Zig Requires Chilkat v11.0.0+

RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature. Zig

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

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

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

    const priv_key = try chilkat.PrivateKey.init();
    defer priv_key.deinit();

    // Load the private key from an RSA .key file:
    priv_key.loadPemFile("privateKey.key") catch {
        std.debug.print("{s}\n", .{try priv_key.getLastErrorText(alloc)});
        return;
    };

    const rsa = try chilkat.Rsa.init();
    defer rsa.deinit();

    // Import the private key into the RSA component:
    rsa.usePrivateKey(priv_key) catch {
        std.debug.print("{s}\n", .{try rsa.getLastErrorText(alloc)});
        return;
    };

    // Create the signature as a hex string:
    rsa.setEncodingMode("hex");

    const str_data = "This is the string to be signed.";

    // Sign the string using the sha256 hash algorithm.
    // Other valid choices are "md2", "sha1", "sha384",
    // "sha512", and "md5".
    const hex_sig = try rsa.signStringENC(alloc, str_data, "sha256");

    std.debug.print("{s}\n", .{hex_sig});

    // Load a digital certificate from a .cer file:
    const cert = try chilkat.Cert.init();
    defer cert.deinit();

    cert.loadFromFile("myCert.cer") catch {
        std.debug.print("{s}\n", .{try cert.getLastErrorText(alloc)});
        return;
    };

    const pub_key = try chilkat.PublicKey.init();
    defer pub_key.deinit();
    cert.getPublicKey(pub_key) catch {};

    // Now verify using a new instance of the RSA object:
    const rsa2 = try chilkat.Rsa.init();
    defer rsa2.deinit();

    // Import the public key into the RSA object:
    rsa2.usePublicKey(pub_key) catch {
        std.debug.print("{s}\n", .{try rsa2.getLastErrorText(alloc)});
        return;
    };

    // The signature is a hex string, so make sure the EncodingMode is correct:
    rsa2.setEncodingMode("hex");

    // Verify the signature:
    rsa2.verifyStringENC(str_data, "sha256", hex_sig) catch {
        std.debug.print("{s}\n", .{try rsa2.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("Success.\n", .{});
}