Swift

RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature. 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.

    let privKey = CkoPrivateKey()!

    // Load the private key from an RSA .key file:
    success = privKey.loadPemFile(path: "privateKey.key")
    if success == false {
        print("\(privKey.lastErrorText!)")
        return
    }

    let rsa = CkoRsa()!

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

    // Create the signature as a hex string:
    rsa.encodingMode = "hex"

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

    // Sign the string using the sha256 hash algorithm.
    // Other valid choices are "md2", "sha1", "sha384",
    // "sha512", and "md5".
    var hexSig: String? = rsa.signStringENC(str: strData, hashAlg: "sha256")

    print("\(hexSig!)")

    // Load a digital certificate from a .cer file:
    let cert = CkoCert()!

    success = cert.load(fromFile: "myCert.cer")
    if success == false {
        print("\(cert.lastErrorText!)")
        return
    }

    let pubKey = CkoPublicKey()!
    cert.getPublicKey(pubKey: pubKey)

    // Now verify using a new instance of the RSA object:
    let rsa2 = CkoRsa()!

    // Import the public key into the RSA object:
    success = rsa2.usePublicKey(pubKey: pubKey)
    if success == false {
        print("\(rsa2.lastErrorText!)")
        return
    }

    // The signature is a hex string, so make sure the EncodingMode is correct:
    rsa2.encodingMode = "hex"

    // Verify the signature:
    success = rsa2.verifyStringENC(str: strData, hashAlg: "sha256", sig: hexSig)
    if success == false {
        print("\(rsa2.lastErrorText!)")
        return
    }

    print("Success.")

}