Cyphera

Data protection SDK for .NET — format-preserving encryption (FF1/FF3), data masking, and hashing.

dotnet add package Cyphera

Usage

using Cyphera;

// Auto-discover: checks CYPHERA_CONFIG_FILE env, ./cyphera.json, /etc/cyphera/cyphera.json
var c = Cyphera.Load();

// Or load from a specific file
var c = Cyphera.FromFile("./config/cyphera.json");

// Or inline config
var json = JsonDocument.Parse(@"{
  ""configurations"": {
    ""ssn"": { ""engine"": ""ff1"", ""key_ref"": ""my-key"", ""header"": ""T01"" }
  },
  ""keys"": {
    ""my-key"": { ""material"": ""2B7E151628AED2A6ABF7158809CF4F3C"" }
  }
}");
var c = Cyphera.FromConfig(json.RootElement);

// Protect
var encrypted = c.Protect("123-45-6789", "ssn");
// → "T01i6J-xF-07pX" (DPH-prefixed, dashes preserved)

// Access — the SDK uses the header to figure out the configuration
var decrypted = c.Access(encrypted);
// → "123-45-6789"

Engines

Engine	Reversible	Description
ff1	Yes	NIST SP 800-38G FF1 format-preserving encryption
ff3	Yes	NIST SP 800-38G Rev 1 FF3-1 format-preserving encryption
mask	No	Simple pattern masking (last4, first1, full, etc.)
hash	No	SHA-256/384/512, HMAC when key provided

Configuration File (cyphera.json)

{
  "configurations": {
    "ssn": { "engine": "ff1", "key_ref": "my-key", "header": "T01" },
    "cc": { "engine": "ff1", "key_ref": "my-key", "header": "T02" },
    "ssn_mask": { "engine": "mask", "pattern": "last4", "header_enabled": false }
  },
  "keys": {
    "my-key": { "material": "2B7E151628AED2A6ABF7158809CF4F3C" }
  }
}

The header (Data Protection Header, DPH) is a short prefix prepended to protected output that identifies the configuration used. It lets Access() reverse a value without the caller naming the configuration.

Cross-Language Compatible

All SDKs produce identical output for the same inputs:

Input:       123-45-6789
Java:        T01i6J-xF-07pX
Rust:        T01i6J-xF-07pX
Node:        T01i6J-xF-07pX
Python:      T01i6J-xF-07pX
Go:          T01i6J-xF-07pX
.NET:        T01i6J-xF-07pX

Status

Alpha. API is unstable. Cross-language test vectors validated against Java, Rust, Node, Python, and Go implementations.

License

Apache 2.0 — Copyright 2026 Horizon Digital Engineering LLC