(Swift 3,4,5...) Encrypt File using X.509 Certificate using AES in CBC Mode

Demonstrates how to encrypt a file using an X.509 Certificate's public key, where the underlying bulk encryption algorithm is 128-bit AES in CBC mode. (The underlying bulk encryption algorithm can be specified to be other algorithms/strengths.)

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

    let crypt = CkoCrypt2()!

    // Use public-key cryptography for encryption.
    crypt.cryptAlgorithm = "pki"

    // Get an X.509 certificate to use for encrypting.
    // Note: Chilkat provides many different ways of loading a certificate, from many different formats,
    // or if on Windows, from the installed certificates on the system.
    // This example simply loads a certificate from a file.
    // Also, for encryption, only the public key is needed.  Digital certificates embed the public key
    // within the X.509 format itself.  Therefore, if you have a certificate, you also have the public key.
    let cert = CkoCert()!
    var success: Bool = cert.load(fromFile: "qa_data/certs/testCert.cer")
    if success != true {
        print("\(cert.lastErrorText!)")
        return
    }

    success = crypt.setEncryptCert(cert)
    if success != true {
        print("\(crypt.lastErrorText!)")
        return
    }

    // Indicate the underlying bulk encryption algorithm to be used:
    crypt.pkcs7CryptAlg = "aes"
    crypt.keyLength = 128

    // Note: When doing public-key encryption the underlying bulk symmetric cipher mode will always be CBC. (at least with Chilkat...)

    // There's one last option that could be set.  If is the RSA encryption encryption/padding scheme. 
    // By default, RSAES_PKCS1-V1_5 is used.  If desired, the OaepPadding property could be set to true to
    // use RSAES_OAEP.  (We'll leave it set at the default value of false)
    crypt.oaepPadding = false

    // Everything is specified.  Now just encrypt...
    // The output is PKCS7 in binary DER format.
    success = crypt.ckEncryptFile("qa_data/hamlet.xml", destFile: "qa_output/hamlet.p7")
    if success != true {
        print("\(crypt.lastErrorText!)")
        return
    }

    print("Finished.")

}