124 lines
3.5 KiB
Kotlin
124 lines
3.5 KiB
Kotlin
package com.infendro.hash.keccak
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import com.infendro.bytearray.ByteOrder.LITTLE_ENDIAN
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import com.infendro.bytearray.toUByteArray
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import com.infendro.bytearray.toULongArray
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import com.infendro.hash.HashFunction
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import kotlin.math.min
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abstract class Keccak(
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override val bytes: Int,
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private val rate: Int,
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private val domain: UByte,
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) : HashFunction {
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override val block: Int
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get() = rate
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private val rc = ulongArrayOf(
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0x0000000000000001UL, 0x0000000000008082UL, 0x800000000000808aUL, 0x8000000080008000UL,
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0x000000000000808bUL, 0x0000000080000001UL, 0x8000000080008081UL, 0x8000000000008009UL,
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0x000000000000008aUL, 0x0000000000000088UL, 0x0000000080008009UL, 0x000000008000000aUL,
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0x000000008000808bUL, 0x800000000000008bUL, 0x8000000000008089UL, 0x8000000000008003UL,
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0x8000000000008002UL, 0x8000000000000080UL, 0x000000000000800aUL, 0x800000008000000aUL,
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0x8000000080008081UL, 0x8000000000008080UL, 0x0000000080000001UL, 0x8000000080008008UL,
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)
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private val rotation = arrayOf(
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intArrayOf(0, 36, 3, 41, 18),
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intArrayOf(1, 44, 10, 45, 2),
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intArrayOf(62, 6, 43, 15, 61),
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intArrayOf(28, 55, 25, 21, 56),
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intArrayOf(27, 20, 39, 8, 14),
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)
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override fun hash(
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value: UByteArray,
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): UByteArray {
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val state = ULongArray(25)
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val blocks = pad(value)
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.chunked(rate) { it.toUByteArray() }
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for (block in blocks) {
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absorb(state, block)
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}
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return squeeze(state)
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}
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private fun pad(
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value: UByteArray,
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): UByteArray {
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return buildList {
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addAll(value)
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add(domain)
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while ((size % rate) != (rate - 1)) {
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add(0x00U)
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}
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add(0x80U)
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}.toUByteArray()
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}
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private fun absorb(
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state: ULongArray,
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block: UByteArray,
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) {
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val numbers = block.toULongArray(LITTLE_ENDIAN)
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for ((i, number) in numbers.withIndex()) {
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state[i] = state[i] xor number
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}
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permute(state)
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}
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private fun permute(
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a: ULongArray,
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) {
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val b = ULongArray(25)
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val c = ULongArray(5)
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val d = ULongArray(5)
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repeat(24) { round ->
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// θ
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for (x in 0..4) {
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c[x] = a[x] xor a[x + 5] xor a[x + 10] xor a[x + 15] xor a[x + 20]
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}
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for (x in 0..4) {
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d[x] = c[(x + 4) % 5] xor c[(x + 1) % 5].rotateLeft(1)
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}
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for (x in 0..4) for (y in 0..4) {
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a[x + 5 * y] = a[x + 5 * y] xor d[x]
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}
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// ρ and π
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for (x in 0..4) for (y in 0..4) {
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b[y + 5 * ((2 * x + 3 * y) % 5)] = a[x + 5 * y].rotateLeft(rotation[x][y])
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}
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// χ
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for (x in 0..4) for (y in 0..4) {
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a[x + 5 * y] = b[x + 5 * y] xor ((b[((x + 1) % 5) + 5 * y].inv()) and b[((x + 2) % 5) + 5 * y])
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}
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// ι
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a[0] = a[0] xor rc[round]
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}
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}
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private fun squeeze(
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state: ULongArray,
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): UByteArray {
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return buildList {
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var i = 0
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while (size < bytes) {
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if (i == rate / 8) {
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permute(state)
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i = 0
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}
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addAll(
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state[i++].toUByteArray(LITTLE_ENDIAN)
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.sliceArray(0..<min(bytes - size, 8))
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)
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}
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}.toUByteArray()
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}
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}
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