Struct AutokeyCipher 

pub struct AutokeyCipher { /* private fields */ }

Implementations

impl AutokeyCipher

pub fn new(key: &str) -> Self

Trait Implementations

impl Block for AutokeyCipher

fn encrypt(&self, dst: &mut [u8], src: &[u8]) -> usize

Encrypts plaintext using the Autokey cipher.

The autokey cipher uses the key for the first characters, then appends the plaintext itself to form an extended key. This creates a keystream that is as long as the message without repeating the original key.

Algorithm

For each character at position i:

• If i < key.len(): use key[i]
• Otherwise: use plaintext[i - key.len()]

Then apply standard Vigenère encryption: C[i] = (P[i] + K[i]) mod 26

Arguments

• dst - Destination buffer where encrypted bytes will be written
• src - Source plaintext bytes (expected to be uppercase A-Z)

Returns

The length of the destination buffer

Examples

let cipher = AutokeyCipher::new("KEY");
let pt = b"HELLO";
let mut ct = vec![0u8; pt.len()];
cipher.encrypt(&mut ct, pt);
assert_eq!(&ct, b"RIJSS");

fn decrypt(&self, dst: &mut [u8], src: &[u8]) -> usize

Decrypts ciphertext using the Autokey cipher.

Reverses the autokey encryption process by using the key for the first characters, then using the previously decrypted plaintext to continue the keystream.

Algorithm

For each character at position i:

• If i < key.len(): use key[i]
• Otherwise: use decrypted_plaintext[i - key.len()]
• Decrypt: P[i] = (C[i] - K[i]) mod 26 (or equivalently: (C[i] + (26 - K[i])) mod 26)

Each character must be decrypted in order since the plaintext is needed for the next key.

Arguments

• dst - Destination buffer where decrypted bytes will be written
• src - Source ciphertext bytes (expected to be uppercase A-Z)

Returns

The number of bytes written to the destination buffer

Examples

let cipher = AutokeyCipher::new("KEY");
let ct = b"RIJSS";
let mut pt = vec![0u8; ct.len()];
cipher.decrypt(&mut pt, ct);
assert_eq!(&pt, b"HELLO");

fn block_size(&self) -> usize

impl Debug for AutokeyCipher

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.