This GitHub repository contains a standard implementation of the Advanced Encryption Standard (AES) with a focus on AES-128 ECB (Electronic Codebook) encryption. AES-128 is a widely adopted encryption standard known for its security and efficiency.
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AES-128 ECB: This implementation adheres to the AES-128 ECB encryption mode, which encrypts individual 16-byte blocks of data independently.
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Fixed Block Size: The algorithm enforces a fixed block size of 16 bytes, and it does not support padding. Input data must be exactly 16 bytes in length for each block.
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Compatibility: Data encrypted using this standard AES-128 ECB algorithm can be decrypted using any compliant AES-128 ECB decryption implementation.
To utilize this standard AES-128 ECB implementation, follow the instructions provided below:
Before utilizing the AES encryption and decryption functions, ensure that you've included the "AES_128_ECB.h" header in your code. This header provides access to the AES functionality.
#include "AES_128_ECB.h"To perform AES encryption and decryption, you must initialize an AES context. This context serves as a container for maintaining the encryption and decryption state.
AES_CTX ctx;To perform encryption, initialize the AES context and provide the encryption key.
AES_EncryptInit(&ctx, key);The AES encryption function allows you to encrypt a single blocks of data, and this implementation does not support padding. Ensure that you provide data blocks of precisely 16 bytes.
AES_Encrypt(&ctx, plaintext, ciphertext);To perform decryption, initialize the AES context with the same key used for encryption.
AES_DecryptInit(&ctx, key);The AES decryption function allows you to decrypt a single blocks of data, and this implementation does not support padding. Ensure that you provide ciphertext blocks of precisely 16 bytes.
AES_Decrypt(&ctx, ciphertext, plaintext);After you have finished using the AES encryption and decryption functions and no longer require the AES context, it's essential to clear sensitive information from memory. Use the following function to achieve this:
AES_CTX_Free(&ctx);Here's an example code snippet in C for using this standard AES-128 ECB implementation:
#include <stdio.h>
#include "AES_128_ECB.h"
// Function to print the title and hexadecimal representation of data
void output(const char *title, const unsigned char *data, unsigned int size) {
printf("%s", title);
for (unsigned int index = 0; index < size; index++) {
printf("%02X", data[index]);
}
printf("\n");
}
int main(int argc, const char *argv[]) {
// AES-128 key (16 bytes)
unsigned char key[AES_KEY_SIZE] = {
0x49, 0x2F, 0xA8, 0x1E, 0xD7, 0x82, 0x4C, 0x93,
0x36, 0x7B, 0xC1, 0xF8, 0xA0, 0xE5, 0x1A, 0x5D
};
// Data block to be encrypted (16 bytes)
unsigned char data[AES_BLOCK_SIZE] = {
0x54, 0x68, 0x69, 0x73, 0x20, 0x69, 0x73, 0x20,
0x61, 0x6E, 0x20, 0x64, 0x61, 0x74, 0x61, 0x21
};
// Print original data
output("ori: 0x", data, 16);
// Initialize AES context
AES_CTX ctx;
// Initialize encryption with the provided key
AES_EncryptInit(&ctx, key);
// Perform encryption
AES_Encrypt(&ctx, data, data);
// Print encrypted data
output("enc: 0x", data, 16);
// Initialize decryption with the same key
AES_DecryptInit(&ctx, key);
// Perform decryption
AES_Decrypt(&ctx, data, data);
// Print decrypted data
output("dec: 0x", data, 16);
// Clean up: zero out the round key array for security purposes
AES_CTX_Free(&ctx);
return 0;
}Here's an example code snippet in C demonstrating AES-128 ECB encryption and decryption with PKCS#7 padding support:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include "AES_128_ECB.h"
// Encryption data with padding PKCS7
uint32_t EncryptData(uint8_t *data, uint32_t size, const uint8_t *key) {
uint8_t padding_size = AES_BLOCK_SIZE - (size % AES_BLOCK_SIZE);
uint32_t data_size = size + padding_size;
// adding padding value
for (uint8_t index = 0; index < padding_size; index++) {
data[size + index] = padding_size;
}
AES_CTX ctx;
AES_EncryptInit(&ctx, key);
for (uint32_t offset = 0; offset < data_size; offset += AES_BLOCK_SIZE) {
AES_Encrypt(&ctx, data + offset, data + offset);
}
AES_CTX_Free(&ctx);
return data_size;
}
// Decryption data with padding PKCS7
uint32_t DecryptData(uint8_t *data, uint32_t size, const uint8_t *key) {
AES_CTX ctx;
AES_DecryptInit(&ctx, key);
for (uint32_t offset = 0; offset < size; offset += AES_BLOCK_SIZE) {
AES_Decrypt(&ctx, data + offset, data + offset);
}
AES_CTX_Free(&ctx);
return size - data[size - 1];
}
void output(const char *title, const uint8_t *data, unsigned int size) {
printf("%s", title);
for (unsigned int index = 0; index < size; index++) {
printf("%02X", data[index]);
}
printf("\n");
}
int main(int argc, const char *argv[]) {
uint8_t data[32];
uint8_t key[16];
int data_len = 0;
memcpy(data, "halloweeks", 10);
memset(key, 0x69, 16);
data_len = 10; // original data length
output("ori: 0x", data, data_len);
data_len = EncryptData(data, data_len, key);
output("enc: 0x", data, data_len);
data_len = DecryptData(data, data_len, key);
output("dec: 0x", data, data_len);
return 0;
}Contributions and feedback are welcome! If you find issues or have ideas for improvements, please open an issue or submit a pull request.
This standard AES-128 ECB implementation is provided under the MIT License.