39 lines
1.2 KiB
Kotlin
39 lines
1.2 KiB
Kotlin
package com.infendro.kdf
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import com.infendro.bytes.bytearray.xorInto
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import com.infendro.bytes.int.copyInto
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import com.infendro.hash.HashFunction
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import com.infendro.kdf.util.ceilDiv
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import com.infendro.mac.HMAC
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class PBKDF2(
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override val bytes: Int,
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private val iterations: Int,
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function: HashFunction,
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) : KDF {
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init {
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require(bytes > 0)
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require(iterations > 0)
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}
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private val hmac = HMAC(function)
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override fun hashInto(value: ByteArray, salt: ByteArray, destination: ByteArray, destinationOffset: Int) {
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for (iteration in 1..bytes.ceilDiv(hmac.bytes)) {
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val offset = (iteration - 1) * hmac.bytes
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val block = minOf(bytes - offset, hmac.bytes)
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val s = ByteArray(salt.size + 4)
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salt.copyInto(s)
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iteration.copyInto(s, salt.size)
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val buffer = hmac.hash(value, s)
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buffer.copyInto(destination, destinationOffset + offset, endIndex = block)
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repeat(iterations - 1) {
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hmac.hashInto(value, buffer, buffer)
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buffer.xorInto(destination, destinationOffset + offset, endIndex = block)
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}
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}
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}
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}
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