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Add OMEMO message encryption and decryption

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This commit is contained in:
Paul Fariello
2019-02-26 20:33:06 +01:40
parent b1ae220aa4
commit 0fb27dc496
18 changed files with 681 additions and 35 deletions
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196
src/omemo/crypto.c
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@@ -2,7 +2,9 @@
#include <signal/signal_protocol.h>
#include <signal/signal_protocol_types.h>
#include <sodium.h>
#include <gcrypt.h>
#include "omemo/omemo.h"
#include "omemo/crypto.h"
int
@@ -12,10 +14,12 @@ omemo_crypto_init(void)
return -1;
}
if (crypto_aead_aes256gcm_is_available() == 0) {
if (!gcry_check_version(GCRYPT_VERSION)) {
return -1;
}
gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
return 0;
}
@@ -96,41 +100,195 @@ int
omemo_encrypt_func(signal_buffer **output, int cipher, const uint8_t *key, size_t key_len, const uint8_t *iv, size_t iv_len,
const uint8_t *plaintext, size_t plaintext_len, void *user_data)
{
gcry_cipher_hd_t hd;
unsigned char *padded_plaintext;
unsigned char *ciphertext;
unsigned long long ciphertext_len;
size_t ciphertext_len;
int mode;
int algo;
uint8_t padding = 0;
assert(cipher != SG_CIPHER_AES_GCM_NOPADDING);
assert(key_len == crypto_aead_aes256gcm_KEYBYTES);
assert(iv_len == crypto_aead_aes256gcm_NPUBBYTES);
switch (key_len) {
case 32:
algo = GCRY_CIPHER_AES256;
break;
default:
return OMEMO_ERR_UNSUPPORTED_CRYPTO;
}
ciphertext = malloc(plaintext_len + crypto_aead_aes256gcm_ABYTES);
crypto_aead_aes256gcm_encrypt(ciphertext, &ciphertext_len, plaintext, plaintext_len, NULL, 0, NULL, iv, key);
switch (cipher) {
case SG_CIPHER_AES_CBC_PKCS5:
mode = GCRY_CIPHER_MODE_CBC;
break;
default:
return OMEMO_ERR_UNSUPPORTED_CRYPTO;
}
gcry_cipher_open(&hd, algo, mode, GCRY_CIPHER_SECURE);
gcry_cipher_setkey(hd, key, key_len);
switch (cipher) {
case SG_CIPHER_AES_CBC_PKCS5:
gcry_cipher_setiv(hd, iv, iv_len);
padding = 16 - (plaintext_len % 16);
break;
default:
assert(FALSE);
}
padded_plaintext = malloc(plaintext_len + padding);
memcpy(padded_plaintext, plaintext, plaintext_len);
memset(padded_plaintext + plaintext_len, padding, padding);
ciphertext_len = plaintext_len + padding;
ciphertext = malloc(ciphertext_len);
gcry_cipher_encrypt(hd, ciphertext, ciphertext_len, padded_plaintext, plaintext_len + padding);
*output = signal_buffer_create(ciphertext, ciphertext_len);
free(padded_plaintext);
free(ciphertext);
return 0;
gcry_cipher_close(hd);
return SG_SUCCESS;
}
int
omemo_decrypt_func(signal_buffer **output, int cipher, const uint8_t *key, size_t key_len, const uint8_t *iv, size_t iv_len,
const uint8_t *ciphertext, size_t ciphertext_len, void *user_data)
{
int ret = SG_SUCCESS;
gcry_cipher_hd_t hd;
unsigned char *plaintext;
unsigned long long plaintext_len;
size_t plaintext_len;
int mode;
int algo;
uint8_t padding = 0;
assert(cipher != SG_CIPHER_AES_GCM_NOPADDING);
assert(key_len == crypto_aead_aes256gcm_KEYBYTES);
assert(iv_len == crypto_aead_aes256gcm_NPUBBYTES);
plaintext = malloc(ciphertext_len - crypto_aead_aes256gcm_ABYTES);
if (crypto_aead_aes256gcm_decrypt(plaintext, &plaintext_len, NULL, ciphertext, ciphertext_len, NULL, 0, iv, key) < 0) {
free(plaintext);
return -1;
switch (key_len) {
case 32:
algo = GCRY_CIPHER_AES256;
break;
default:
return OMEMO_ERR_UNSUPPORTED_CRYPTO;
}
*output = signal_buffer_create(plaintext, plaintext_len);
switch (cipher) {
case SG_CIPHER_AES_CBC_PKCS5:
mode = GCRY_CIPHER_MODE_CBC;
break;
default:
return OMEMO_ERR_UNSUPPORTED_CRYPTO;
}
gcry_cipher_open(&hd, algo, mode, GCRY_CIPHER_SECURE);
gcry_cipher_setkey(hd, key, key_len);
switch (cipher) {
case SG_CIPHER_AES_CBC_PKCS5:
gcry_cipher_setiv(hd, iv, iv_len);
break;
default:
assert(FALSE);
}
plaintext_len = ciphertext_len;
plaintext = malloc(plaintext_len);
gcry_cipher_decrypt(hd, plaintext, plaintext_len, ciphertext, ciphertext_len);
switch (cipher) {
case SG_CIPHER_AES_CBC_PKCS5:
padding = plaintext[plaintext_len - 1];
break;
default:
assert(FALSE);
}
int i;
for (i = 0; i < padding; i++) {
if (plaintext[plaintext_len - 1 - i] != padding) {
ret = SG_ERR_UNKNOWN;
goto out;
}
}
*output = signal_buffer_create(plaintext, plaintext_len - padding);
out:
free(plaintext);
return 0;
gcry_cipher_close(hd);
return ret;
}
int
aes128gcm_encrypt(unsigned char *ciphertext, size_t *ciphertext_len, const unsigned char *const plaintext, size_t plaintext_len, const unsigned char *const iv, const unsigned char *const key)
{
gcry_error_t res;
gcry_cipher_hd_t hd;
res = gcry_cipher_open(&hd, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_GCM, GCRY_CIPHER_SECURE);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
res = gcry_cipher_setkey(hd, key, AES128_GCM_KEY_LENGTH);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
res = gcry_cipher_setiv(hd, iv, AES128_GCM_IV_LENGTH);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
res = gcry_cipher_encrypt(hd, ciphertext, *ciphertext_len, plaintext, plaintext_len);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
res = gcry_cipher_gettag(hd, ciphertext + plaintext_len, AES128_GCM_TAG_LENGTH);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
out:
gcry_cipher_close(hd);
return res;
}
int
aes128gcm_decrypt(unsigned char *plaintext, size_t *plaintext_len, const unsigned char *const ciphertext, size_t ciphertext_len, const unsigned char *const iv, const unsigned char *const key)
{
gcry_error_t res;
gcry_cipher_hd_t hd;
res = gcry_cipher_open(&hd, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_GCM, GCRY_CIPHER_SECURE);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
res = gcry_cipher_setkey(hd, key, AES128_GCM_KEY_LENGTH);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
res = gcry_cipher_setiv(hd, iv, AES128_GCM_IV_LENGTH);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
res = gcry_cipher_decrypt(hd, plaintext, *plaintext_len, ciphertext, ciphertext_len);
if (res != GPG_ERR_NO_ERROR) {
goto out;
}
//res = gcry_cipher_checktag(hd, ciphertext + ciphertext_len - AES128_GCM_TAG_LENGTH, AES128_GCM_TAG_LENGTH);
//if (res != GPG_ERR_NO_ERROR) {
// goto out;
//}
out:
gcry_cipher_close(hd);
return res;
}