Zig Requires Chilkat v11.0.0+

Verfies an RSA Signature

See more Apple Keychain Examples

Verifies an RSA signature against the original data. 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;

    // The following data was signed by the following example:
    // RSA Sign using a Private Key on a USB Token or Smartcard
    const bd = try chilkat.BinData.init();
    defer bd.deinit();
    var i: i32 = 0;
    i = 0;
    while (i <= 100) : (i += 1) {
        bd.appendEncoded("000102030405060708090A0B0C0D0E0F", "hex") catch {};
    }

    // Load the signature
    const bd_sig = try chilkat.BinData.init();
    defer bd_sig.deinit();
    success = if (bd_sig.loadFile("rsaSignatures/test1.sig")) true else |_| false;
    if (!success) {
        std.debug.print("Failed to load the RSA signature\n", .{});
        return;
    }

    // Get the public key to be used for signature verification.
    const pub_key = try chilkat.PublicKey.init();
    defer pub_key.deinit();
    success = if (pub_key.loadFromFile("rsaKeys/chilkat-rsa-2048.pem")) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try pub_key.getLastErrorText(alloc)});
        return;
    }

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

    // Verify the hash of the data against the signature.
    // We pass in the original data.  Internally, the hash is generated
    // and used to validate the signature.
    // Validating the RSA signature means two things:
    // (1) the original data is exactly what was signed, and
    // (2) it was signed by the owner of the RSA private key.

    success = if (rsa.verifyBd(bd, "sha256", bd_sig)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try rsa.getLastErrorText(alloc)});
        std.debug.print("Signature invalid.\n", .{});
    } else {
        std.debug.print("Signature valid.\n", .{});
    }
}