gx-twofish64/docs/README.en.md

A library for encrypting and decrypting data using the Twofish algorithm and Base64 encoding. Based on the Genexus implementation (Encrypt64 and Decrypt64).

# gx-twofish64

Encryption and decryption compatible with **GeneXus**, using the **Twofish** algorithm and **Base64** encoding.

This package replicates the logic of `Encrypt64` and `Decrypt64` used in GeneXus, allowing interoperability with systems developed on that platform.

## Installation

```bash
npm install gx-twofish64
```

# Usage

```ts
import { encrypt64, decrypt64 } from 'gx-twofish64'

const text = 'Hola mundo'
const hexKey = '21972247ba570855360dbf70c8fa2e0e' // Valid hexadecimal key (32 chars for 128 bits)

const encrypted = encrypt64(text, hexKey)
console.log('Encrypted:', encrypted)

const decrypted = decrypt64(encrypted, hexKey)
console.log('Decrypted:', decrypted)
```

# API

### `encrypt64(text: string, hexKey: string): string`

-   `text`: Plain text to encrypt.
-   `hexKey`: Hexadecimal key. Must be 16 bytes (32 hex characters).
-   Returns: Encrypted text as Base64.

### `decrypt64(base64Text: string, hexKey: string): string`

-   `base64Text`: Encrypted text in Base64.
-   `hexKey`: Hexadecimal key (same one used for encryption).
-   Returns: Decrypted plain text.

# Technical details

-   Algorithm: Twofish in ECB mode.
-   Block size: 16 bytes.
-   Padding: Space padding (`0x20`), same as used in GeneXus.
-   Encoding: Base64.

# Compatibility

✔ Compatible with values generated by GeneXus `Encrypt64()` and `Decrypt64()` functions.