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package dev.openrs2.crypto
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import io.netty.buffer.ByteBuf
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private const val GOLDEN_RATIO = 0x9e3779b9.toInt()
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private const val ROUNDS = 32
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private const val BLOCK_SIZE = 8
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private const val BLOCK_SIZE_MASK = BLOCK_SIZE - 1
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public class XteaKey(
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public val k0: Int,
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public val k1: Int,
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public val k2: Int,
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public val k3: Int
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) {
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public val isZero: Boolean
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get() = k0 == 0 && k1 == 0 && k2 == 0 && k3 == 0
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public fun toIntArray(): IntArray {
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return intArrayOf(k0, k1, k2, k3)
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}
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public fun toHex(): String {
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return Integer.toUnsignedString(k0, 16).padStart(8, '0') +
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Integer.toUnsignedString(k1, 16).padStart(8, '0') +
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Integer.toUnsignedString(k2, 16).padStart(8, '0') +
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Integer.toUnsignedString(k3, 16).padStart(8, '0')
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}
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override fun toString(): String {
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return toHex()
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}
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public companion object {
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public val ZERO: XteaKey = XteaKey(0, 0, 0, 0)
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public fun fromIntArray(a: IntArray): XteaKey {
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require(a.size == 4)
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return XteaKey(a[0], a[1], a[2], a[3])
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}
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public fun fromHex(s: String): XteaKey {
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require(s.length == 32)
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val k0 = Integer.parseUnsignedInt(s, 0, 8, 16)
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val k1 = Integer.parseUnsignedInt(s, 8, 16, 16)
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val k2 = Integer.parseUnsignedInt(s, 16, 24, 16)
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val k3 = Integer.parseUnsignedInt(s, 24, 32, 16)
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return XteaKey(k0, k1, k2, k3)
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}
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}
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}
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public fun ByteBuf.xteaEncrypt(index: Int, length: Int, key: XteaKey) {
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val k = key.toIntArray()
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val end = index + (length and BLOCK_SIZE_MASK.inv())
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for (i in index until end step BLOCK_SIZE) {
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var sum = 0
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var v0 = getInt(i)
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var v1 = getInt(i + 4)
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for (j in 0 until ROUNDS) {
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v0 += (((v1 shl 4) xor (v1 ushr 5)) + v1) xor (sum + k[sum and 3])
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sum += GOLDEN_RATIO
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v1 += (((v0 shl 4) xor (v0 ushr 5)) + v0) xor (sum + k[(sum ushr 11) and 3])
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}
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setInt(i, v0)
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setInt(i + 4, v1)
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}
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}
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public fun ByteBuf.xteaDecrypt(index: Int, length: Int, key: XteaKey) {
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val k = key.toIntArray()
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val end = index + (length and BLOCK_SIZE_MASK.inv())
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for (i in index until end step BLOCK_SIZE) {
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@Suppress("INTEGER_OVERFLOW")
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var sum = GOLDEN_RATIO * ROUNDS
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var v0 = getInt(i)
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var v1 = getInt(i + 4)
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for (j in 0 until ROUNDS) {
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v1 -= (((v0 shl 4) xor (v0 ushr 5)) + v0) xor (sum + k[(sum ushr 11) and 3])
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sum -= GOLDEN_RATIO
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v0 -= (((v1 shl 4) xor (v1 ushr 5)) + v1) xor (sum + k[sum and 3])
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}
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setInt(i, v0)
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setInt(i + 4, v1)
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}
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}
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