https://github.com/roginvs/test_crypto
AES implementation
https://github.com/roginvs/test_crypto
Last synced: 12 months ago
JSON representation
AES implementation
- Host: GitHub
- URL: https://github.com/roginvs/test_crypto
- Owner: roginvs
- Created: 2020-02-19T19:37:36.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2021-03-21T10:14:42.000Z (over 5 years ago)
- Last Synced: 2025-04-06T23:42:39.497Z (about 1 year ago)
- Language: C
- Homepage:
- Size: 1.8 MB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Implementing AES encryption in CBC mode
## Building and testing
```bash
./build-and-test.sh
```
## Using in command-line mode
Only AES-256-CBC with PKCS5 padding is supported
```bash
./main.out
# mode = aes-256-cbc | aes-256-cbc-d
# iv = initialization vector
```
### Encryption example
```bash
./main.out \
aes-256-cbc \
22332211aabb22aa889922aa99002200 \
2b7e151628aed2a6abf7158809cf4f3c2b7e151628aed2a6abf7158809cf4f3c \
in.txt \
in.txt.encrypted
# The same, but using openssl
openssl enc -aes-256-cbc \
-iv 22332211aabb22aa889922aa99002200 \
-K 2b7e151628aed2a6abf7158809cf4f3c2b7e151628aed2a6abf7158809cf4f3c \
-in in.txt \
-out in.txt.encrypted
```
### Decryption example
```bash
./main.out \
aes-256-cbc-d \
22332211aabb22aa889922aa99002200 \
2b7e151628aed2a6abf7158809cf4f3c2b7e151628aed2a6abf7158809cf4f3c \
in.txt.encrypted \
in.txt.decrypted
# The same, but using openssl
openssl enc -aes-256-cbc \
-d \
-iv 22332211aabb22aa889922aa99002200 \
-K 2b7e151628aed2a6abf7158809cf4f3c2b7e151628aed2a6abf7158809cf4f3c \
-in in.txt.encrypted \
-out in.txt.decrypted
```
## Using as library
```C
#include "./aes.c"
// First of all we need to initialize tables
init_tables();
// Block to encrypt
uint8_t block[BLOCK_SIZE] = {
0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff};
// Key. In this example it is 256 bits length
uint8_t cipher_key_256[AES_256_KEY_SIZE] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f};
// We have to perform expansion for the key according to standard
uint8_t expanded_key_256[AES_256_EXPANDED_KEY_SIZE];
fill_key_expansion(cipher_key_256, AES_256_KEY_SIZE, expanded_key_256);
// And thenn to encrypt the block
aes_encrypt_block(block, expanded_key_256, AES_256_KEY_SIZE);
// Now block contains encrypted data
```
## What can be improved
- Try to use x86/x64 operations for perfomance
- Chech that file is opened using buffered write - no need to perform fsync after each block