTX_set_params(hctx, EVP_sha256()) != 1) {
// fprintf(stderr, "Error setting HMAC digest type\n");
// fclose(finput);
// fclose(foutput);
// return 1;
// }
EVP_MAC_CTX *hctx = NULL;
if (!(hctx = EVP_MAC_CTX_new(mac))) {
fprintf(stderr, "Error creating HMAC context\n");
fclose(finput);
fclose(foutput);
return 1;
}
// Set parameters for HMAC algorithm
OSSL_PARAM params[2], *p = params;
const EVP_MD *md = EVP_sha256();
*p++ = OSSL_PARAM_construct_utf8_string("digest", (char *)EVP_MD_name(md), 0);
*p = OSSL_PARAM_construct_end();
unsigned char *hmac = malloc(32);
unsigned char *mac_input;
if (enc) {
mac_input = output_buf;
} else {
mac_input = input_buf;
}
fseek(finput, 0, SEEK_END);
long file_size = ftell(finput);
rewind(finput);
if (!enc) {
// Remove the size of the SALT, IV and HMAC from the file size
fseek(finput, 32, SEEK_SET);
file_size -= 64;
}
// If enc is 1, then we are encrypting, else we are decrypting
// If we are encrypting, we need to generate an IV
@ -86,6 +100,7 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
} 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;
}
@ -102,7 +117,7 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
return 1;
}
if (EVP_MAC_init(hctx, key, 32, NULL) != 1) {
if (EVP_MAC_init(hctx, key, 32, params) != 1) {
fprintf(stderr, "ERROR: EVP_MAC_init failed. OpenSSL error: %s\n",
ERR_error_string(ERR_get_error(), NULL));
fclose(finput);
@ -110,10 +125,15 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
return 1;
}
int read_size, len;
unsigned char *hmac = (unsigned char *)malloc(32);
while ((read_size = fread(input_buf, 1, BUF_SIZE, finput)) > 0) {
printf("Read %d bytes, passing through CipherUpdate...\n", read_size);
int len;
while (file_size > 0) {
if (file_size < BUF_SIZE) {
BUF_SIZE = file_size;
}
size_t read_size = fread(input_buf, 1, BUF_SIZE, finput);
if (read_size == 0) {
break;
}
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));
@ -121,17 +141,18 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
fclose(foutput);
return 1;
}
printf("\tGot back %d bytes from CipherUpdate...\n", len);
printf("Writing %d bytes to %s...\n", len, output_file);
if (EVP_MAC_update(hctx, mac_input, read_size) != 1) {
fprintf(stderr, "ERROR: EVP_MAC_update failed. OpenSSL error: %s\n",
ERR_error_string(ERR_get_error(), NULL));
fclose(finput);
fclose(foutput);
return 1;
}
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);
file_size -= read_size;
}
if (EVP_CipherFinal_ex(ctx, output_buf, &f_len) != 1) {
@ -141,10 +162,22 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
fclose(foutput);
return 1;
}
printf("u_len: %d, f_len: %d\n", u_len, f_len);
size_t m_len = 0;
if (EVP_MAC_final(hctx, hmac, &m_len, 32) != 1) {
fprintf(stderr, "ERROR: EVP_MAC_final failed. OpenSSL error: %s\n",
ERR_error_string(ERR_get_error(), NULL));
fclose(finput);
fclose(foutput);
return 1;
}
if (m_len != 32) {
fprintf(stderr, "ERROR: HMAC length is not 32\n");
fclose(finput);
fclose(foutput);
return 1;
}
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);
@ -152,7 +185,32 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
return 1;
}
}
printf("\tWrote last %d bytes\n", f_len);
if (enc) {
if (fwrite(hmac, 1, m_len, foutput) != m_len) {
fprintf(stderr, "Error writing HMAC to file\n");
fclose(finput);
fclose(foutput);
return 1;
}
} else {
unsigned char *hmac2 = malloc(32);
if (fread(hmac2, 1, 32, finput) != 32) {
fprintf(stderr, "Error reading HMAC from file\n");
fclose(finput);
fclose(foutput);
return 1;
}
int cmp = memcmp(hmac, hmac2, 32);
if (cmp == 0) {
printf("HMACs match\n");
} else {
fprintf(stderr, "HMACs do not match\n");
fclose(finput);
fclose(foutput);
return 1;
}
}
fclose(finput);
fclose(foutput);
@ -160,7 +218,7 @@ int aes_ctr(const char *input_file, const char *output_file, const unsigned char
}
int encrypt(char *input_file, const char *passphrase) {
unsigned char key[KEY_SIZE];
unsigned char key[KEY_SIZE * 2];
unsigned char salt[SALT_SIZE];
// Derive key from passphrase using PBKDF2
char *output_file = malloc(strlen(input_file) + 5);
@ -184,8 +242,9 @@ int encrypt(char *input_file, const char *passphrase) {
}
fclose(foutput);
int pass_len = strlen(passphrase);
// Derive key from passphrase using PBKDF2
if (PKCS5_PBKDF2_HMAC(passphrase, strlen(passphrase), salt, SALT_SIZE, ITERATIONS, EVP_sha256(),
if (PKCS5_PBKDF2_HMAC(passphrase, pass_len, salt, SALT_SIZE, ITERATIONS, EVP_sha256(),
KEY_SIZE * 2, key) != 1) {
fprintf(stderr, "Error deriving key from passphrase\n");
return 1;
@ -268,6 +327,7 @@ int main(int argc, char *argv[]) {
return 1;
}
enableEcho();
putchar('\n');
passphrase[strcspn(passphrase, "\n")] = '\0'; // Remove trailing newline
int suc = 0;
if (strcmp(mode, "enc") == 0) {