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AES and CHACHA20 Encrypt/Decrypt Text

See more Encryption Examples

Demonstrates the use of the new EncryptSb and DecryptSb methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt the contents of StringBuilder objects.

Note: This example requires Chilkat v9.5.0.67 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.

    // First build a string to be encrypted
    const sb = try chilkat.StringBuilder.init();
    defer sb.deinit();
    var i: i32 = 1;
    while (i < 10) {
        sb.appendInt(i) catch {};
        sb.append(" the quick brown fox jumped over the lazy dog.\r\n") catch {};
        i = i + 1;
    }

    std.debug.print("{s}\n", .{try sb.getAsString(alloc)});

    // The string to be encrypted looks like this:

    // 1 the quick brown fox jumped over the lazy dog.
    // 2 the quick brown fox jumped over the lazy dog.
    // 3 the quick brown fox jumped over the lazy dog.
    // 4 the quick brown fox jumped over the lazy dog.
    // 5 the quick brown fox jumped over the lazy dog.
    // 6 the quick brown fox jumped over the lazy dog.
    // ...

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

    // Specify the encryption to be used.
    // First we'll do AES-128 CBC
    crypt.setCryptAlgorithm("aes");
    crypt.setCipherMode("cbc");
    crypt.setKeyLength(128);

    const iv_hex = "000102030405060708090A0B0C0D0E0F";
    crypt.setEncodedIV(iv_hex, "hex");

    const key_hex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";
    crypt.setEncodedKey(key_hex, "hex");

    // When EncryptSb is called, the contents of the source (sb)
    // remains unmodified.  The encrypted bytes are written into bdEncrypted.
    // If bdEncrypted already contained data, it is replaced with the encrypted bytes.
    const bd_encrypted = try chilkat.BinData.init();
    defer bd_encrypted.deinit();
    crypt.encryptSb(sb, bd_encrypted) catch {
        std.debug.print("{s}\n", .{try crypt.getLastErrorText(alloc)});
        return;
    };

    // Examine the encrypted bytes:
    std.debug.print("{s}\n", .{try bd_encrypted.getEncoded(alloc, "base64_mime")});

    // Sample encrypted data:

    // 0DdNZ22ckMMJBiaKhAu3wUEfh16XW356NIUsDmNs/xwbHe/p1201OmpfzwXwKktkAefu2pckrBgC
    // df+1w8lRo+KAy5n5wlAgMGM/UrsVJsp0BmDPk1vaxKrmrGpSXOVCQs1n2+0atIs5YLiOG+Va3+Mi
    // EQNb4YK7bNMmvt0++irBxTiGnkx/RncfKwgkbBUpl2x7yV13MW6lapDT6Md0DKAMsTXFJYGeIdEf
    // g2uxDDQzI5gUOUHTMrXQ8paD/K76KKB9Jpp/kAM9z8g/d8KUmuphA7KI64d38xsgOmcITlbhlCQ2
    // PDkcU6RRzX0FUTUSMgQukhy0jkLZEjHX9poKJD+iJTOkcQUC3OqR9hKhSrvIgJN4lxdR71MheOoQ
    // 2wmvRdq+agTWWh333Vmb6J6yDV79aSpnqEDrA8Ks7Xzciol0gve91+JtVJlJKjWwEzWEU8GxF7Q8
    // eaWI70lsC5nTLGcbqgKu6gzkzHlHyHaE2FAQA/d5I2dvfsAYUQCza0Zdyw8mmTtHhlP2Tfxj1uPv
    // H4Q7BGuKnx3SWT2CnpbX4091w7KzLAztrbFBo/Tf9w8ZpgTK9k1ryfW9/xnk6rW6iQ==

    // Decrypt to restore back to the original:
    const sb_original = try chilkat.StringBuilder.init();
    defer sb_original.deinit();
    crypt.decryptSb(bd_encrypted, sb_original) catch {
        std.debug.print("{s}\n", .{try crypt.getLastErrorText(alloc)});
        return;
    };

    // Examine the original data:
    std.debug.print("{s}\n", .{try sb_original.getAsString(alloc)});

    // ----------------------------------------------------------------------------------
    // To do chacha20 encryption, just change the settings:

    crypt.setCryptAlgorithm("chacha20");
    crypt.setKeyLength(256);
    // The initial count is the initial block counter for the chacha20 algorithm.
    // It can be any integer, but must be set to the same when decrypting.
    crypt.setInitialCount(22);

    // EncryptSb completely replaces the contents of bdEncrypted.
    try crypt.encryptSb(sb, bd_encrypted);

    // However.. DecryptSb appends the decrypted text to whatever may
    // have already existed within sbOriginal.
    try crypt.decryptSb(bd_encrypted, sb_original);

    std.debug.print("----\n", .{});
    std.debug.print("The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt.\n", .{});
    std.debug.print("{s}\n", .{try sb_original.getAsString(alloc)});
    std.debug.print("Success.\n", .{});
}