Zig Requires Chilkat v11.0.0+

Demonstrate RSA Encrypt/Decrypt using BinData

See more RSA Examples

Demonstrates how to RSA encrypt and decrypt data contained in a Chilkat BinData object. Zig

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

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

    // 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.
    pub_key.loadFromFile("rsaKeys/myTestRsaPublic.pem") catch {
        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

    // Create some binary data to encrypt.
    const bd = try chilkat.BinData.init();
    defer bd.deinit();
    var i: i32 = 0;
    i = 0;
    while (i <= 49) : (i += 1) {
        bd.appendByte(i) catch {};
    }

    // Show the bytes to be encrypted in hex format:
    std.debug.print("To be encrypted: {s}\n", .{try bd.getEncoded(alloc, "hex")});

    // To be encrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031

    // RSA encrypt the contents of the bd, replacing the contents with the RSA encrypted data.
    rsa.encryptBd(bd, false) catch {};

    // Now it is encrypted.
    std.debug.print("Encrypted size = {d}\n", .{bd.getNumBytes()});
    std.debug.print("{s}\n", .{try bd.getEncoded(alloc, "hex")});

    // Encrypted size = 256
    // 749ED9D0A8767C06C09AD9697F654F86B145F966722F9714902C4175BDBD02E68984ECF111D4D461
    // EDB4A8E677D399D19CCA60F35C6DE9972F4262880FE9D77DB75915393E8E7DB80AAB5E383013FAEB
    // 60C77D1E6FECC9A7C8426976416C6218FE7DA998EE063CE709E79C240F8625F4A56A0A33AFD63F7A
    // BA26F2A692B42E878C53B78602C725FE63FF961A46A2B9D436E5E3D9D64AE3F1D1F5AD5F5B47FCD69
    // 447306B77F2FD6D766CCAA1A110A3371586B43DF0D7FFE2220D1B305CF9371AC342F849FB0C90CD99E
    // C176928D877FE1C0DE1A7CB6EB824FEC7E1DCF90EF2C6BA9F1DFD3EBFBE89C51AF074DC6AE02E544A78
    // 5018C36D3D48B2EF5202AF61AC

    // ------------------------------------------------------------------------------------------------------------------------
    // 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";
    priv_key.loadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem", password) catch {
        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 {};

    // Decrypt
    rsa.decryptBd(bd, true) catch {
        std.debug.print("{s}\n", .{try rsa.getLastErrorText(alloc)});
        return;
    };

    // Examine the contents of bd to see if it now contains the unencrypted original data.
    std.debug.print("Decrypted: {s}\n", .{try bd.getEncoded(alloc, "hex")});

    // Decrypted: 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F3031
}