protect-mcp-setup

name protect-mcp-setup description Configure Cedar policy enforcement and Ed25519 signed receipts for Claude Code tool calls. Use when setting up projects that need cryptographic audit trails, policy-gated tool execution, or compliance-ready evidence of agent actions. protect-mcp — Policy Enforcement + Signed Receipts Cryptographic governance for every Claude Code tool call. Each invocation is evaluated against a Cedar policy and produces an Ed25519-signed receipt that anyone can verify offline. Overview Claude Code runs powerful tools: Bash , Edit , Write , WebFetch . By default there is no audit trail, no policy enforcement, and no way to prove what was decided after the fact. protect-mcp closes all three gaps: Cedar policies (AWS's open authorization engine) evaluate every tool call before execution. Cedar deny is authoritative. Ed25519 receipts record each decision with its inputs, the policy that governed it, and the outcome. Receipts are hash-chained. Offline verification via npx @veritasacta/verify . No server, no account, no trust in the operator. Problem AI agents make decisions that affect money, safety, and rights. The Claude Code session log records what happened, but the log is: Mutable — anyone with access can edit it Unsigned — there is no way to prove integrity Operator-bound — verification requires trusting whoever holds the log For compliance contexts (finance, healthcare, regulated research), this is not sufficient. You need tamper-evident evidence that can be verified by third parties without trusting you. Solution Add protect-mcp to your Claude Code project: # 1. Install the plugin (adds hooks + skill to your project) claude plugin install wshobson/agents/protect-mcp # 2. Configure hooks in .claude/settings.json (see below) # 3. Start the receipt-signing server (runs locally, no external calls) npx protect-mcp@latest serve --enforce # 4. Use Claude Code normally. Every tool call is now policy-evaluated # and produces a signed receipt in ./receipts/ Hook Configuration Add the following to your project's .claude/settings.json : { "hooks" : { "PreToolUse" : [ { "matcher" : ".*" , "hook" : { "type" : "command" , "command" : "npx protect-mcp@latest evaluate --policy ./protect.cedar --tool \"$TOOL_NAME\" --input \"$TOOL_INPUT\" || exit 2" } } ] , "PostToolUse" : [ { "matcher" : ".*" , "hook" : { "type" : "command" , "command" : "npx protect-mcp@latest sign --tool \"$TOOL_NAME\" --input \"$TOOL_INPUT\" --output \"$TOOL_OUTPUT\" --receipts ./receipts/" } } ] } } What each hook does PreToolUse — Runs BEFORE the tool executes. Evaluates the tool call against your Cedar policy file. If Cedar returns deny , the hook exits with code 2 and Claude Code blocks the tool call entirely. PostToolUse — Runs AFTER the tool completes. Signs a receipt containing the tool name, input hash, output hash, decision, policy digest, and timestamp. Writes the receipt to ./receipts/<timestamp>.json . Cedar Policy File Create ./protect.cedar at the project root: // Allow read-only tools by default permit ( principal, action in [Action::"Read", Action::"Glob", Action::"Grep", Action::"WebFetch"], resource ); // Require explicit allow for destructive tools permit ( principal, action == Action::"Bash", resource ) when { // Allow safe commands only context.command_pattern in ["git", "npm", "ls", "cat", "echo", "pwd", "test"] }; // Never allow recursive deletion forbid ( principal, action == Action::"Bash", resource ) when { context.command_pattern == "rm -rf" }; // Require confirmation for writes outside the project forbid ( principal, action in [Action::"Edit", Action::"Write"], resource ) when { context.path_starts_with != "." }; Verification Verify a single receipt: npx @veritasacta/verify receipts/2026-04-15T10-30-00Z.json # Exit 0 = valid # Exit 1 = tampered # Exit 2 = malformed Verify the entire chain: npx @veritasacta/verify receipts/*.json Use the plugin's slash commands from within Claude Code: /verify-receipt receipts/latest.json /audit-chain ./receipts/ --last 20 Receipt Format Each receipt is a JSON file with this structure: { "receipt_id" : "rec_8f92a3b1" , "receipt_version" : "1.0" , "issuer_id" : "claude-code-protect-mcp" , "event_time" : "2026-04-15T10:30:00.000Z" , "tool_name" : "Bash" , "input_hash" : "sha256:a3f8..." , "decision" : "allow" , "policy_id" : "autoresearch-safe" , "policy_digest" : "sha256:b7e2..." , "parent_receipt_id" : "rec_3d1ab7c2" , "public_key" : "4437ca56815c0516..." , "signature" : "4cde814b7889e987..." } Ed25519 signatures (RFC 8032) JCS canonicalization (RFC 8785) before signing Hash-chained to the previous receipt via parent_receipt_id Offline verifiable — no network call, no vendor lookup Why This Matters Before After "Trust me, the agent only read files" Cryptographically provable: every Read logged and signed "The log shows it happened" The receipt proves it happened, and no one can edit it "You'd have to audit our system" Anyone can verify every receipt offline "Logs might be different by now" Ed25519 signatures lock the record at signing time Standards Ed25519 — RFC 8032 (digital signatures) JCS — RFC 8785 (deterministic JSON canonicalization) Cedar — AWS's open authorization policy language IETF draft — draft-farley-acta-signed-receipts Related npm : protect-mcp Verify CLI : @veritasacta/verify Source : github.com/ScopeBlind/scopeblind-gateway Protocol : veritasacta.com Integrations : Microsoft Agent Governance Toolkit (PR #667), AWS cedar-policy/cedar-for-agents (PR #64)