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/*
* Copyright © 2012 Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 3, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranties of
* MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <glib.h>
#include <gcrypt.h>
#include <math.h>
#include "crypt.h"
static gcry_cipher_hd_t
setup_cipher (const gchar * password)
{
gcry_error_t gcryError;
gcry_cipher_hd_t gcryHandle;
const size_t keyLength = gcry_cipher_get_algo_keylen(GCRY_CIPHER_AES);
const size_t blkLength = gcry_cipher_get_algo_blklen(GCRY_CIPHER_AES);
// We are assuming keyLength and blkLength are the same, check it
if (keyLength != blkLength)
return NULL;
char * aesSymKey = malloc(blkLength);
const size_t passwordLength = strlen(password);
strncpy(aesSymKey, password, blkLength);
size_t i;
for (i = passwordLength; i < blkLength; ++i)
aesSymKey[i] = 0;
gcryError = gcry_cipher_open(&gcryHandle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_CBC, 0);
if (gcryError) {
g_warning("gcry_cipher_open failed: %s/%s\n", gcry_strsource(gcryError), gcry_strerror(gcryError));
return NULL;
}
gcryError = gcry_cipher_setkey(gcryHandle, aesSymKey, keyLength);
if (gcryError) {
g_warning("gcry_cipher_setkey failed: %s/%s\n", gcry_strsource(gcryError), gcry_strerror(gcryError));
gcry_cipher_close(gcryHandle);
return NULL;
}
// Use the key as IV too
gcryError = gcry_cipher_setiv(gcryHandle, aesSymKey, blkLength);
if (gcryError) {
g_warning("gcry_cipher_setiv failed: %s/%s\n", gcry_strsource(gcryError), gcry_strerror(gcryError));
gcry_cipher_close(gcryHandle);
return NULL;
}
return gcryHandle;
}
/**
* do_aes_encrypt:
* @origBuffer: text to encrypt. Needs to be null terminated
* @password: password to use. Will be cut/padded with 0 if it exceeds/does not reach the needed length
* @outBufferLength: (out) On success contains the length of the returned buffer
*
* Returns the AES encrypted version of the text. It is responsability of the caller to free it
*/
gchar *
do_aes_encrypt(const gchar *origBuffer, const gchar * password, size_t *outBufferLength)
{
gcry_error_t gcryError;
gcry_cipher_hd_t gcryHandle;
gcryHandle = setup_cipher (password);
if (gcryHandle == NULL) {
return NULL;
}
const size_t blkLength = gcry_cipher_get_algo_blklen(GCRY_CIPHER_AES);
const size_t origBufferLength = strlen(origBuffer);
const size_t bufferLength = ceil((double)origBufferLength / blkLength) * blkLength;
gchar *buffer = malloc(bufferLength);
memcpy(buffer, origBuffer, origBufferLength);
int i;
for (i = origBufferLength; i < bufferLength; ++i)
buffer[i] = 0;
char * encBuffer = malloc(bufferLength);
size_t lengthDone = 0;
while (lengthDone < bufferLength) {
gcryError = gcry_cipher_encrypt(gcryHandle, &encBuffer[lengthDone], blkLength, &buffer[lengthDone], blkLength);
if (gcryError) {
g_warning("gcry_cipher_encrypt failed: %s/%s\n", gcry_strsource(gcryError), gcry_strerror(gcryError));
gcry_cipher_close(gcryHandle);
free(encBuffer);
return NULL;
}
lengthDone += blkLength;
}
gcry_cipher_close(gcryHandle);
*outBufferLength = bufferLength;
return encBuffer;
}
/**
* do_aes_encrypt:
* @encBuffer: encrypted data
* @password: password to use. Will be cut/padded with 0 if it exceeds/does not reach the needed length
* @encBufferLength: Length of encBuffer
*
* Returns the AES decrypted version of the data. It is null terminated. It is responsability of the caller to free it
*/
gchar *
do_aes_decrypt(const gchar *encBuffer, const gchar * password, const size_t encBufferLength)
{
gcry_error_t gcryError;
gcry_cipher_hd_t gcryHandle;
gcryHandle = setup_cipher (password);
if (gcryHandle == NULL) {
return NULL;
}
const size_t blkLength = gcry_cipher_get_algo_blklen(GCRY_CIPHER_AES128);
const size_t bufferLength = encBufferLength;
char * outBuffer = malloc(bufferLength);
size_t lengthDone = 0;
while (lengthDone < bufferLength) {
gcryError = gcry_cipher_decrypt(gcryHandle, &outBuffer[lengthDone], 16, &encBuffer[lengthDone], 16);
if (gcryError)
{
g_warning("gcry_cipher_decrypt failed: %s/%s\n", gcry_strsource(gcryError), gcry_strerror(gcryError));
return NULL;
}
lengthDone += blkLength;
}
gcry_cipher_close(gcryHandle);
char *result = g_strndup(outBuffer, bufferLength);
free(outBuffer);
return result;
}
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