Open-source multiplayer game server compatible with the RuneScape client
https://www.openrs2.org/
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58 lines
1.6 KiB
58 lines
1.6 KiB
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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inline class XteaKey(internal val k: IntArray) {
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val isZero: Boolean
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get() = k[0] == 0 && k[1] == 0 && k[2] == 0 && k[3] == 0
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companion object {
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val ZERO = XteaKey(IntArray(4))
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}
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}
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fun ByteBuf.xteaEncrypt(index: Int, length: Int, key: XteaKey) {
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require(key.k.size == 4)
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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 + key.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 + key.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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fun ByteBuf.xteaDecrypt(index: Int, length: Int, key: XteaKey) {
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require(key.k.size == 4)
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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 + key.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 + key.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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