iosdevzone/idzswiftcommoncrypto

Using `Cryptor`

let algorithm = Cryptor.Algorithm.aes
var iv = try! Random.generateBytes(byteCount: algorithm.blockSize())
var key = arrayFrom(hexString: "2b7e151628aed2a6abf7158809cf4f3c")
var plainText = "The quick brown fox jumps over the lazy dog. The fox has more or less had it at this point."

var cryptor = Cryptor(operation:.encrypt, algorithm:algorithm, options:.PKCS7Padding, key:key, iv:iv)
var cipherText = cryptor.update(plainText)?.final()

cryptor = Cryptor(operation:.decrypt, algorithm:algorithm, options:.PKCS7Padding, key:key, iv:iv)
var decryptedPlainText = cryptor.update(cipherText!)?.final()
var decryptedString = String(bytes: decryptedPlainText!, encoding: .utf8)
decryptedString
assert(decryptedString == plainText)

Supported Algorithms

• .AES
• .DES
• .TripleDES
• .CAST
• .RC2
• .Blowfish

Using `StreamCryptor`

To encrypt a large file or a network stream use StreamCryptor. The StreamCryptor class does not accumulate the encrypted or decrypted data, instead each call to update produces an output buffer.

The example below shows how to use StreamCryptor to encrypt and decrypt an image file.

func crypt(sc : StreamCryptor,  inputStream: InputStream, outputStream: OutputStream, bufferSize: Int) -> (bytesRead: Int, bytesWritten: Int)
{
    var inputBuffer = Array<UInt8>(repeating:0, count:1024)
    var outputBuffer = Array<UInt8>(repeating:0, count:1024)


    var cryptedBytes : Int = 0
    var totalBytesWritten = 0
    var totalBytesRead = 0
    while inputStream.hasBytesAvailable
    {
        let bytesRead = inputStream.read(&inputBuffer, maxLength: inputBuffer.count)
        totalBytesRead += bytesRead
        let status = sc.update(bufferIn: inputBuffer, byteCountIn: bytesRead, bufferOut: &outputBuffer, byteCapacityOut: outputBuffer.count, byteCountOut: &cryptedBytes)
        assert(status == Status.success)
        if(cryptedBytes > 0)
        {
            let bytesWritten = outputStream.write(outputBuffer, maxLength: Int(cryptedBytes))
            assert(bytesWritten == Int(cryptedBytes))
            totalBytesWritten += bytesWritten
        }
    }
    let status = sc.final(bufferOut: &outputBuffer, byteCapacityOut: outputBuffer.count, byteCountOut: &cryptedBytes)    
    assert(status == Status.success)
    if(cryptedBytes > 0)
    {
        let bytesWritten = outputStream.write(outputBuffer, maxLength: Int(cryptedBytes))
        assert(bytesWritten == Int(cryptedBytes))
        totalBytesWritten += bytesWritten
    }
    return (totalBytesRead, totalBytesWritten)
}

let imagePath = Bundle.main.path(forResource: "Riscal", ofType:"jpg")!
let tmp = NSTemporaryDirectory() as NSString
let encryptedFilePath = "\(tmp)/Riscal.xjpgx"
var decryptedFilePath = "\(tmp)/RiscalDecrypted.jpg"

// Prepare the input and output streams for the encryption operation
guard let imageInputStream = InputStream(fileAtPath: imagePath) else {
    fatalError("Failed to initialize the image input stream.")
}
imageInputStream.open()
guard let  encryptedFileOutputStream = OutputStream(toFileAtPath: encryptedFilePath, append:false) else
{
    fatalError("Failed to open output stream.")
}
encryptedFileOutputStream.open()

// Generate a new, random initialization vector
let initializationVector = try! Random.generateBytes(byteCount: algorithm.blockSize())

// A common way to communicate the initialization vector is to write it at the beginning of the encrypted data.
let bytesWritten = encryptedFileOutputStream.write(initializationVector, maxLength: initializationVector.count)

// Now write the encrypted data
var sc = StreamCryptor(operation:.encrypt, algorithm:algorithm, options:.PKCS7Padding, key:key, iv:initializationVector)
guard  bytesWritten == initializationVector.count else
{
    fatalError("Failed to write initialization vector to encrypted output file.")
}
let outputResult = crypt(sc: sc, inputStream: imageInputStream, outputStream: encryptedFileOutputStream, bufferSize: 1024)
encryptedFileOutputStream.close()
outputResult

// Uncomment this line to verify that the file is encrypted
//var encryptedImage = NSImage(contentsOfFile:encryptedFile)

// Prepare the input and output streams for the decryption operation
guard let encryptedFileInputStream = InputStream(fileAtPath: encryptedFilePath) else
{
    fatalError("Failed to open the encrypted file for input.")
}
encryptedFileInputStream.open()
guard let decryptedFileOutputStream = OutputStream(toFileAtPath: decryptedFilePath, append:false) else {
    fatalError("Failed to open the file for the decrypted output file.")
}
decryptedFileOutputStream.open()

// Read back the initialization vector.
var readbackInitializationVector = Array<UInt8>(repeating: 0, count: algorithm.blockSize())
let bytesRead = encryptedFileInputStream.read(&readbackInitializationVector, maxLength: readbackInitializationVector.count)

// Uncomment this to verify that we did indeed read back the initialization vector.
//assert(readbackInitializationVector == initializationVector)

// Now use the read back initialization vector (along with the key) to
sc = StreamCryptor(operation:.decrypt, algorithm:algorithm, options:.PKCS7Padding, key:key, iv:readbackInitializationVector)
let inputResult = crypt(sc: sc, inputStream: encryptedFileInputStream, outputStream: decryptedFileOutputStream, bufferSize: 1024)

// Uncomment this to verify that decrypt operation consumed all the encrypted data
// and produced the correct number of bytes of plaintext output.
//assert(inputResult.bytesRead == outputResult.bytesWritten && inputResult.bytesWritten == outputResult.bytesRead)

var image = NSImage(named:"Riscal.jpg")
var decryptedImage = NSImage(contentsOfFile:decryptedFilePath)
decryptedImage

Using `PBKDF`

The PBKDF class provides a method of deriving keys from a user password. The following example derives a 20-byte key:

let keys6 = PBKDF.deriveKey("password", salt: "salt", prf: .SHA1, rounds: 1, derivedKeyLength: 20)
// RFC 6070 - Should derive 0c60c80f961f0e71f3a9b524af6012062fe037a6
let expectedRFC6070 = arrayFrom(hexString: "0c60c80f961f0e71f3a9b524af6012062fe037a6")
assert(keys6 == expectedRFC6070)

Supported Pseudo-Random Functions

• .sha1
• .sha224
• .sha256
• .sha384
• .sha512

Package Metadata

Repository: iosdevzone/idzswiftcommoncrypto

Default branch: master

README: README.md