Zig Requires Chilkat v11.0.0+

Verify an RSA Signature Against the Signed Hash

See more Apple Keychain Examples

Demonstrates how to validate an RSA Signature against the hash that was signed. 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;

    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 {};
    }

    const sha256_base64 = try bd.getHash(alloc, "sha256", "base64");
    std.debug.print("sha256 hash in base64 format: {s}\n", .{sha256_base64});

    const base64_rsa_sig = "AwF2BbOvL6jA5DwmMAc9n6J2Cc8PI6Rj5W079+aKJcIEtPWRzHor0Bvc3aftGM3Jbgj6SXlIC3M3RYS7UZOnfiHKFNZgbxaNT5WwsWooK42ZkC8DBZl0p7OunBUKd5SciUo+TKilioeUkriN3L1Zl9hwi3HVDVqgVo3XXskwIftSqLSFlepTLTmOWj9Y93dp8J4D9RyLtNgFQBc0WB22tyJTsuY56mLcWe1AMF3LizB9OrbwjynF2u16xWlrJdugccz795fJBUV9aQSD+8S3KeqwQhoi8RK1uhD68aGCyaSpBq0NZ8COAkn7MXaF4POxrAAt8udfHM+PRfSOptcH/w==";

    // 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 against the signature.
    rsa.setEncodingMode("base64");

    success = if (rsa.verifyHashENC(sha256_base64, "sha256", base64_rsa_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", .{});
    }
}