Zig Requires Chilkat v11.0.0+

RSA Sign with PKCS8 Encrypted Key

See more RSA Examples

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it). Zig

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

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

    var success: bool = false;

    // 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 PEM file:
    success = if (priv_key.loadAnyFormatFile("raul_privateKey.key", "a0123456789")) true else |_| false;
    if (!success) {
        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:
    success = if (rsa.usePrivateKey(priv_key)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try rsa.getLastErrorText(alloc)});
        return;
    }

    // This example will sign a string, and receive the signature
    // in a hex-encoded string.  Therefore, set the encoding mode
    // to "hex":
    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 sha1, sha384, sha512 and others.
    const hex_sig = rsa.signStringENC(alloc, str_data, "sha256") catch {
        std.debug.print("{s}\n", .{try rsa.getLastErrorText(alloc)});
        return;
    };

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

    // Now verify with the public key.
    // This example shows how to use the public key from
    // a digital certificate (.cer file)
    const cert = try chilkat.Cert.init();
    defer cert.deinit();
    success = if (cert.loadFromFile("raul_publicKey.cer")) true else |_| false;
    if (!success) {
        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 {};

    const rsa2 = try chilkat.Rsa.init();
    defer rsa2.deinit();
    success = if (rsa2.usePublicKey(pub_key)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try rsa2.getLastErrorText(alloc)});
        return;
    }

    // Verify the signature against the original data:
    rsa2.setEncodingMode("hex");
    success = if (rsa2.verifyStringENC(str_data, "sha256", hex_sig)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try rsa2.getLastErrorText(alloc)});
        return;
    }

    std.debug.print("Signature verified!\n", .{});

    // Verify with incorrect data:
    success = if (rsa2.verifyStringENC("something else", "sha256", hex_sig)) true else |_| false;
    if (!success) {
        std.debug.print("Signature not verified! (which was expected in this case)\n", .{});
    } else {
        std.debug.print("Hmmm... that's not right...\n", .{});
    }
}