Zig

AES Encrypt and Decrypt a File

_LANGUAGE_ demonstrates how to AES encrypt a file of any size, and then decrypt. Zig

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

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

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    const crypt = try chilkat.Crypt2.init();
    defer crypt.deinit();

    crypt.setCryptAlgorithm("aes");

    // CipherMode may be "ecb" or "cbc"
    crypt.setCipherMode("cbc");

    // KeyLength may be 128, 192, 256
    crypt.setKeyLength(256);

    // The padding scheme determines the contents of the bytes
    // that are added to pad the result to a multiple of the
    // encryption algorithm's block size.  AES has a block
    // size of 16 bytes, so encrypted output is always
    // a multiple of 16.
    crypt.setPaddingScheme(0);

    // An initialization vector is required if using CBC mode.
    // ECB mode does not use an IV.
    // The length of the IV is equal to the algorithm's block size.
    // It is NOT equal to the length of the key.
    const iv_hex = "000102030405060708090A0B0C0D0E0F";
    crypt.setEncodedIV(iv_hex, "hex");

    // The secret key must equal the size of the key.  For
    // 256-bit encryption, the binary secret key is 32 bytes.
    // For 128-bit encryption, the binary secret key is 16 bytes.
    const key_hex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";
    crypt.setEncodedKey(key_hex, "hex");

    // Encrypt a file, producing the .aes as output.
    // The input file is unchanged, the output .aes contains the encrypted
    // contents of the input file.

    // Note: The .aes output file has no file format.  It is simply a stream
    // of bytes that resembles random binary data.
    var in_file: [:0]const u8 = "/Users/chilkat/testData/pdf/sample.pdf";
    var out_file: [:0]const u8 = "/Users/chilkat/testData/p7m/sample.pdf.aes";
    crypt.ckEncryptFile(in_file, out_file) catch {
        std.debug.print("{s}\n", .{try crypt.getLastErrorText(alloc)});
        return;
    };

    // For demonstration purposes, a different instance of the object will be used
    // for decryption.
    const decrypt = try chilkat.Crypt2.init();
    defer decrypt.deinit();

    // All settings must match to be able to decrypt:
    decrypt.setCryptAlgorithm("aes");
    decrypt.setCipherMode("cbc");
    decrypt.setKeyLength(256);
    decrypt.setPaddingScheme(0);
    decrypt.setEncodedIV(iv_hex, "hex");
    decrypt.setEncodedKey(key_hex, "hex");

    // Decrypt the .aes
    in_file = "/Users/chilkat/testData/p7m/sample.pdf.aes";
    out_file = "/Users/chilkat/testData/pdf/recovered.pdf";
    decrypt.ckDecryptFile(in_file, out_file) catch {
        std.debug.print("{s}\n", .{try decrypt.getLastErrorText(alloc)});
        return;
    };

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