https://github.com/mauricelambert/fastrc4

Optimized implementation of RC4 (Rivest Cipher 4, ARCFOUR) in ASM (x64) for Linux and Windows.
https://github.com/mauricelambert/fastrc4

arc4 asm cipher encrypt linux optimization poc rc4 windows

Last synced: about 10 hours ago
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Optimized implementation of RC4 (Rivest Cipher 4, ARCFOUR) in ASM (x64) for Linux and Windows.

• Host: GitHub
• URL: https://github.com/mauricelambert/fastrc4
• Owner: mauricelambert
• License: gpl-3.0
• Created: 2023-03-11T22:49:13.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2024-06-18T10:44:40.000Z (5 months ago)
• Last Synced: 2024-06-18T12:08:58.075Z (5 months ago)
• Topics: arc4, asm, cipher, encrypt, linux, optimization, poc, rc4, windows
• Language: Assembly
• Homepage:
• Size: 61.5 KB
• Stars: 3
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

        
# FastRC4 - LibARC4

> **This RC4 implementation is not secure, it is a POC for an optimized RC4 implementation in ASM. You should never use this implementation for TLS, WEP, ... or other old protocols using RC4. You should never use it to encrypt secrets or very large file.**

>> The RC4 algorithm validity is checked with lddgo.net API to be sure is correct.

## Description

This repository implements RC4 encryption with IV, written in ASM with few optimizations.

## Requirements

 - To use the shared library you don't need any requirements.

 - To use the python interface you need Python3 and the standard library.

## Compilation

### Linux

```bash

nasm -felf64 ARC4.asm

ld -shared ARC4.o -o librc4.so

strip librc4.so

```

### Windows

```bash

nasm -fwin64 rc4_win.asm

gcc -shared rc4_win.obj -o librc4.dll

strip librc4.dll

```

## Usages

### Exported functions

```c

char *get_iv();

void *encrypt(char *key, char *data, unsigned long long length);

void *decrypt(char *key, char iv[256], char *data, unsigned long long length);

void *generate_iv();

void *xor_key_iv();

void *generate_key(char *key);

void *arc4_null_byte(char *data);

void *arc4(char *data, unsigned long long length);

void *reset_key();

void *set_iv(char *iv);

```

```

arc4_null_byte([IN/OUT] char *data) -> NULL

arc4([IN/OUT] char *data, [IN] unsigned long long length) -> NULL

generate_iv() -> NULL

xor_key_iv() -> NULL

generate_key(char *key) -> NULL

reset_key() -> NULL

get_iv() -> char[256] // null byte terminate string

set_iv([IN] char iv[256]) -> NULL

encrypt([IN] char *key, [IN/OUT] char *data, [IN] unsigned long long length) -> NULL  // if length is 0 call arc4_null_byte

decrypt([IN] char *key, [IN] char iv[256], [IN/OUT] char *data, [IN] unsigned long long length) -> NULL // there is no way to decrypt string terminating by null byte because encrypted data can contains null byte

```

### Python interface

```python

from librc4 import RC4

rc4 = RC4(b'my key')

cipher = rc4.encrypt(b'my data')

secret = rc4.decrypt(cipher)

```

## Licence

Licensed under the [GPL, version 3](https://www.gnu.org/licenses/).