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| 1 | +//! The `KangarooTwelve` hash function defined [`here`]. |
| 2 | +//! |
| 3 | +//! [`here`]: https://eprint.iacr.org/2016/770.pdf |
| 4 | +
|
| 5 | +use crate::{bits_to_rate, keccakp::KeccakP, EncodedLen, Hasher, IntoXof, KeccakState, Xof}; |
| 6 | + |
| 7 | +fn encode_len(len: usize) -> EncodedLen { |
| 8 | + let len_view = (len as u64).to_be_bytes(); |
| 9 | + let offset = len_view.iter().position(|i| *i != 0).unwrap_or(8); |
| 10 | + let mut buffer = [0u8; 9]; |
| 11 | + buffer[..8].copy_from_slice(&len_view); |
| 12 | + buffer[8] = 8 - offset as u8; |
| 13 | + |
| 14 | + EncodedLen { offset, buffer } |
| 15 | +} |
| 16 | + |
| 17 | +/// The `KangarooTwelve` hash function defined [`here`]. |
| 18 | +/// |
| 19 | +/// # Usage |
| 20 | +/// |
| 21 | +/// ```toml |
| 22 | +/// [dependencies] |
| 23 | +/// tiny-keccak = { version = "2.0.0", features = ["k12"] } |
| 24 | +/// ``` |
| 25 | +/// |
| 26 | +/// [`here`]: https://eprint.iacr.org/2016/770.pdf |
| 27 | +#[derive(Clone)] |
| 28 | +pub struct KangarooTwelve<T> { |
| 29 | + state: KeccakState<KeccakP>, |
| 30 | + current_chunk: KeccakState<KeccakP>, |
| 31 | + custom_string: Option<T>, |
| 32 | + written: usize, |
| 33 | + chunks: usize, |
| 34 | +} |
| 35 | + |
| 36 | +impl<T> KangarooTwelve<T> { |
| 37 | + const MAX_CHUNK_SIZE: usize = 8192; |
| 38 | + |
| 39 | + /// Creates new [`KangarooTwelve`] hasher with a security level of 128 bits. |
| 40 | + /// |
| 41 | + /// [`KangarooTwelve`]: struct.KangarooTwelve.html |
| 42 | + pub fn new(custom_string: T) -> Self { |
| 43 | + let rate = bits_to_rate(128); |
| 44 | + KangarooTwelve { |
| 45 | + state: KeccakState::new(rate, 0), |
| 46 | + current_chunk: KeccakState::new(rate, 0x0b), |
| 47 | + custom_string: Some(custom_string), |
| 48 | + written: 0, |
| 49 | + chunks: 0, |
| 50 | + } |
| 51 | + } |
| 52 | +} |
| 53 | + |
| 54 | +impl<T: AsRef<[u8]>> Hasher for KangarooTwelve<T> { |
| 55 | + fn update(&mut self, input: &[u8]) { |
| 56 | + let mut to_absorb = input; |
| 57 | + if self.chunks == 0 { |
| 58 | + let todo = core::cmp::min(Self::MAX_CHUNK_SIZE - self.written, to_absorb.len()); |
| 59 | + self.state.update(&to_absorb[..todo]); |
| 60 | + self.written += todo; |
| 61 | + to_absorb = &to_absorb[todo..]; |
| 62 | + |
| 63 | + if to_absorb.len() > 0 && self.written == Self::MAX_CHUNK_SIZE { |
| 64 | + self.state.update(&[0x03, 0, 0, 0, 0, 0, 0, 0]); |
| 65 | + self.written = 0; |
| 66 | + self.chunks += 1; |
| 67 | + } |
| 68 | + } |
| 69 | + |
| 70 | + while to_absorb.len() > 0 { |
| 71 | + if self.written == Self::MAX_CHUNK_SIZE { |
| 72 | + let mut chunk_hash = [0u8; 32]; |
| 73 | + let current_chunk = self.current_chunk.clone(); |
| 74 | + self.current_chunk.reset(); |
| 75 | + current_chunk.finalize(&mut chunk_hash); |
| 76 | + self.state.update(&chunk_hash); |
| 77 | + self.written = 0; |
| 78 | + self.chunks += 1; |
| 79 | + } |
| 80 | + |
| 81 | + let todo = core::cmp::min(Self::MAX_CHUNK_SIZE - self.written, to_absorb.len()); |
| 82 | + self.current_chunk.update(&to_absorb[..todo]); |
| 83 | + self.written += todo; |
| 84 | + to_absorb = &to_absorb[todo..]; |
| 85 | + } |
| 86 | + } |
| 87 | + |
| 88 | + fn finalize(self, output: &mut [u8]) { |
| 89 | + let mut xof = self.into_xof(); |
| 90 | + xof.squeeze(output); |
| 91 | + } |
| 92 | +} |
| 93 | + |
| 94 | +/// The `KangarooTwelve` extendable-output function defined [`here`]. |
| 95 | +/// |
| 96 | +/// # Usage |
| 97 | +/// |
| 98 | +/// ```toml |
| 99 | +/// [dependencies] |
| 100 | +/// tiny-keccak = { version = "2.0.0", features = ["k12"] } |
| 101 | +/// ``` |
| 102 | +/// |
| 103 | +/// # Example |
| 104 | +/// |
| 105 | +/// ``` |
| 106 | +/// # use tiny_keccak::{KangarooTwelve, Xof, IntoXof, Hasher}; |
| 107 | +/// let input = b"hello world"; |
| 108 | +/// let mut output = [0u8; 64]; |
| 109 | +/// let mut hasher = KangarooTwelve::new(b""); |
| 110 | +/// hasher.update(input); |
| 111 | +/// let mut xof = hasher.into_xof(); |
| 112 | +/// xof.squeeze(&mut output[..32]); |
| 113 | +/// xof.squeeze(&mut output[32..]); |
| 114 | +/// ``` |
| 115 | +/// |
| 116 | +/// --- |
| 117 | +/// |
| 118 | +/// [`KangarooTwelveXof`] can be created only by using [`KangarooTwelve::IntoXof`] interface. |
| 119 | +/// |
| 120 | +/// [`here`]: https://eprint.iacr.org/2016/770.pdf |
| 121 | +/// [`KangarooTwelveXof`]: struct.KangarooTwelveXof.html |
| 122 | +/// [`KangarooTwelve::IntoXof`]: struct.KangarooTwelve.html#impl-IntoXof |
| 123 | +#[derive(Clone)] |
| 124 | +pub struct KangarooTwelveXof { |
| 125 | + state: KeccakState<KeccakP>, |
| 126 | +} |
| 127 | + |
| 128 | +impl<T: AsRef<[u8]>> IntoXof for KangarooTwelve<T> { |
| 129 | + type Xof = KangarooTwelveXof; |
| 130 | + |
| 131 | + fn into_xof(mut self) -> KangarooTwelveXof { |
| 132 | + let custom_string = self |
| 133 | + .custom_string |
| 134 | + .take() |
| 135 | + .expect("KangarooTwelve cannot be initialized without custom_string; qed"); |
| 136 | + let encoded_len = encode_len(custom_string.as_ref().len()); |
| 137 | + self.update(custom_string.as_ref()); |
| 138 | + self.update(encoded_len.value()); |
| 139 | + |
| 140 | + if self.chunks == 0 { |
| 141 | + self.state.delim = 0x07; |
| 142 | + } else { |
| 143 | + let encoded_chunks = encode_len(self.chunks); |
| 144 | + let mut tmp_chunk = [0u8; 32]; |
| 145 | + self.current_chunk.finalize(&mut tmp_chunk); |
| 146 | + self.state.update(&tmp_chunk); |
| 147 | + self.state.update(encoded_chunks.value()); |
| 148 | + self.state.update(&[0xff, 0xff]); |
| 149 | + self.state.delim = 0x06; |
| 150 | + } |
| 151 | + |
| 152 | + KangarooTwelveXof { state: self.state } |
| 153 | + } |
| 154 | +} |
| 155 | + |
| 156 | +impl Xof for KangarooTwelveXof { |
| 157 | + fn squeeze(&mut self, output: &mut [u8]) { |
| 158 | + self.state.squeeze(output); |
| 159 | + } |
| 160 | +} |
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