KangarooTwelve

Background

A pure-Julia implementation of the KangarooTwelve hashing scheme, so named because it consists of 12 rounds of Keccak (TurboSHAKE128) with kangaroo hopping, allowing for parallel tree-ish hashing termed "leaves stapled to a pole".

This scheme presents a particularly good balance of:

  • Simplicity (Keccak + sponge + hopping)
  • Security (128-bit)
  • Speed (up to ~2bytes/cycle)

It is currently an IETF draft.

Usage

KangarooTwelve.k12 — Function
k12(data::Union{IO, String, AbstractVector{<:Unsigned}},
    customisation::Union{String, AbstractVector{<:Unsigned}};
    thread::Bool=true) -> UInt128

Hash data with the KangarooTwelve scheme and a customisation value, using multithreading when thread is true.

This scheme presents a good balance of Simplicity, Security, and Speed.

Extended help

The KangarooTwelve hashing scheme works by splitting the input data into $n$ 8192-byte blocks ($S₀$, $S₁$, …, $Sₙ₋₁$) which are individually hashed with TurboSHAKE128 to produce 32-byte "chaining values" (CVs), which are put together and absorbed to produce the final state.

               ╭────╮ ╭────╮   ╭────╮ ╭────╮
               │ S₁ │ │ S₂ │   │Sₙ₋₂│ │Sₙ₋₁│
               ╰─┬──╯ ╰─┬──╯   ╰─┬──╯ ╰─┬──╯
                 │110   │110     │110   │110
                 ▼      ▼        ▼      ▼
╭────────╮110⁶²╭─┴──╮ ╭─┴──╮   ╭─┴──╮ ╭─┴──╮
│   S₀   ├─────┤ CV ├─┤ CV ├╴╍╶┤ CV ├─┤ CV ├─(n-1)(FFFF)(01)──▶─┤HASH│
╰────────╯     ╰────╯ ╰────╯   ╰────╯ ╰────╯

This scheme has been described as "leaves on a vine". The hashing of blocks $S₁$ to $Sₙ₋₁$ is embarassingly parallel, and can be accelerated with both SIMD and multithreading.

source