noodling with devices & generators in swift

dev_random.swift

#!/usr/bin/env swift

import Foundation

class Dev {
  let desc: Int32
  var data = NSMutableData(length: 1)!
  init(_ name: String) {
    desc = Darwin.open("/dev/\(name)", O_RDONLY)
  }
  deinit {
    Darwin.close(desc)
  }
  func read() -> UInt8? {
    var mPtr = UnsafeMutablePointer<UInt8>(data.bytes)
    if Darwin.read(desc, mPtr, 1) > 0 {
      return mPtr.memory
    }
    return nil
  }
}

let devRandom = Dev("random")
let randomBytes = lazy(GeneratorOf(devRandom.read))

for byte in randomBytes {
  print(String(format: "%02X", byte))
  if byte == 0 {
    println()
    break
  }
}

func unZip2<T,U>(s: [(T, U)]) -> ([T], [U]) {
  return (s.map{ $0.0 }, s.map{ $0.1 })
}

let text = "I am the very model of a modern major general"

// XOR is strong digital defense
let superSecureCipher = { (m: Byte, k: Byte) -> (Byte, Byte) in (m ^ k, k) }

let (encrypted, key) = unZip2(map(Zip2(text.utf8, randomBytes), superSecureCipher))

println("Encrypted: " + "".join(encrypted.map{ String(format: "%02X", $0)}))
println("One-time pad: " + "".join(key.map{ String(format: "%02X", $0)}))

let decrypted = unZip2(map(Zip2(encrypted, key), superSecureCipher)).0

println("Decrypted: " + "".join(decrypted.map{ String(UnicodeScalar($0)) }))