(Swift 3,4,5...) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

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

    let pkey = CkoPrivateKey()!

    // Load the private key from an RSA PEM file:
    var success: Bool = pkey.loadPkcs8EncryptedFile("raul_privateKey.key", password: "a0123456789")

    var pkeyXml: String?
    // Get the private key in XML format:
    pkeyXml = pkey.getXml()

    let rsa = CkoRsa()!

    // Import the private key into the RSA component:
    success = rsa.importPrivateKey(pkeyXml)
    if success != true {
        print("\(rsa.lastErrorText!)")
        return
    }

    // This example will sign a string, and receive the signature
    // in a hex-encoded string.  Therefore, set the encoding mode
    // to "hex":
    rsa.encodingMode = "hex"

    var strData: String? = "This is the string to be signed."

    // Sign the string using the sha-1 hash algorithm.
    // Other valid choices are "md2" and "md5".
    var hexSig: String? = rsa.signStringENC(strData, hashAlg: "sha-1")

    print("\(hexSig!)")

    // Now verify with the public key.
    // This example shows how to use the public key from 
    // a digital certificate (.cer file)
    let cert = CkoCert()!
    success = cert.load(fromFile: "raul_publicKey.cer")
    if success != true {
        print("\(cert.lastErrorText!)")
        return
    }

    var pubKey: CkoPublicKey?
    pubKey = cert.exportPublicKey()

    var pubKeyXml: String?
    // Get the private key in XML format:
    pubKeyXml = pubKey!.getXml()

    let rsa2 = CkoRsa()!
    success = rsa2.importPublicKey(pubKeyXml)
    if success != true {
        print("\(rsa2.lastErrorText!)")
        return
    }

    // Verify the signature against the original data:
    rsa2.encodingMode = "hex"
    success = rsa2.verifyStringENC(strData, hashAlg: "sha-1", sig: hexSig)
    if success != true {
        print("\(rsa2.lastErrorText!)")
        return
    }

    print("Signature verified!")

    // Verify with incorrect data:
    success = rsa2.verifyStringENC("something else", hashAlg: "sha-1", sig: hexSig)
    if success != true {
        print("Signature not verified! (which was expected in this case)")
    }
    else {
        print("Hmmm... that's not right...")
    }

    pubKey = nil

}