abdm_fidelius 0.1.0

Dart implementation of ABDM Fidelius encryption (ECDH + HKDF + AES-256-GCM) for India's health data exchange.

0.1.0

Initial release — full ABDM Fidelius encryption protocol in pure Dart.

Core Library

• ECDH key agreement on three curves: Weierstrass Curve25519 (ABDM default), X25519, P-256
• HKDF-SHA256 key derivation with 20-byte salt from nonce XOR
• AES-256-GCM authenticated encryption with 128-bit tag
• X.509 SubjectPublicKeyInfo DER encoding/decoding for all curves
• Strict base64 validation with descriptive error messages

High-Level API

• FideliusCurve25519 — Weierstrass Curve25519 (ABDM gateway compatible)
• FideliusX25519 — X25519 (RFC 7748 Montgomery form)
• FideliusP256 — P-256 / secp256r1 (NIST)
• Fully async API (Future<> on all methods)
• FideliusKeyPair with safe JSON serialization (excludes private key by default)
• FideliusEncryptedPayload with fidelius-cli compatible JSON format
• decrypt() returns null on GCM auth failure with optional onError callback

Low-Level Primitives

• generateKeyPair(), deriveSharedSecret(), xorAndSplitNonces()
• deriveKey(), aesGcmEncrypt(), aesGcmDecrypt()
• encodeX509SpkiDer(), decodeX509SpkiDer()

CLI Tool

• abdm_fidelius generate — key pair generation (all curves)
• abdm_fidelius encrypt — encrypt plaintext
• abdm_fidelius decrypt — decrypt payload
• JSON output, no JRE required

Interoperability

• Byte-for-byte compatible with Java fidelius-cli
• Field name mapping documented (senderPublicKey ↔ keyValue)

Testing

• 157+ unit and integration tests across all curves and engines
• Cross-curve isolation tests (ArgumentError and GCM failure paths)