CryptoSwift/Sources/CryptoSwift/Utils.swift

//
//  Utils.swift
//  CryptoSwift
//
//  Created by Marcin Krzyzanowski on 26/08/14.
//  Copyright (c) 2014 Marcin Krzyzanowski. All rights reserved.
//

func rotateLeft(_ value:UInt8, by:UInt8) -> UInt8 {
    return ((value << by) & 0xFF) | (value >> (8 - by))
}

func rotateLeft(_ value:UInt16, by:UInt16) -> UInt16 {
    return ((value << by) & 0xFFFF) | (value >> (16 - by))
}

func rotateLeft(_ value:UInt32, by:UInt32) -> UInt32 {
    return ((value << by) & 0xFFFFFFFF) | (value >> (32 - by))
}

func rotateLeft(_ value:UInt64, by:UInt64) -> UInt64 {
    return (value << by) | (value >> (64 - by))
}

func rotateRight(_ value:UInt16, by:UInt16) -> UInt16 {
    return (value >> by) | (value << (16 - by))
}

func rotateRight(_ value:UInt32, by:UInt32) -> UInt32 {
    return (value >> by) | (value << (32 - by))
}

func rotateRight(_ value:UInt64, by:UInt64) -> UInt64 {
    return ((value >> by) | (value << (64 - by)))
}

func reversed(_ uint8 : UInt8) -> UInt8 {
    var v = uint8
    v = (v & 0xF0) >> 4 | (v & 0x0F) << 4
    v = (v & 0xCC) >> 2 | (v & 0x33) << 2
    v = (v & 0xAA) >> 1 | (v & 0x55) << 1
    return v
}

func reversed(_ uint32 : UInt32) -> UInt32 {
    var v = uint32
    v = ((v >> 1) & 0x55555555) | ((v & 0x55555555) << 1)
    v = ((v >> 2) & 0x33333333) | ((v & 0x33333333) << 2)
    v = ((v >> 4) & 0x0f0f0f0f) | ((v & 0x0f0f0f0f) << 4)
    v = ((v >> 8) & 0x00ff00ff) | ((v & 0x00ff00ff) << 8)
    v = ((v >> 16) & 0xffff) | ((v & 0xffff) << 16)
    return v
}

func xor(_ a: Array<UInt8>, _ b:Array<UInt8>) -> Array<UInt8> {
    var xored = Array<UInt8>(repeating: 0, count: min(a.count, b.count))
    for i in 0..<xored.count {
        xored[i] = a[i] ^ b[i]
    }
    return xored
}

/**
 ISO/IEC 9797-1 Padding method 2.
 Add a single bit with value 1 to the end of the data.
 If necessary add bits with value 0 to the end of the data until the padded data is a multiple of blockSize.
 - parameters:
 - blockSize: Padding size in bytes.
 - allowance: Excluded trailing number of bytes.
 */
func bitPadding(to data: Array<UInt8>, blockSize: Int, allowance: Int = 0) -> Array<UInt8> {
    var tmp = data

    // Step 1. Append Padding Bits
    tmp.append(0x80) // append one bit (UInt8 with one bit) to message

    // append "0" bit until message length in bits ≡ 448 (mod 512)
    var msgLength = tmp.count
    var counter = 0

    while msgLength % blockSize != (blockSize - allowance) {
        counter += 1
        msgLength += 1
    }

    tmp += Array<UInt8>(repeating: 0, count: counter)
    return tmp
}