(Swift) Apple Keychain - Create RSA Signature

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Using an RSA private key stored in the Apple Keychain, create a signature by signing the SHA-256 hash of the provided string, then return the signature encoded in Base64 format.

Note: This example requires Chilkat v10.0.0 or greater.

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

    let cert = CkoCert()!

    // On MacOS and iOS, the LoadByCommonName function will search the Apple Keychain for the matching certificate.

    // A digital certificate's Common Name (CN) is a field in the certificate that specifies the name of the entity the 
    // certificate is issued to. It is often used to identify the domain name, hostname, or organization the certificate represents. 

    // For example:
    // - In an SSL/TLS certificate for a website, the CN typically contains the domain name (e.g., "www.example.com").
    // - For certificates representing individuals or organizations, the CN might include the person's name or the organization's name.

    // The CN is part of the certificate's Subject field and is crucial for verifying that the certificate corresponds 
    // to the intended entity, especially in SSL/TLS communications.

    var success: Bool = cert.load(byCommonName: "Example, Inc.")
    if success == false {
        print("\(cert.lastErrorText!)")
        return
    }

    let rsa = CkoRsa()!
    success = rsa.setX509Cert(cert, usePrivateKey: true)
    if success == false {
        print("\(rsa.lastErrorText!)")
        return
    }

    // Generate an RSA signature by signing the SHA-256 hash of the provided string, 
    // then return the signature encoded in Base64 format.
    rsa.encodingMode = "base64"
    var sigBase64: String? = rsa.signStringENC("to be signed", hashAlg: "sha256")
    if rsa.lastMethodSuccess == false {
        print("\(rsa.lastErrorText!)")
        return
    }

    print("RSA Signature:")
    print("\(sigBase64!)")

}