Swift

Generating Repeatable Random Data for Testing/Debugging

See more PRNG Examples

Demonstrates how to use the Fortuna PRNG to generate random-looking but repeatable non-random data for the purpose of testing and debugging. Swift

func chilkatTest() {
    var success: Bool = false

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    success = false

    let fortuna = CkoPrng()!

    // Normally an application would seed the PRNG with entropy from
    // some real random source.  However, sometimes we want the same
    // random sequence of bytes for testing and debugging purposes.
    // This a reason why GetEntropy and AddEntropy are two different methods.
    // An application could omit the call to GetEntropy, and instead pass
    // non-random data to AddEntropy. For example:

    // Seed the PRNG with non-entropy, so we get a repeatable sequence.
    // Note: AddEntropy can be called any number of times.
    success = fortuna.addEntropy(entropy: "01020304", encoding: "hex")
    success = fortuna.addEntropy(entropy: "hello world", encoding: "ascii")

    // Generate some random data:
    var strRandHex: String? = fortuna.genRandom(numBytes: 16, encoding: "hex")
    var strRandBase64: String? = fortuna.genRandom(numBytes: 22, encoding: "base64")
    var strRandBase58: String? = fortuna.genRandom(numBytes: 32, encoding: "base58")

    print("hex random bytes: \(strRandHex!)")
    print("base64 random bytes: \(strRandBase64!)")
    print("base58 random bytes: \(strRandBase58!)")

    // Try it again with a different object to verify that the same results are obtained:
    let fortuna2 = CkoPrng()!

    success = fortuna2.addEntropy(entropy: "01020304", encoding: "hex")
    success = fortuna2.addEntropy(entropy: "hello world", encoding: "ascii")

    strRandHex = fortuna2.genRandom(numBytes: 16, encoding: "hex")
    strRandBase64 = fortuna2.genRandom(numBytes: 22, encoding: "base64")
    strRandBase58 = fortuna2.genRandom(numBytes: 32, encoding: "base58")

    print("hex random bytes: \(strRandHex!)")
    print("base64 random bytes: \(strRandBase64!)")
    print("base58 random bytes: \(strRandBase58!)")

}