Crate rc5_block

RC5-RS Cipher Library

This crate provides a generic, parametric implementation of the RC5 block cipher, supporting variable word sizes (u16, u32, u64) and multiple modes of operation (ECB, CBC, CTR). It includes PKCS#7 padding helpers, IV/nonce generators, and convenient parsing of hex‐encoded parameters.

Features

• Variable word length: 16-bit, 32-bit, 64-bit.
• Various operation modes:
  • ECB
  • CBC
  • CTR
• Strict padding using PKCS#7 standard.
• Pseudo-random IV/nonce generation utitlities , see random_iv, random_nonce_and_counter.
• Hex‐string parsing for IVs and nonces.

Example

use rc5_block::{rc5_cipher, OperationMode};

// Build a 32‐bit word RC5 cipher with 12 rounds:
let cipher = rc5_cipher::<u32>(b"mykey", 12).unwrap();

let plaintext = b"Secret message";

// Encrypt in CBC mode with a random IV:
let iv = rc5_block::random_iv::<u32, 2>();
let ciphertext = cipher.encrypt(plaintext, OperationMode::CBC { iv }).unwrap();

// Decrypt using the same IV:
let recovered = cipher.decrypt(&ciphertext, OperationMode::CBC { iv }).unwrap();
assert_eq!(recovered, plaintext);

Utilities

This crate provide some extra utilities such as, pseudo-random iv and nonce generation and PKCS#7 padding function:

// generate a pseudo-random iv-block of block size [u32;2]
let iv = rc5_block::random_iv::<u32, 2>();

// generate a pseudo-random nonce and counter initialized to zero
// of block size [u32;2]
// Note: Higher part of this block conatins nonce and lower part
// contains counter with initial value set to zero.
let nonce_counter = rc5_block::random_nonce_and_counter::<u32, 2>();

Macros

bail

Helper macro to bail out early with a Reason error if any condition is true.

Structs

Cipher

Cipher

RC5ControlBlock

RC5 control block

Version

RC5 version identifier

Enums

OperationMode

Modes of operation for a block cipher.

Reason

Errors returned by the Cipher as reasons during cipher operations.

Traits

BlockCipher

A core trait that any block-cipher must implement to work with Cipher.

Word

A core trait to define a word in N-sized blocks of a block cipher. This word must support arithmatic and binary operations required for cryptographic functions.

Functions

pkcs7

Apply or remove PKCS#7 padding on the given buffer in place.

random_iv

Generate a pseudo‑random IV (Initialization-Vector) of [W; N].

random_nonce_and_counter

Generate a pseudo‑random block of N words where the last word is zero (suitable for use as a CTR‐mode nonce + counter seed).

rc5_cipher

Construct a new RC5 cipher from a raw key and round count.

Type Aliases

RC5Cipher