Swift

CMS Sign Hash

Demonstrates how to use the SignHashENC method to sign a pre-computed hash. This method creates a CMS signature (PKCS7 detached signature).

This example requires Chilkat v9.5.0.90 or later.

Swift

func chilkatTest() {
    var success: Bool = false

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

    let crypt = CkoCrypt2()!

    // Create the hash to be signed...
    crypt.hashAlgorithm = "sha256"
    crypt.encodingMode = "base64"
    crypt.charset = "utf-8"
    // Create the SHA256 hash of a string using the utf-8 byte representation.
    // Return the hash as base64.
    var base64Hash: String? = crypt.hashStringENC(str: "This is the string to be hashed")

    // Load a certificate for signing.
    let cert = CkoCert()!
    success = cert.loadPfxFile(path: "qa_data/pfx/cert_test123.pfx", password: "test123")
    if success == false {
        print("\(cert.lastErrorText!)")
        return
    }

    crypt.setSigningCert(cert: cert)

    // Sign the hash to create a base64 CMS signature (which does not contain the original data).
    // We can get the signature in a single line of base64 by specifying "base64", or 
    // we can get multi-line base64 by specifying "base64_mime".
    crypt.encodingMode = "base64_mime"
    var base64CmsSig: String? = crypt.signHashENC(encodedHash: base64Hash, hashAlg: "sha256", hashEncoding: "base64")
    if crypt.lastMethodSuccess == false {
        print("\(crypt.lastErrorText!)")
        return
    }

    // Note: In the above call to SignHashENC, the encoding of the returned CMS signature is specified by the EncodingMode property.
    // However, the encoding of the passed-in hash is indicated by the 3rd argument.

    print("CMS Signature: \(base64CmsSig!)")

}