dCypher: Quantum-Resistant Proxy Recryption System

Status: 🚀 Implementation Phase
Version: 2.0 (Rust)

Overview

dCypher is a production-ready proxy recryption system enabling secure, revocable file sharing with untrusted storage providers. Built on lattice-based cryptography (OpenFHE) with post-quantum signatures (liboqs), it provides end-to-end encryption where files can be shared without exposing private keys or plaintext.

Core Innovation

Proxy Recryption: Transform ciphertext encrypted for Alice into ciphertext for Bob without ever decrypting. The storage provider facilitates sharing without accessing plaintext.

Hybrid Encryption: KEM-DEM architecture with pluggable PRE backends (lattice for post-quantum, EC for classical). Symmetric encryption (XChaCha20 + Bao) handles bulk data.

Self-Correcting Identifiers: HDprint provides human-readable identifiers that automatically correct typos and restore proper case from lowercase input.

Current Status

✅ Phase 0: Planning — COMPLETE

Implementation plan (docs/IMPLEMENTATION_PLAN.md)
All design decisions documented
Workspace structure defined

🔲 Implementation Phases

Phase	Description	Status
1	FFI Bindings (OpenFHE + liboqs)	🔲
2	Core Cryptography (PRE traits, hybrid encryption)	🔲
3	Protocol Layer (Protobuf, Bao)	🔲
4	Storage Client (S3-compatible)	🔲
4b	Auth Service (identikey-storage-auth)	🔲
5	HDprint (parallelizable)	🔲
6	Recryption Proxy Server	🔲
7	CLI Application	🔲
8	Minimal TUI	🔲

Timeline: 10-12 weeks to production-ready

Repository Structure

dcypher/
├── README.md
├── docs/
│   ├── IMPLEMENTATION_PLAN.md    # 📋 Master plan - READ THIS FIRST
│   ├── hybrid-encryption-architecture.md
│   ├── pre-backend-traits.md
│   ├── storage-design.md
│   ├── wire-protocol.md
│   └── ...                       # Other design docs
│
├── python-prototype/             # 📦 ARCHIVED: Reference implementation
│   ├── src/dcypher/
│   ├── tests/
│   └── docs/
│
├── vendor/                       # Third-party dependencies
│   ├── openfhe-development/
│   ├── liboqs/
│   └── ...
│
└── [Rust workspace - Phase 1+]
    ├── crates/
    │   ├── dcypher-ffi/
    │   ├── dcypher-core/
    │   ├── dcypher-proto/
    │   ├── dcypher-storage/
    │   └── dcypher-hdprint/
    ├── dcypher-cli/
    ├── dcypher-server/
    ├── dcypher-tui/
    └── identikey-storage-auth/

Quick Start (Coming Soon)

# Phase 1+: Build from source
cargo build --release

# Generate identity
dcypher identity new --output alice.json

# Encrypt file
dcypher encrypt myfile.txt --for <bob-pubkey> --output myfile.enc

# Share with Bob (generates recryption key)
dcypher share create <file-hash> --to <bob-pubkey>

# Bob downloads (server recrypts on-the-fly)
dcypher share download <share-id> --output myfile.txt

Key Features

🔐 Cryptography

OpenFHE BFVrns for lattice-based proxy recryption
ED25519 for classical signatures
ML-DSA-87 (mandatory) + optional PQ algorithms
Multi-signature authorization (all keys must sign)

💾 Storage

S3-compatible storage layer (Minio for dev, any S3 for prod)
Authenticated access via file hash lookup
Chunked streaming for large files
Content-addressed storage

🎯 HDprint Identifiers

Error correction: Automatically fixes single-character typos
Case restoration: Type lowercase, get proper mixed-case
Hierarchical scaling: 17.6 to 158+ bits security
Human-friendly: Base58 encoding, visual separators

🌐 API & Interfaces

HTTP REST API (Axum framework)
CLI application with rich interactions
Minimal TUI for visual operations

Design Philosophy

Key Decisions

Area	Decision
Encryption	Hybrid KEM-DEM with pluggable PRE backends
Hashing	Blake3 everywhere (HMAC-SHA3-512 for HDprint only)
Verification	Blake3/Bao tree mode for streaming
Wire format	Protobuf (primary), ASCII armor (export)
Storage	Content-addressed S3 + auth service
Signatures	ED25519 (classical) + ML-DSA-87 (post-quantum)

Changes from Python Prototype

Removed	Added
ECDSA/SECP256k1	Pluggable PRE backends (lattice + EC)
Naive file storage	S3-compatible + auth service
Custom Merkle trees	Blake3/Bao streaming verification
Mixed hashing	Blake3 standardized

Clean Slate: No compatibility with Python prototype (different serialization, no production deployments)

Documentation

docs/IMPLEMENTATION_PLAN.md - Master implementation plan
python-prototype/docs/ - Original specifications (archived)

Design Documents

Document	Description
`docs/hybrid-encryption-architecture.md`	KEM-DEM with pluggable PRE backends
`docs/pre-backend-traits.md`	`PreBackend` trait hierarchy
`docs/storage-design.md`	S3 + auth service architecture
`docs/wire-protocol.md`	Protobuf + ASCII armor formats
`docs/verification-architecture.md`	Blake3/Bao streaming verification
`docs/hashing-standard.md`	Blake3 standardization
`docs/non-determinism.md`	Crypto testing strategy
`docs/hdprint-specification.md`	HDprint identifier system
`docs/hmac-analysis.md`	HMAC usage (HDprint only)

Development

Prerequisites

Rust 1.75+ (stable)
OpenFHE C++ library
liboqs (post-quantum crypto)
Docker (for Minio development environment)

Python Prototype (Archived)

The original Python proof-of-concept is preserved in python-prototype/ for reference. It demonstrated the feasibility of proxy recryption with post-quantum signatures and includes a full TUI implementation.

To explore the prototype:

cd python-prototype
# See python-prototype/README.md for setup instructions

Note: The Python implementation is archived and not actively maintained. All new development is in Rust.

Terminology

Recryption: Transformation of ciphertext from one key to another (not "re-encryption")
Recryption Key: The key that enables recryption transformation (not "rekey" or "re-encryption key")
Recrypted: Data that has undergone recryption transformation

This terminology is standardized throughout the Rust implementation.

Architecture Highlights

Crates

Crate	Purpose
`dcypher-ffi`	OpenFHE + liboqs FFI bindings
`dcypher-core`	PRE backends, hybrid encryption, signatures
`dcypher-proto`	Wire protocol (Protobuf + Bao)
`dcypher-storage`	S3-compatible storage client
`dcypher-hdprint`	Self-correcting identifiers
`identikey-storage-auth`	Auth service for storage access

Binaries

Binary	Purpose
`dcypher-server`	Recryption proxy (streams KEM ciphertext, holds recrypt keys)
`dcypher-cli`	Command-line interface
`dcypher-tui`	Minimal terminal UI

Security Model

Trust Assumptions

Component	Trust Level	Notes
Storage provider	Untrusted	Sees only ciphertext + wrapped keys
Recryption proxy	Semi-trusted	Has recrypt keys, not secret keys; self-hostable
Auth service	Trusted	Controls access; can be self-hosted
Client	Trusted	Holds secret keys

Cryptographic Guarantees

E2E Encryption: Only key holders decrypt (plaintext never leaves client)
Quantum Resistance: Lattice-based PRE + ML-DSA-87 signatures
Forward Secrecy: Per-file random symmetric keys
Streaming Integrity: Blake3/Bao verification during download

Contributing

See docs/IMPLEMENTATION_PLAN.md for current phase and open tasks.

License

[License TBD]

Links

Website: identikey.io/recryption

→ docs/IMPLEMENTATION_PLAN.md for full implementation details

Name		Name	Last commit message	Last commit date
Latest commit History 398 Commits
.cargo		.cargo
.claude		.claude
crates		crates
dcypher-server		dcypher-server
docker		docker
docs		docs
python-prototype		python-prototype
thoughts/handoffs/general		thoughts/handoffs/general
vendor		vendor
.dockerignore		.dockerignore
.gitignore		.gitignore
.gitmodules		.gitmodules
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
Justfile		Justfile
README.md		README.md

identikey/dcypher

Folders and files

Latest commit

History

Repository files navigation