modelsign

Sign AI models with identity. Verify anywhere. Part of the AURE Provenance stack by Constant Systems.

modelsign cryptographically binds model files to a signed identity card — who made this model, what it's based on, what it claims to be. Ed25519 signatures, zero ML dependencies, works with any model format.

Note:modelsign is distinct from the OpenSSF model-signing package on PyPI. We are an independent implementation using Ed25519 + RFC 8785 canonical JSON. Designed and maintained by James Kerr / Constant Systems.

Install

pip install modelsign

Quick Start

# Generate your signing key
modelsign keygen
# Sign a model with a name
modelsign sign model.safetensors --name "My-Llama-8B-v1"# Verify it
modelsign verify model.safetensors
# Inspect the identity card
modelsign inspect model.safetensors.sig

Rich Identity Cards

Sign with full provenance:

# Create an identity card
cat > card.json << 'EOF'{ "name": "Llama-3.1-8B-Chat-QJ", "architecture": "LlamaForCausalLM", "base_model": "meta-llama/Llama-3.1-8B-Instruct", "version": "1.0.0", "creator": "ConstantQJ", "license": "Llama 3.1 Community", "intended_use": "Chat assistant", "training": { "dataset": "custom-chat-v2", "epochs": 3, "hardware": "DGX Spark GB10" }, "eval_metrics": { "mmlu": 0.68, "humaneval": 0.53 }}EOF
modelsign sign model.safetensors --identity card.json

Python SDK

frommodelsignimport (
ModelCard, validate_card, canonical_json,
generate_keypair, load_private_key, load_public_key,
sign_bytes, build_file_message, verify_bytes,
hash_file, SigFile, write_sig, read_sig,
)

What It Protects Against

• Post-signing tampering of model weights
• Substitution of one model for another
• Metadata swap (changing identity claims invalidates signature)

What It Does NOT Cover

• Key compromise (your key, your responsibility)
• Model safety, fairness, or legal compliance
• Cryptographic timestamping (timestamps are metadata, not proofs)

How It Compares

	modelsign	OpenSSF Model Signing (OMS)
Focus	Simple signing + rich identity	Supply-chain integrity via Sigstore
Identity card	Embedded (architecture, training, eval metrics)	Minimal (being expanded)
Setup	pip install modelsign	Sigstore toolchain + transparency log
Signing	Offline, Ed25519, one command	Keyless via OIDC + Rekor transparency
Best for	Individual fine-tunes, HF uploads, quick sharing	Enterprise supply-chain, NGC publishing
Network required	No	Yes (Sigstore/Rekor)

modelsign and OMS are complementary. Use modelsign for fast, offline, identity-rich signing. Use OMS when you need transparency logs and keyless verification at enterprise scale.

Identity Card Schema

Field	Required	Description
name	Yes	Model name
architecture	No	Model class (e.g., LlamaForCausalLM)
base_model	No	Parent model name/path
parent_signature	No	Hash of parent's .sig (provenance chain)
version	No	Semantic version
creator	No	Person or organization
license	No	SPDX identifier or name
intended_use	No	What the model is for
restrictions	No	What it should NOT be used for
training	No	{dataset, dataset_hash, epochs, hardware}
quantization	No	Method (e.g., GPTQ-4bit)
eval_metrics	No	Benchmark results ({mmlu: 0.68})
extra	No	Any additional metadata

License

Apache 2.0 — QJ / ConstantOne (CIP1 LLC)