Zig Requires Chilkat v11.0.0+

RSA Encrypt String to Encoded Result and Reverse

See more RSA Examples

Demonstrates how to RSA encrypt a string to a base64 encoded result, and the reverse. 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 RSA public key is used for encryption, and the private key for decryption.

    // The public key's role is to make encryption accessible to anyone while ensuring that
    // only the private key holder can decrypt the messages.
    // The public key is designed to be widely distributed so anyone can use it to encrypt messages
    // intended for the owner of the private key.

    // Load our 2048-bit RSA public key.
    const pub_key = try chilkat.PublicKey.init();
    defer pub_key.deinit();
    // In all Chilkat methods expecting a path, you pass either absolute or relative paths.
    success = if (pub_key.loadFromFile("rsaKeys/myTestRsaPublic.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();

    // Tell RSA to use the public key.
    rsa.usePublicKey(pub_key) catch {};

    // RSA encryption is for small amounts of data, on the order of 200 bytes or less.
    // The maximum number of bytes that can be RSA encrypted depends
    // on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
    // For specific limits, see: RSA Encryption Maximum Number of Bytes

    // Encrypt the utf-8 byte representation of the string.
    rsa.setCharset("utf-8");
    rsa.setEncodingMode("base64");

    // Be Careful when Using non-us-ascii String Literals in Source Code
    const encrypted_b64 = try rsa.encryptStringENC(alloc, "Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux", false);

    // ------------------------------------------------------------------------------------------------------------------------
    // Let's decrypt, which requires the matching private key...

    // Load the matching 2048-bit RSA private key.
    const priv_key = try chilkat.PrivateKey.init();
    defer priv_key.deinit();
    const password = "secret";
    success = if (priv_key.loadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem", password)) true else |_| false;
    if (!success) {
        std.debug.print("{s}\n", .{try priv_key.getLastErrorText(alloc)});
        return;
    }

    // Tell the RSA object to use the private key.
    rsa.usePrivateKey(priv_key) catch {};

    // Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
    rsa.setCharset("utf-8");
    rsa.setEncodingMode("base64");
    const original_text = try rsa.decryptStringENC(alloc, encrypted_b64, true);
    if (!success) {
        std.debug.print("{s}\n", .{try rsa.getLastErrorText(alloc)});
        return;
    }

    std.debug.print("Original text = {s}\n", .{original_text});
    std.debug.print("Success.\n", .{});
}