Swift

Create and Verify an Opaque PKCS7/CMS Signature

See more Digital Signatures Examples

Demonstrates how to create a PKCS7 opaque signature, and also how to verify an opaque signature. An opaque signature is different than a detached PKCS7 signature in that it contains the original data. Verifying an opaque signature retrieves the original content. 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 crypt = CkoCrypt2()!

    // A certificate and private key is needed to create a signature.
    // Chilkat provides many different ways to load a certificate and private key, such
    // as from a PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
    // This example will load the certificate from a .crt and the private key from a .key file

    let cert = CkoCert()!
    // The LoadFromFile method will automatically detect the format and load it.
    success = cert.load(fromFile: "qa_data/certs/test_12345678a.cer")
    if success != true {
        print("\(cert.lastErrorText!)")
        return
    }

    // Our private key is in an encrypted PKCS8 format.
    // If you don't know the format of your key, but you do know it's encrypted,
    // and requires a password, then just call any of the Chilkat methods that load
    // a private key w/ a password argument.  Chilkat will auto-detect the format
    // and load it correctly even if it's not the format indicated by the method name..
    let privKey = CkoPrivateKey()!
    var password: String? = "12345678a"
    success = privKey.loadPkcs8EncryptedFile(path: "qa_data/certs/test_12345678a.key", password: password)
    if success != true {
        print("\(privKey.lastErrorText!)")
        return
    }

    // Set properties required for signing.

    // Tell it to use the cert and private key we've loaded.
    success = crypt.setSigningCert2(cert: cert, key: privKey)
    if success != true {
        print("\(crypt.lastErrorText!)")
        return
    }

    // Indicate we want the opaque signature in base64 format:
    crypt.encodingMode = "base64"

    // Sign the string using the "utf-8" byte representation:
    crypt.charset = "utf-8"

    // Create the opaque signature:
    var originalData: String? = "This is the string to be signed."
    var opaqueSig: String? = crypt.opaqueSignStringENC(str: originalData)
    if crypt.lastMethodSuccess != true {
        print("\(crypt.lastErrorText!)")
        return
    }

    print("\(opaqueSig!)")

    // The output looks like this:
    // MIIPgQYJKoZIhvcNAQcCoIIPcjCCD24CAQExCzAJBgUrDgMCGgUAMC8GCSqGSIb3DQEHAaAiBCBUaGlzIGlzIHRoZSBzdHJpbmcgdG8gYmUgc...

    // ----------------------------------------------------------------------------------------------
    // Now let's verify the signature and retrieve the original data.
    // We'll use a new Crypt2 object to keep things completely separate...

    let vCrypt = CkoCrypt2()!

    vCrypt.encodingMode = "base64"
    vCrypt.charset = "utf-8"

    var extractedData: String? = vCrypt.opaqueVerifyStringENC(p7m: opaqueSig)
    if vCrypt.lastMethodSuccess != true {
        print("\(vCrypt.lastErrorText!)")
        return
    }

    print("The extracted data: \(extractedData!)")

    // The output is:
    // The extracted data: This is the string to be signed.

}