DKNet.Svc.Encryption 10.0.27

DKNet.Svc.Encryption

Light‑weight .NET encryption & cryptographic utilities focused on pragmatic application scenarios:

• Symmetric encryption (AES-CBC wrapper and modern AES-GCM)
• Public key (RSA) encryption + signing
• HMAC (SHA-256 / SHA-512) with cached keyed instances
• Hashing (SHA-256 / SHA-512) with cached algorithm instances
• Password‑based encryption (PBKDF2 + AES-CBC)
• Base64 & Base64URL helpers (RFC 4648) with validation utilities
• Opinionated DI registration helper

✅ High test coverage (>97% lines) – designed to be easily auditable.

Contents

• Installation
• Quick Start
• Services & Interfaces
• Examples
  • AES (CBC wrapper)
  • AES-GCM (preferred)
  • Password-based Encryption
  • RSA Encrypt / Sign
  • HMAC
  • Hashing
  • Base64 / Base64URL
• Dependency Injection
• Security Notes
• Performance Notes
• Migration / Naming Notes
• Testing / Coverage
• Roadmap
• License

Installation

Add the NuGet package (placeholder ID – adjust to published package name):

dotnet add package DKNet.Svc.Encryption

Or reference the project directly in your solution.

Quick Start

var services = new ServiceCollection();
services.AddEncryptionServices();
var provider = services.BuildServiceProvider();

var aesGcm = provider.GetRequiredService<IAesGcmEncryption>();
var cipher = aesGcm.EncryptString("hello world");
var plain = aesGcm.DecryptString(cipher); // "hello world"

Services & Interfaces

Why “65”: Backward naming kept; includes both Base64 & Base64URL helpers.

Examples

AES (CBC wrapper)

using var aes = new AesEncryption(); // new key+iv generated
string key = aes.Key;                // Portable composite key (Base64(key):Base64(iv)) all Base64-wrapped
var cipher = aes.EncryptString("sensitive");
var back   = aes.DecryptString(cipher);

// Reconstruct with key
using var aes2 = new AesEncryption(key);
var again = aes2.DecryptString(cipher); // "sensitive"

Warning: IV is reused per instance → encryption is deterministic. Do not use this pattern for unique large scale messaging. Prefer IAesGcmEncryption.

AES-GCM (preferred)

using var gcm = new AesGcmEncryption();
string key = gcm.Key; // Base64 key only (no IV/nonce stored)
var cipher = gcm.EncryptString("hello");
var plain  = gcm.DecryptString(cipher);

// Associated Data (AAD)
var aad = Encoding.UTF8.GetBytes("meta");
var c2  = gcm.EncryptString("payload", aad);
var p2  = gcm.DecryptString(c2, aad);

Wrapper methods enforcing same key:

gcm.Encrypt("msg", gcm.Key); // OK
gcm.Decrypt(cipher, gcm.Key); // OK

Password-based Encryption

IPasswordAesEncryption pbe = new PasswordAesEncryption();
var password = "Sup3r$ecret";
var cipher = pbe.Encrypt("secret-config-json", password);
var json   = pbe.Decrypt(cipher, password);

Format: Base64( Base64(salt):Base64(iv):Base64(cipher) ).

RSA Encrypt / Sign

using var rsa = new RsaEncryption();
string publicKey  = rsa.PublicKey;            // Base64 (PKCS#1)
string privateKey = rsa.PrivateKey!;          // Keep secure

var cipher = rsa.Encrypt("api-key");
var clear  = rsa.Decrypt(cipher);

var sig = rsa.Sign("message");
var publicOnly = RsaEncryption.FromPublicKey(publicKey);
bool ok = publicOnly.Verify("message", sig); // true

HMAC

using IHmacHashing hmac = new HmacHashing();
var macBase64 = hmac.Compute("body", "shared-secret");
var macHex = hmac.Compute("body", "shared-secret", HmacAlgorithm.Sha512, asBase64:false);
var valid = hmac.Verify("body", "shared-secret", macBase64); // true

Hashing

using IShaHashing hash = new ShaHashing();
var sha256 = hash.ComputeHash("payload");           // Uppercase hex by default
var sha512Lower = hash.ComputeHash("payload", HashAlgorithmKind.Sha512, upperCase:false);
var ok = hash.VerifyHash("payload", sha256);

Base64 / Base64URL

var std = "hello".ToBase64String();        // SGVsbG8=
var plain = std.FromBase64String();        // hello

var url = "hello".ToBase64UrlString();     // SGVsbG8 (no '=')
var plain2 = url.FromBase64UrlString();    // hello

bool valid = std.IsBase64String();         // true

Dependency Injection

All cryptographic primitives are registered via the extension method:

services.AddEncryptionServices();

Resolves:

• IAesEncryption
• IAesGcmEncryption
• IShaHashing
• IHmacHashing
• IPasswordAesEncryption
• IRsaEncryption (generated keypair per singleton instance – for multi-key scenarios register factories yourself)

Registering IRsaEncryption as singleton generates one key pair at startup. Override if per-tenant / per-request keys are needed.

Security Notes

Key Handling

• Persist keys you want to reuse (e.g. AesGcmEncryption.Key or RSA private key).
• Protect RSA private keys with OS secrets vault, Azure Key Vault, AWS KMS, etc.
• Rotate keys periodically (design hook not included – compose externally).

Recommended Defaults

* Consider whether deterministic encryption is truly necessary.

Performance Notes

• Hash & HMAC services cache algorithm instances / keyed HMAC objects → fewer allocations under load.
• AES-GCM instance reused (keyed) – per-call ephemeral nonce & buffers.
• Avoid sharing a single AesEncryption instance across many threads if you later add per-call IV logic; current deterministic approach is thread-safe for reads due to ephemeral encryptors.

Migration / Naming Notes

Earlier internal drafts used names like HashGenerator / HmacGenerator; these evolved to ShaHashing / HmacHashing to signal narrow scope. If you had earlier package versions:

• Replace IHashGenerator → IShaHashing
• Replace IHmacGenerator → IHmacHashing
• AES-GCM wrapper methods (Encrypt/Decrypt with key parameter) now validate the key instead of silently using provided mismatched keys.

Testing / Coverage

Extensive xUnit + Shouldly tests cover:

• All happy paths + error paths (invalid keys, tampering, disposal)
• Base64 / Base64URL edge cases & Unicode
• Associated data success & mismatch (AES-GCM)
• DI registration

To run tests with coverage (using XPlat collector):

cd path/to/src
 dotnet test Services/DKNet.Svc.Encryption.Tests/DKNet.Svc.Encryption.Tests.csproj \
  --settings coverage.runsettings --collect:"XPlat Code Coverage"

Cobertura report (example): TestResults/<guid>/coverage.cobertura.xml.

Roadmap

License

Specify your license (e.g. MIT) here.

Disclaimer

This library streamlines common application crypto tasks but is not a substitute for a full security review. For high-risk / compliance contexts (PCI, HIPAA, FIPS) involve a qualified cryptographer and review threat models.

Contributing

PRs welcome. Please include:

• Unit tests for new branches
• XML docs for public members
• Justification for any new algorithms / modes

Support

Open an issue with reproduction steps. Security concerns: disclose privately first.

Enjoy building securely! 🔐