Zig Requires Chilkat v11.0.0+

Aadhaar Paperless Offline e-kyc

See more XML Digital Signatures Examples

Opens an encrypted .zip containing Aadhaar Paperless Offline e-KYC XML. Gets the XML and validates the digital signature. Then computes the hash for the mobile number and Email ID. Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

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

    // Open the .zip containing the Aadhaar Paperless Offline e-KYC XML.
    // The .zip is encrypted using the "Share Phrase".
    const zip = try chilkat.Zip.init();
    defer zip.deinit();
    zip.openZip("qa_data/xml_dsig/offline_paperless_kyc.zip") catch {
        std.debug.print("{s}\n", .{try zip.getLastErrorText(alloc)});
        return;
    };

    // The .zip should contain 1 XML file.
    const entry = try chilkat.ZipEntry.init();
    defer entry.deinit();
    zip.entryAt(0, entry) catch {
        std.debug.print("{s}\n", .{try zip.getLastErrorText(alloc)});
        return;
    };

    // To get the contents, we need to specify the Share Phrase.
    const share_phrase = "Lock@487";
    zip.setDecryptPassword(share_phrase);

    const bd_xml = try chilkat.BinData.init();
    defer bd_xml.deinit();
    // The XML file will be unzipped into the bdXml object.
    entry.unzipToBd(bd_xml) catch {
        std.debug.print("{s}\n", .{try entry.getLastErrorText(alloc)});
        return;
    };

    // First verify the XML digital signature.
    const dsig = try chilkat.XmlDSig.init();
    defer dsig.deinit();
    dsig.loadSignatureBd(bd_xml) catch {
        std.debug.print("{s}\n", .{try dsig.getLastErrorText(alloc)});
        return;
    };

    // The UIDAI XML signature does not contain the KeyInfo, so we must load the uidai certificate
    // and indicate that its public key is to be used for verifying the signature.
    const cert = try chilkat.Cert.init();
    defer cert.deinit();
    cert.loadFromFile("qa_data/xml_dsig/uidai_auth_sign_prod_2023.cer") catch {
        std.debug.print("{s}\n", .{try cert.getLastErrorText(alloc)});
        return;
    };

    // Get the certificate's public key.
    const pub_key = try chilkat.PublicKey.init();
    defer pub_key.deinit();
    cert.getPublicKey(pub_key) catch {};

    dsig.setPublicKey(pub_key) catch {};

    // The XML in this example contains only 1 signature.
    const b_verify_reference_digests = true;
    dsig.verifySignature(b_verify_reference_digests) catch {
        std.debug.print("{s}\n", .{try dsig.getLastErrorText(alloc)});
        std.debug.print("The signature was not valid.\n", .{});
        return;
    };

    std.debug.print("The XML digital signature is valid.\n", .{});

    // Let's compute the hash for the Mobile Number.

    //     Hashing logic for Mobile Number :
    //     Sha256(Sha256(Mobile+SharePhrase))*number of times last digit of Aadhaar number
    //     (Ref ID field contains last 4 digits).
    //
    //     Example :
    //     Mobile: 1234567890
    //     Aadhaar Number:XXXX XXXX 3632
    //     Passcode : Lock@487
    //     Hash: Sha256(Sha256(1234567890Lock@487))*2
    //     In case of Aadhaar number ends with Zero we will hashed one time.

    const crypt = try chilkat.Crypt2.init();
    defer crypt.deinit();
    crypt.setHashAlgorithm("sha256");
    crypt.setEncodingMode("hexlower");

    var str_to_hash: [:0]const u8 = "1234567890Lock@487";
    const bd_hash = try chilkat.BinData.init();
    defer bd_hash.deinit();
    try bd_hash.appendString(str_to_hash, "utf-8");

    // Hash a number of times equal to the last digit of your Aadhaar number.
    // If the Aadhaar number ends with 0, then hash one time.
    // For this example, we'll just set the number of times to hash
    // for the case where an Aadhaar number ends in "9"
    const num_times_to_hash = 9;
    var i: i32 = 0;
    i = 1;
    while (i <= num_times_to_hash) : (i += 1) {
        const tmp_str = try crypt.hashBdENC(alloc, bd_hash);
        bd_hash.clear() catch {};
        bd_hash.appendString(tmp_str, "utf-8") catch {};
    }

    std.debug.print("Computed Mobile hash = {s}\n", .{try bd_hash.getString(alloc, "utf-8")});

    // Let's get the mobile hash stored in the XML and compare it with our computed hash.
    const xml = try chilkat.Xml.init();
    defer xml.deinit();
    try xml.loadBd(bd_xml, true);
    const m_hash = try xml.chilkatPath(alloc, "UidData|Poi|(m)");

    std.debug.print("Stored Mobile hash   = {s}\n", .{m_hash});

    // Now do the same thing for the email hash:

    str_to_hash = "abc@gm.comLock@487";
    bd_hash.clear() catch {};
    try bd_hash.appendString(str_to_hash, "utf-8");

    i = 1;
    while (i <= num_times_to_hash) : (i += 1) {
        const tmp_str = try crypt.hashBdENC(alloc, bd_hash);
        bd_hash.clear() catch {};
        bd_hash.appendString(tmp_str, "utf-8") catch {};
    }

    std.debug.print("Computed Email hash = {s}\n", .{try bd_hash.getString(alloc, "utf-8")});

    const e_hash = try xml.chilkatPath(alloc, "UidData|Poi|(e)");
    std.debug.print("Stored Email hash   = {s}\n", .{e_hash});
}