WEP 64 Bit Key Generation

wep_64.swift

// Created by: Jess Bodzo
// The code below is a simple WEP key generator based off a given passphrase

import UIKit
import Foundation

var psk = "password"
let m = UInt(1 << 32)
let c = UInt(0x269ec3)
let a = UInt(0x343fd)

func wep_encrypt_64(passphrase: String) -> [String] {
    /** Convert the passphrase into a unicode value representation **/
    var arr: [UInt] = [0,0,0,0]
    let unicode_scalars = passphrase.utf16
    let unicode_byte_values: [UInt] = unicode_scalars.map({UInt($0 as UInt16)})
    /** Generate array values based off cycling through the array and performing XORs **/
    for (var i = 0; i < passphrase.characters.count; i++) {
        let arr_index = i & 3   // Cycles through indices of arr {0,1,2,3,0,1,...}
        arr[arr_index] ^= unicode_byte_values[unicode_byte_values.startIndex.advancedBy(i)]
    }
    
    // Linearly shift the values by 8 times the index position
    var p = 0
    let shifted_arr = arr.map({UInt($0 << UInt(8*p++))})
    
    // Reduce the linear shift result by successively OR'ing with each index
    let x = shifted_arr.reduce(0) { (reduction, operand) -> UInt in reduction | operand }
    
    // Generate each part of the key using the recursive relationship defined for WEP
    let i_keys = linear_congruential_gen(x, 20)
    
    // Final resulting keys generated by combining the key parts
    var keys: [String] = []
    // The loop below reduces each cluster of 4 unsigned integers into their hexadecimal representation in a String
    for (var j = 0; j < 20; j+=5) {
        keys.append(i_keys[j...j+4].reduce(String("")) { (var key, piece) -> String in
                        return key + String(format: "%2X", piece)
                    })
    }
    return keys
}

func linear_congruential_gen(var x: UInt, _ iter: Int) -> [UInt] {
    var i_keys: [UInt] = []
    for (var i = 0; i < iter; i++) {
        x = (a * x + c) % m
        i_keys.append((x >> 16) & 0xff)
    }
    return i_keys
}

var psk_64 = wep_encrypt_64(psk)