(Node.js) Extract PKCS7 Signature Digest

Demonstrates how to extract a signature digest from a PKCS7 signature.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node11-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node11-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node11-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node11-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node11-linux64');
    }
} else if (os.platform() == 'darwin') {
    var chilkat = require('@chilkat/ck-node11-macosx');
}

function chilkatExample() {

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

    var crypt = new chilkat.Crypt2();

    var p7mFile = "qa_data/p7m/test.pdf.p7m";
    var outPath = "qa_output/test.pdf";

    // First let's see if this .p7m signature can be verified, and the original file extracted.
    var verified = crypt.VerifyP7M(p7mFile,outPath);
    if (verified !== true) {
        console.log(crypt.LastErrorText);
        return;
    }

    // How many signers?
    // (The NumSignerCerts property is set whenever a signature is verified.)
    console.log("Num Signers: " + crypt.NumSignerCerts);

    // Load the .p7m into memory...
    var pkcs7Data = new chilkat.BinData();
    pkcs7Data.LoadFile(p7mFile);

    // Check to see if this .p7m contains the binary bytes, or if it's
    // already base64 encoded.  Get the 1st two bytes.  If the first two 
    // bytes are the us-ascii values "MI", then we have base64.
    var sbBase64 = new chilkat.StringBuilder();
    var hexStr = pkcs7Data.GetEncodedChunk(0,2,"hex");
    sbBase64.Append(hexStr);

    var bHaveBase64 = false;
    if (sbBase64.ContentsEqual("4D49",true) == true) {
        bHaveBase64 = true;
        sbBase64.Clear();
        sbBase64.AppendBd(pkcs7Data,"utf-8",0,0);
    }

    // Get each signer's signature digest.
    crypt.EncodingMode = "base64";
    var i = 0;
    var digest;
    while (i < crypt.NumSignerCerts) {
        if (bHaveBase64) {
            digest = crypt.Pkcs7ExtractDigest(i,sbBase64.GetAsString());
        }
        else {
            digest = crypt.Pkcs7ExtractDigest(i,pkcs7Data.GetEncoded("base64"));
        }

        if (crypt.LastMethodSuccess !== true) {
            console.log(crypt.LastErrorText);
            return;
        }

        console.log("Signer " + (i+1) + " digest = " + digest);
        i = i+1;
    }


}

chilkatExample();