(JavaScript) RSASSA-PSS Sign String to Create Base64 PCKS7 Signature

Signs a string to create a PKCS7 signature in the base64 encoding. The signature algorithm is RSASSA-PSS with SHA256.

Note: This example requires Chilkat v11.0.0 or greater.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

var success = false;

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

var crypt = new CkCrypt2();

// Get a digital certificate with private key from a .pfx
// (Chilkat has many different ways to provide a cert + private key for siging.
// Using a PFX is just one possible option.)
var pfx = new CkPfx();
success = pfx.LoadPfxFile("qa_data/rsassa-pss/privatekey.pfx","PFX_PASSWORD");
if (success == false) {
    console.log(pfx.LastErrorText);
    return;
}

// Get the certificate to be used for signing.
// (The typical case for a PFX is that it contains a cert with an associated private key,
// as well as other certificates in the chain of authentication.  The cert with the private
// key should be in the first position at index 0.)

var cert = new CkCert();
success = pfx.CertAt(0,cert);
if (success == false) {
    console.log(pfx.LastErrorText);
    return;
}

crypt.SetSigningCert(cert);

// Indicate that RSASSA-PSS with SHA256 should be used.
crypt.SigningAlg = "pss";
crypt.HashAlgorithm = "sha256";

crypt.EncodingMode = "base64";

// Sign a string and return the base64 PKCS7 detached signature
var originalText = "This is a test";
var pkcs7sig = crypt.SignStringENC(originalText);
console.log("Detached Signature:");
console.log(pkcs7sig);

// This signature looks like this:
// MIIG5wYJKoZIhvcNAQcCoIIG2DCCBtQCAQExDzANBgl .. YToLqEwTdU87ox5g7rvw==

// The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
// then copy-and-paste the Base64 signature into the form and decode..

// The signature can be verified against the original data like this:
success = crypt.VerifyStringENC(originalText,pkcs7sig);
console.log("Signature verified: " + success);
success = crypt.VerifyStringENC("Not the original text",pkcs7sig);
console.log("Signature verified: " + success);

// Now we'll create an opaque signature (the opposite of a detached signature). 
// An opaque signature is a PKCS7 message that contains both the original data and
// the signature.  The verification process extracts the original data.
var opaqueSig = crypt.OpaqueSignStringENC(originalText);
console.log("Opaque Signature:");
console.log(opaqueSig);

// The ASN.1 of the signature can be examined by browsing to https://lapo.it/asn1js/ ,
// then copy-and-paste the Base64 signature into the form and decode..

// We can verify and extract the original data:
var origTxt = crypt.OpaqueVerifyStringENC(opaqueSig);
if (crypt.LastMethodSuccess !== true) {
    console.log("Signature verification failed.");
    console.log(crypt.LastErrorText);
    return;
}

console.log("Signature verified.");
console.log("Extracted text:" + origTxt);