moss-sdk 0.3.0

Cryptographic identity and signed outputs for AI agents

MOSS

Unsigned agent output is broken output.

MOSS (Message-Origin Signing System) provides cryptographic signing for AI agents. Every output is signed with ML-DSA-44 (post-quantum), creating non-repudiable execution records with audit-grade provenance.

Install

pip install moss-sdk

Quick Start

from moss import sign, verify

# Sign any agent output
result = sign(
    output={"action": "transfer", "amount": 500},
    agent_id="agent-finance-01",
    context={"user_id": "u123"}
)

# result.envelope: MOSS Envelope with signature
# result.signature: ML-DSA-44 post-quantum signature
# result.allowed: True (or False if enterprise policy blocks)

# Verify offline - no MOSS servers required
verify_result = verify(result.envelope)
if verify_result.valid:
    print(f"Signed by: {verify_result.subject}")

Enterprise Mode

Set MOSS_API_KEY to enable enterprise features:

import os
os.environ["MOSS_API_KEY"] = "your-api-key"

from moss import sign, enterprise_enabled

# Check if enterprise mode is active
print(f"Enterprise: {enterprise_enabled()}")  # True

# Sign with automatic policy evaluation
result = sign(
    output={"action": "high_risk_transfer", "amount": 1000000},
    agent_id="finance-bot",
    action="transfer",
    context={"user_id": "u123", "department": "finance"}
)

if result.blocked:
    print(f"Action blocked: {result.policy.reason}")
else:
    print(f"Action allowed, evidence_id: {result.evidence_id}")

Execution Record Format

Every signed action produces a verifiable execution record:

agent_id:      moss:agent:agent-finance-01
action:        transfer
timestamp:     2026-01-18T12:34:56Z
sequence:      42
payload_hash:  SHA-256:abc123...
signature:     ML-DSA-44:xyz789...
status:        VERIFIED

Using Subject (Advanced)

from moss import Subject

agent = Subject.create("moss:dev:my-agent")
envelope = agent.sign({"action": "approved", "amount": 500})

result = Subject.verify(envelope)
assert result.valid

TypeScript SDK

npm install @moss/sdk

import { sign, verify } from '@moss/sdk';

const envelope = await sign({
  output: agentResponse,
  agentId: "agent-finance-01"
});

const result = await envelope.verify();

Framework Integrations

Package	Framework	Install
moss-langchain	LangChain	pip install moss-langchain
moss-langgraph	LangGraph	pip install moss-langgraph
moss-crewai	CrewAI	pip install moss-crewai
moss-autogen	AutoGen	pip install moss-autogen
moss-openai	OpenAI SDK	pip install moss-openai
moss-anthropic	Anthropic SDK	pip install moss-anthropic
moss-google	Google GenAI	pip install moss-google

CLI

moss subject create moss:dev:my-agent
echo '{"action": "test"}' | moss sign moss:dev:my-agent - > envelope.json
moss verify payload.json envelope.json

What MOSS Provides

Capability	Description
Mandatory Signing	Every agent action is signed
Offline Verification	Verify without network access
Post-Quantum Security	ML-DSA-44 (FIPS 204)
Provenance	Non-repudiable execution history

What MOSS Does NOT Provide (Free Tier)

Limitation	Solution
Long-term retention	Upgrade to Evidence tier
Audit exports	Upgrade to Evidence tier
Evidence continuity	Upgrade to Defensible tier

Production environments require retained, verifiable execution records.
Free tier provides runtime enforcement. See mosscomputing.com for evidence continuity options.

Protocol

MOSS implements moss-0001. See SPEC.md.

Envelope

{
  "spec": "moss-0001",
  "version": 1,
  "alg": "ML-DSA-44",
  "subject": "moss:acme:order-bot",
  "key_version": 1,
  "seq": 42,
  "issued_at": 1733200000,
  "payload_hash": "<base64url(SHA-256(canonical(payload)))>",
  "signature": "<base64url(ML-DSA-44 signature)>"
}

Verification

1. Check spec == "moss-0001"
2. Compute hash = base64url(SHA-256(canonical(payload)))
3. Assert hash == envelope.payload_hash
4. Resolve (subject, key_version) → public_key
5. Verify ML-DSA-44.verify(public_key, canonical(signed_bytes), signature)

Cryptography

Signatures	ML-DSA-44 (FIPS 204)
Hash	SHA-256
Encoding	base64url, no padding
Canonicalization	RFC 8785
Key storage	AES-256-GCM + Scrypt

Keys stored at ~/.moss/keys/. Set MOSS_KEY_PASSPHRASE to encrypt at rest.

Links

• mosscomputing.com — Project site
• app.mosscomputing.com — Dashboard
• SPEC.md — Protocol specification
• PyPI — Package

Contributing

See CONTRIBUTING.md.

Security

Report vulnerabilities to [e-mail]. See SECURITY.md.

License

Proprietary - See LICENSE for terms.