Infendro/prng.kt
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implement optimizations

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Infendro
2026-01-30 13:41:43 +01:00
parent 7144c21074
commit 0f890c923c
10 changed files with 99 additions and 168 deletions
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5
src/commonMain/kotlin/com/infendro/random/CSPRNG.kt Normal file
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package com.infendro.random
abstract class CSPRNG : PRNG() {
abstract fun reseed(entropy: ByteArray)
}

16
src/commonMain/kotlin/com/infendro/random/PRNG.kt Normal file
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package com.infendro.random
import kotlin.random.Random
abstract class PRNG : Random() {
abstract fun seed(seed: ByteArray)
protected abstract fun generate(): Int
override fun nextBits(bitCount: Int): Int {
require(bitCount in 0..32)
if (bitCount == 0) return 0
return generate() ushr (32 - bitCount)
}
}

16
src/commonMain/kotlin/com/infendro/random/csprng/CSPRNG.kt
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package com.infendro.random.csprng
import com.infendro.hash.HashFunction
import com.infendro.random.prng.PRNG
abstract class CSPRNG : PRNG() {
abstract fun reseed(
entropy: UByteArray,
)
companion object {
fun HMAC(
function: HashFunction,
) = com.infendro.random.csprng.HMAC(function)
}
}

37
src/commonMain/kotlin/com/infendro/random/csprng/HMAC-DRBG.kt Normal file
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package com.infendro.random.csprng
import com.infendro.bytes.bytearray.toInt
import com.infendro.hash.HashFunction
import com.infendro.mac.HMAC
import com.infendro.random.CSPRNG
import kotlin.properties.Delegates.notNull
class `HMAC-DRBG` internal constructor(
private val function: HashFunction,
) : CSPRNG() {
private val hmac = HMAC(function)
private var k: ByteArray by notNull()
private var v: ByteArray by notNull()
override fun seed(seed: ByteArray) {
k = ByteArray(function.bytes) { 0x00 }
v = ByteArray(function.bytes) { 0x01 }
reseed(seed)
}
override fun reseed(entropy: ByteArray) {
k = hmac.hash(k, v + byteArrayOf(0x00) + entropy)
v = hmac.hash(k, v)
k = hmac.hash(k, v + byteArrayOf(0x01) + entropy)
v = hmac.hash(k, v)
}
override fun generate(): Int {
v = hmac.hash(k, v)
val result = v.toInt()
k = hmac.hash(k, v + byteArrayOf(0x00))
v = hmac.hash(k, v)
return result
}
}

47
src/commonMain/kotlin/com/infendro/random/csprng/HMAC.kt
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@@ -1,47 +0,0 @@
package com.infendro.random.csprng
import com.infendro.hash.HashFunction
import kotlin.math.min
import kotlin.properties.Delegates.notNull
class HMAC internal constructor(
private val function: HashFunction,
) : CSPRNG() {
private val hmac = com.infendro.mac.HMAC(function)
private var k: UByteArray by notNull()
private var v: UByteArray by notNull()
override fun seed(
seed: UByteArray,
) {
k = UByteArray(function.bytes) { 0x00U }
v = UByteArray(function.bytes) { 0x01U }
reseed(seed)
}
override fun reseed(
entropy: UByteArray,
) {
k = hmac.hash(k, v + ubyteArrayOf(0x00U) + entropy)
v = hmac.hash(k, v)
k = hmac.hash(k, v + ubyteArrayOf(0x01U) + entropy)
v = hmac.hash(k, v)
}
override fun generate(
count: Int,
): UByteArray {
val bytes = buildList {
while (size < count) {
v = hmac.hash(k, v)
addAll(v.take(min(count - size, function.bytes)))
}
}.toUByteArray()
k = hmac.hash(k, v + ubyteArrayOf(0x00U))
v = hmac.hash(k, v)
return bytes
}
}

36
src/commonMain/kotlin/com/infendro/random/prng/LCG.kt
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@@ -1,33 +1,23 @@
package com.infendro.random.prng
import com.infendro.bytearray.padStart
import com.infendro.bytearray.toUByteArray
import com.infendro.bytearray.toULong
import kotlin.math.min
import kotlin.properties.Delegates
import com.infendro.bytes.bytearray.toLong
import com.infendro.hash.sha2.`SHA-256`
import com.infendro.random.PRNG
import kotlin.properties.Delegates.notNull
class LCG internal constructor() : PRNG() {
private val a: ULong = 25214903917UL
private val c: ULong = 11UL
private val m: ULong = 1UL shl 48
private val a: Long = 25214903917L
private val c: Long = 11L
private val mask: Long = (1L shl 48) - 1
private var x: ULong by Delegates.notNull()
private var x: Long by notNull()
override fun seed(
seed: UByteArray,
) {
val s = seed.padStart(8, 0x00U).takeLast(8).toUByteArray()
x = s.toULong() % m
override fun seed(seed: ByteArray) {
x = `SHA-256`.hash(seed).toLong() and mask
}
override fun generate(
count: Int,
): UByteArray {
return buildList {
while (size < count) {
x = (a * x + c) % m
addAll(x.toUByteArray().takeLast(min(count - size, 6)))
}
}.toUByteArray()
override fun generate(): Int {
x = (a * x + c) and mask
return (x ushr 16).toInt()
}
}

44
src/commonMain/kotlin/com/infendro/random/prng/PRNG.kt
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@@ -1,44 +0,0 @@
package com.infendro.random.prng
import com.infendro.bytearray.toInt
import kotlin.random.Random
abstract class PRNG : Random() {
abstract fun seed(
seed: UByteArray,
)
abstract fun generate(
count: Int,
): UByteArray
override fun nextBits(
bitCount: Int,
): Int {
require(bitCount in 0..32)
if (bitCount == 0) return 0
return generate(4).toInt() ushr (32 - bitCount)
}
override fun nextBytes(
array: ByteArray,
fromIndex: Int,
toIndex: Int,
): ByteArray {
require(fromIndex in 0..array.size && toIndex in 0..array.size)
require(fromIndex <= toIndex)
val size = toIndex - fromIndex
val bytes = generate(size).asByteArray()
for (i in 0..<size) {
array[i + fromIndex] = bytes[i]
}
return array
}
companion object {
fun LCG() = com.infendro.random.prng.LCG()
}
}