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Merge pull request #544 from anhu/aes_modes_ctr 

AES modes extravaganza. CTR
pull/552/head
JacobBarthelmeh 2025-12-18 17:07:40 -07:00 committed by GitHub
parent eaff9c5f2c a6ac31c0e9
commit b179722658
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crypto/aes-modes/aes-ctr.c 100644
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/* aes-ctr.c
*
* Copyright (C) 2006-2025 wolfSSL Inc.
*
* This file is part of wolfSSL.
*
* wolfSSL is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* wolfSSL is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
*/
/* AES-CTR Example
* This example demonstrates:
* - One-shot encryption using wc_AesCtrEncrypt()
* - Streaming decryption using wc_AesCtrEncrypt() in chunks
* Note: CTR mode uses same function for encrypt/decrypt and inherently
* supports streaming (no padding required)
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifndef WOLFSSL_USER_SETTINGS
#include <wolfssl/options.h>
#endif
#include <wolfssl/wolfcrypt/settings.h>
#include <wolfssl/wolfcrypt/aes.h>
#include <wolfssl/wolfcrypt/random.h>
#include <wolfssl/wolfcrypt/error-crypt.h>
#if !defined(NO_AES) && defined(WOLFSSL_AES_COUNTER)
#define AES_KEY_SIZE AES_256_KEY_SIZE
/* Small chunk size to demonstrate streaming */
#define CHUNK_SIZE 64
static int read_file(const char* filename, byte** data, word32* dataSz)
{
FILE* fp;
long fileSz;
fp = fopen(filename, "rb");
if (fp == NULL) {
printf("Error: Cannot open file %s\n", filename);
return -1;
}
fseek(fp, 0, SEEK_END);
fileSz = ftell(fp);
fseek(fp, 0, SEEK_SET);
*data = (byte*)malloc(fileSz);
if (*data == NULL) {
fclose(fp);
printf("Error: Memory allocation failed\n");
return -1;
}
*dataSz = (word32)fread(*data, 1, fileSz, fp);
fclose(fp);
return 0;
}
static int write_file(const char* filename, const byte* data, word32 dataSz)
{
FILE* fp;
fp = fopen(filename, "wb");
if (fp == NULL) {
printf("Error: Cannot create file %s\n", filename);
return -1;
}
fwrite(data, 1, dataSz, fp);
fclose(fp);
return 0;
}
/* One-shot encryption */
static int encrypt_file(const char* inFile, const char* outFile,
const byte* key, word32 keySz)
{
Aes aes;
WC_RNG rng;
byte iv[AES_BLOCK_SIZE];
byte* plaintext = NULL;
byte* ciphertext = NULL;
word32 plaintextSz;
int ret;
ret = read_file(inFile, &plaintext, &plaintextSz);
if (ret != 0) return ret;
/* IV + ciphertext */
ciphertext = (byte*)malloc(plaintextSz + AES_BLOCK_SIZE);
if (ciphertext == NULL) {
free(plaintext);
return -1;
}
/* Generate random IV/nonce */
ret = wc_InitRng(&rng);
if (ret != 0) {
free(plaintext);
free(ciphertext);
return ret;
}
ret = wc_RNG_GenerateBlock(&rng, iv, AES_BLOCK_SIZE);
wc_FreeRng(&rng);
if (ret != 0) {
free(plaintext);
free(ciphertext);
return ret;
}
/* Initialize AES */
ret = wc_AesInit(&aes, NULL, INVALID_DEVID);
if (ret != 0) {
free(plaintext);
free(ciphertext);
return ret;
}
ret = wc_AesSetKey(&aes, key, keySz, iv, AES_ENCRYPTION);
if (ret != 0) {
wc_AesFree(&aes);
free(plaintext);
free(ciphertext);
return ret;
}
/* One-shot encrypt */
ret = wc_AesCtrEncrypt(&aes, ciphertext + AES_BLOCK_SIZE, plaintext,
plaintextSz);
wc_AesFree(&aes);
if (ret != 0) {
free(plaintext);
free(ciphertext);
return ret;
}
/* Prepend IV to output */
memcpy(ciphertext, iv, AES_BLOCK_SIZE);
ret = write_file(outFile, ciphertext, plaintextSz + AES_BLOCK_SIZE);
free(plaintext);
free(ciphertext);
printf("AES-CTR encryption complete (one-shot)\n");
return ret;
}
/* Streaming decryption - process in chunks */
static int decrypt_file(const char* inFile, const char* outFile,
const byte* key, word32 keySz)
{
Aes aes;
byte iv[AES_BLOCK_SIZE];
byte* ciphertext = NULL;
byte* plaintext = NULL;
word32 ciphertextSz;
word32 plaintextSz;
word32 offset;
word32 chunkSz;
int ret;
ret = read_file(inFile, &ciphertext, &ciphertextSz);
if (ret != 0) return ret;
if (ciphertextSz < AES_BLOCK_SIZE) {
free(ciphertext);
printf("Error: File too small\n");
return -1;
}
/* Extract IV from beginning */
memcpy(iv, ciphertext, AES_BLOCK_SIZE);
plaintextSz = ciphertextSz - AES_BLOCK_SIZE;
plaintext = (byte*)malloc(plaintextSz);
if (plaintext == NULL) {
free(ciphertext);
return -1;
}
/* Initialize AES */
ret = wc_AesInit(&aes, NULL, INVALID_DEVID);
if (ret != 0) {
free(ciphertext);
free(plaintext);
return ret;
}
ret = wc_AesSetKey(&aes, key, keySz, iv, AES_ENCRYPTION);
if (ret != 0) {
wc_AesFree(&aes);
free(ciphertext);
free(plaintext);
return ret;
}
/* Streaming decrypt - process in chunks
* Note: CTR mode uses same function for encrypt and decrypt */
printf("AES-CTR streaming decryption:\n");
offset = 0;
while (offset < plaintextSz) {
chunkSz = plaintextSz - offset;
if (chunkSz > CHUNK_SIZE) {
chunkSz = CHUNK_SIZE;
}
ret = wc_AesCtrEncrypt(&aes, plaintext + offset,
ciphertext + AES_BLOCK_SIZE + offset, chunkSz);
if (ret != 0) {
wc_AesFree(&aes);
free(ciphertext);
free(plaintext);
return ret;
}
printf(" Decrypted chunk: offset=%u, size=%u\n", offset, chunkSz);
offset += chunkSz;
}
wc_AesFree(&aes);
ret = write_file(outFile, plaintext, plaintextSz);
free(ciphertext);
free(plaintext);
printf("AES-CTR decryption complete (streaming)\n");
return ret;
}
int main(int argc, char** argv)
{
byte key[AES_KEY_SIZE];
int ret;
if (argc != 3) {
printf("Usage: %s <input file> <output file>\n", argv[0]);
printf("Encrypts input file (one-shot), then decrypts to output file (streaming)\n");
return 1;
}
wolfCrypt_Init();
/* Use a fixed key for demonstration */
memset(key, 0x07, AES_KEY_SIZE);
/* Encrypt to temporary file */
ret = encrypt_file(argv[1], "temp_encrypted.bin", key, AES_KEY_SIZE);
if (ret != 0) {
printf("Encryption failed: %d\n", ret);
wolfCrypt_Cleanup();
return 1;
}
/* Decrypt to output file */
ret = decrypt_file("temp_encrypted.bin", argv[2], key, AES_KEY_SIZE);
if (ret != 0) {
printf("Decryption failed: %d\n", ret);
wolfCrypt_Cleanup();
return 1;
}
/* Clean up temp file */
remove("temp_encrypted.bin");
printf("Success! Decrypted file written to %s\n", argv[2]);
wolfCrypt_Cleanup();
return 0;
}
#else
int main(int argc, char** argv)
{
(void)argc;
(void)argv;
printf("AES-CTR not compiled in. Enable with WOLFSSL_AES_COUNTER\n");
return 0;
}
#endif