chacha20-crypt ( data key nonce counter -- result )
ChaCha20 stream cipher

Next:

chacha20-crypt-bytes ( data key-bytes nonce-bytes counter -- result )

Vocabulary
crypto.chacha20

Inputs

data	a byte-array
key	8 u32 values (256 bits)
nonce	3 u32 values (96 bits)
counter	starting block counter

Outputs

result

a byte-array

Word description
Encrypts or decrypts data using ChaCha20. XOR is symmetric, so the same function works for both encryption and decryption.

Examples

USING: byte-arrays crypto.chacha20 ; "Hello" >byte-array 8 0 <array> 3 0 <array> 1 chacha20-crypt 8 0 <array> 3 0 <array> 1 chacha20-crypt >string
! => "Hello"

Definition

USING: crypto.chacha20.private grouping math sequences ;

IN: crypto.chacha20

:: chacha20-crypt ( data key nonce counter -- result )
    data 64 group [| block i |
        key nonce counter i + chacha20-block-state
        state>keystream block length head block [ bitxor ] 2map
    ] map-index concat ;