Zig

Compress and Encrypt a Large File (Low and Constant Memory Footprint)

See more Compression Examples

Demonstrates how to compress and encrypt a large file such that the memory footprint remains low and constant.

Note: This example requires Chilkat v9.5.0.99 or greater.

Zig

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

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

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

    const compress = try chilkat.Compression.init();
    defer compress.deinit();
    compress.setAlgorithm("deflate");

    // Set encryption params.
    // The possible values are the same as for the corresponding properties in the Chilkat Crypt2 class/object.
    // The encoded IV and Key must be specified as hex.
    const json = try chilkat.JsonObject.init();
    defer json.deinit();
    json.updateString("cryptAlgorithm", "aes") catch {};
    json.updateString("cipherMode", "cbc") catch {};
    json.updateInt("keyLength", 128) catch {};
    json.updateInt("paddingScheme", 0) catch {};
    json.updateString("encodedIV", "000102030405060708090A0B0C0D0E0F") catch {};
    json.updateString("encodedKey", "000102030405060708090A0B0C0D0E0F") catch {};

    // Do file-to-file compression+encryption in a single call.
    const in_path = "qa_data/largeFile.dat";
    const out_path = "c:/temp/qa_output/compressed_encrypted.dat";
    compress.compressEncryptFile(json, in_path, out_path) catch {
        std.debug.print("{s}\n", .{try compress.getLastErrorText(alloc)});
        return;
    };

    // We can do file-to-file decrypt/decompress like this:
    const in_path2 = out_path;
    const out_path2 = "c:/temp/qa_output/restored.dat";
    compress.decryptDecompressFile(json, in_path2, out_path2) catch {
        std.debug.print("{s}\n", .{try compress.getLastErrorText(alloc)});
        return;
    };

    // Note: The above decrypt + decompress is the equivalent of doing the same in these two steps:
    const crypt = try chilkat.Crypt2.init();
    defer crypt.deinit();
    crypt.setCryptAlgorithm("aes");
    crypt.setCipherMode("cbc");
    crypt.setKeyLength(128);
    crypt.setPaddingScheme(0);
    crypt.setEncodedIV("000102030405060708090A0B0C0D0E0F", "hex");
    crypt.setEncodedKey("000102030405060708090A0B0C0D0E0F", "hex");

    const decrypted_path = "c:/temp/qa_output/decrypted.dat";
    crypt.ckDecryptFile(in_path2, decrypted_path) catch {
        std.debug.print("{s}\n", .{try crypt.getLastErrorText(alloc)});
        return;
    };

    const out_path3 = "c:/temp/qa_output/restored_in_two_steps.dat";
    compress.decompressFile(decrypted_path, out_path3) catch {
        std.debug.print("{s}\n", .{try compress.getLastErrorText(alloc)});
        return;
    };

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