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@@ -0,0 +1,93 @@
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+//
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+// ChaCha20.swift
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+// CryptoSwift
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+//
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+// Created by Marcin Krzyzanowski on 25/08/14.
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+// Copyright (c) 2014 Marcin Krzyzanowski. All rights reserved.
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+//
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+
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+import Foundation
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+
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+public class ChaCha20 {
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+ let keySize = 32
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+ let nonceSize = 8
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+ let stateSize = 16
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+ let blockSize = 16 * 4
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+
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+ public init() {
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+ }
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+
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+ public func wordToByte(input:[UInt32] /* 64 */) -> [Byte]? /* 16 */ {
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+ if (input.count != stateSize) {
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+ return nil;
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+ }
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+
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+ var x:[UInt32] = [UInt32]()
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+ for val in input[0...15] {
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+ x.append(val)
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+ }
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+
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+ for (var i = 8; i > 0; i -= 2) {
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+ quarterround(&x[0], &x[4], &x[8], &x[12])
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+ quarterround(&x[1], &x[5], &x[9], &x[13])
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+ quarterround(&x[2], &x[6], &x[10], &x[14])
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+ quarterround(&x[3], &x[7], &x[11], &x[15])
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+ quarterround(&x[0], &x[5], &x[10], &x[15])
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+ quarterround(&x[1], &x[6], &x[11], &x[12])
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+ quarterround(&x[2], &x[7], &x[8], &x[13])
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+ quarterround(&x[3], &x[4], &x[9], &x[14])
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+ }
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+
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+ for (idx,val) in enumerate(input[0...15]) {
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+ x[idx] = plus(x[idx],val)
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+ }
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+
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+ var output:[Byte] = [Byte](count: 64, repeatedValue: 0)
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+ for (i,xval) in enumerate(x[0...15]) {
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+ let bytes = x[i].bytes()
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+ let start = (i * 4)
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+ for o in start..<(start + 4) {
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+ output[o] = bytes[o - start]
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+ }
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+ }
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+
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+ return output;
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+ }
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+
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+ private func UInt32To8Little(p:UInt32, _ v:UInt32) -> UInt8 {
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+ var tmp1 = (v >> 0) & 0xff | (v >> 8) & 0xff
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+ var tmp2 = (v >> 16) & 0xff | (v >> 24) & 0xff
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+ return UInt8(tmp1 | tmp2)
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+ }
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+
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+ // rotate left
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+ private func rotate(v:UInt32, _ c:UInt32) -> UInt32 {
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+ return ((v << c) & 0xFFFFFFFF) | (v >> (32 - c))
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+ }
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+
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+ private func u32v(x:UInt32) -> UInt32 {
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+ return x & 0xFFFFFFFF
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+ }
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+
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+ private func plusone(v:UInt32) -> UInt32 {
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+ return plus(v, 1)
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+ }
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+
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+ private func plus(v:UInt32, _ w:UInt32) -> UInt32 {
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+ return v &+ w
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+ }
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+
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+ private func quarterround(inout a:UInt32, inout _ b:UInt32, inout _ c:UInt32, inout _ d:UInt32) {
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+ a = plus(a,b);
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+ d = rotate((d ^ a), 16)
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+
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+ c = plus(c,d);
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+ b = rotate((b ^ c), 12);
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+
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+ a = plus(a,b);
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+ d = rotate((d ^ a), 8);
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+
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+ c = plus(c,d);
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+ b = rotate((b ^ c), 7);
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+ }
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+}
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Marcin Krzyżanowski