Eigenverft.NetLib.Transformations 1.0.0.5-g17613f8942

Eigenverft.NetLib.Transformations

Compose reusable reversible string transformations, from simple representations and obfuscation to password-based AES-GCM and machine-scoped protection.

✨ At a glance

The package also references Eigenverft.NetLib.Security.MachineBinding for the machine-bound transform. For self-describing persisted configuration values, use Eigenverft.NetLib.Configuration.Values.

📦 Installation

dotnet add package Eigenverft.NetLib.Transformations

🚀 Quick start

Compose transforms in forward order. This example changes representation; it does not encrypt the text. For persisted configuration values that need a self-describing codec, see Configuration.Values; raw transforms do not frame values or choose configuration keys.

using System;
using System.IO;
using Eigenverft.NetLib.Transformations;

ReversibleStringTransform pipeline = ReversibleStringTransforms.Compose(
    ReversibleStringTransforms.Rot13,
    ReversibleStringTransforms.Base64);

string payload = pipeline.Apply("Hello");
if (!pipeline.TryReverse(payload, out string original))
{
    throw new InvalidDataException("The payload could not be reversed.");
}

Console.WriteLine(original);

Compose(...) applies first-to-last and reverses last-to-first. TryReverse(...) returns false and the original transformed value if any stage fails; no partial reversal is returned.

🔁 Available transforms and behavior

ReversibleStringTransforms provides Base64, Base92JsonSafe, Rot13, Caesar(shift), DpapiMachine, DpapiMachineBase64Url, AesPassword(password), AesPassword(passwordAsciiBytes), PhysicalMachineBoundAes(), and Compose(...). You can also construct a ReversibleStringTransform with custom apply/reverse delegates.

Transforms operate on string values only. They do not add persisted enc: wrappers, identify the transform during reversal, select configuration keys, or migrate stored values. For persisted configuration, Configuration.Values supplies self-describing codecs on top of these transforms.

🔐 Security and platform notes

• Base64 and Base92 are representations; ROT13 and Caesar are reversible obfuscation. None provides confidentiality.
• Base92JsonSafe avoids JSON-string escaping, but is not HTML/XML escaping; its alphabet includes characters such as <, >, &, apostrophe, and slash.
• AesPassword(...) uses AES-GCM with a password-derived key. Security depends on how the application obtains and protects the password. The transform retains the password for its lifetime; embedding it in an application is not a secrecy boundary. The byte-array overload only makes simple static inspection less direct.
• DpapiMachine and DpapiMachineBase64Url require Windows DPAPI LocalMachine and throw PlatformNotSupportedException on other platforms. They bind to the machine, not to a user or administrator boundary; another user on that Windows machine may unprotect the value.
• PhysicalMachineBoundAes() derives its password material from a platform fingerprint. It is lightweight resistance to copying application files to another machine, not a hardware-backed secret; source-machine access can reproduce the fingerprint.

🎯 Target frameworks

• net8.0
• net10.0

A .NET 9 consumer can use the compatible net8.0 asset.

🔗 Project links

• Source project
• Solution guide
• Configuration.Values package
• MachineBinding source project
• Repository

📄 License

MIT License