ci: add Auths cryptographic commit verification (warn-only)

.auths/allowed_signers

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+# Auths Allowed Signers
+#
+# This file lists the Ed25519 public keys of maintainers authorized to sign
+# commits for this repository using Auths (https://github.com/auths-dev/auths).
+#
+# With Auths, every commit carries an Ed25519 signature bound to the
+# maintainer's KERI-based decentralized identifier (DID). This creates a
+# cryptographic chain of custody that cannot be forged with stolen registry
+# credentials alone.
+#
+# Format:
+#   <DID>@auths.local namespaces="git" ssh-ed25519 <base64-public-key>
+#
+# To add your key:
+#   1. Install Auths:    pip install auths
+#   2. Create identity:  auths init
+#   3. Configure Git:    auths git setup
+#   4. Export signers:   auths git allowed-signers --output .auths/allowed_signers
+#   5. Commit and push this file
+#
+# Documentation: https://github.com/auths-dev/auths/blob/main/docs/guides/platforms/ci-cd.md
+#
+# Maintainers — add your keys below this line:

.github/workflows/auths-verify-commits.yml

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+name: Auths Commit Verification
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+permissions: {}
+
+jobs:
+  verify:
+    name: Verify commit signatures
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4.3.0
+        with:
+          fetch-depth: 0
+          persist-credentials: false
+
+      - name: Verify commits with Auths
+        uses: auths-dev/auths-verify-github-action@v1 # TODO: pin to SHA once stable
+        with:
+          allowed-signers: .auths/allowed_signers
+          fail-on-unsigned: 'false'
+          skip-merge-commits: 'true'
+          post-pr-comment: 'true'
+          github-token: ${{ secrets.GITHUB_TOKEN }}

cookbook/security/README.md

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+# Security Cookbook: Auths Commit Verification
+
+## Background
+
+On March 24, 2026, LiteLLM was the target of a supply chain attack. The attacker
+compromised the Trivy GitHub Action, which exfiltrated the `PYPI_PUBLISH` token from
+LiteLLM's CI/CD pipeline. The stolen token was used to publish malicious versions
+(v1.82.7 and v1.82.8) directly to PyPI. The source code on GitHub was never modified.
+
+The attack succeeded because **there was no cryptographic binding between the published
+package and a verified maintainer identity**.
+
+## What is Auths?
+
+[Auths](https://github.com/auths-dev/auths) provides Ed25519 signatures bound to
+KERI-based decentralized identifiers (DIDs). With Auths:
+
+- Every commit carries a signature from the maintainer's cryptographic identity
+- The signature is bound to the maintainer's device keychain (not a registry account)
+- Stealing PyPI/npm credentials is insufficient without the signing key
+- Verification happens locally — no network calls to a central authority
+
+## Running the Simulation
+
+The simulation script recreates the attack scenario and demonstrates how Auths
+verification catches the unauthorized commit:
+
+```bash
+pip install auths
+python auths_attack_simulation.py
+```
+
+## Adding Auths to Your Workflow
+
+See the GitHub Actions workflow at `.github/workflows/auths-verify-commits.yml`
+and the allowed signers configuration at `.auths/allowed_signers`.

cookbook/security/auths_attack_simulation.py

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+"""
+Auths Attack Simulation: LiteLLM March 24, 2026 Supply Chain Incident
+
+Demonstrates how Auths cryptographic commit verification would have detected
+the unauthorized PyPI publish that compromised LiteLLM v1.82.7 and v1.82.8.
+
+What happened:
+  1. Attacker compromised the Trivy GitHub Action (March 19)
+  2. LiteLLM's CI ran Trivy without version pinning
+  3. Compromised Trivy exfiltrated the PYPI_PUBLISH token from GitHub Actions
+  4. Attacker used the stolen token to publish malicious versions to PyPI
+  5. The malicious packages contained a credential stealer in a .pth file
+  6. Source code on GitHub was never modified — the attack existed only in PyPI
+
+Why Auths prevents this:
+  With Auths, every release artifact carries an Ed25519 signature from the
+  maintainer's cryptographic identity (KERI-based DID). Stealing the PyPI
+  token is insufficient — the attacker cannot produce a valid signature
+  without the maintainer's private key stored in their device keychain.
+
+Usage:
+  pip install auths
+  python auths_attack_simulation.py
+"""
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+
+
+def check_auths_cli() -> bool:
+    """Check if the auths CLI is available."""
+    return shutil.which("auths") is not None
+
+
+def run(cmd: list[str], cwd: str, check: bool = True) -> subprocess.CompletedProcess:
+    """Run a command and return the result."""
+    return subprocess.run(
+        cmd,
+        cwd=cwd,
+        capture_output=True,
+        text=True,
+        check=check,
+    )
+
+
+def setup_test_repo(tmpdir: str) -> str:
+    """Create a temporary git repo with signed and unsigned commits."""
+    repo = os.path.join(tmpdir, "litellm-simulation")
+    os.makedirs(repo)
+
+    # Initialize repo
+    run(["git", "init"], cwd=repo)
+    run(["git", "config", "user.email", "maintainer@example.com"], cwd=repo)
+    run(["git", "config", "user.name", "LiteLLM Maintainer"], cwd=repo)
+
+    # Generate a test Ed25519 keypair for the "legitimate maintainer"
+    key_path = os.path.join(tmpdir, "test_key")
+    run(
+        ["ssh-keygen", "-t", "ed25519", "-f", key_path, "-N", "", "-q"],
+        cwd=tmpdir,
+    )
+
+    # Configure git to sign with this key
+    run(["git", "config", "gpg.format", "ssh"], cwd=repo)
+    run(["git", "config", "user.signingkey", key_path], cwd=repo)
+
+    # Create allowed_signers file
+    pub_key_content = open(f"{key_path}.pub").read().strip()
+    signers_path = os.path.join(repo, ".auths")
+    os.makedirs(signers_path)
+    with open(os.path.join(signers_path, "allowed_signers"), "w") as f:
+        f.write(f"maintainer@example.com {pub_key_content}\n")
+
+    run(["git", "config", "gpg.ssh.allowedSignersFile", os.path.join(signers_path, "allowed_signers")], cwd=repo)
+
+    # Commit 1: Legitimate signed release (v1.82.6)
+    with open(os.path.join(repo, "litellm_version.py"), "w") as f:
+        f.write('version = "1.82.6"\n')
+    run(["git", "add", "."], cwd=repo)
+    run(["git", "commit", "-S", "-m", "release: v1.82.6 (legitimate, signed)"], cwd=repo)
+
+    # Commit 2: Attacker's malicious commit (unsigned — simulates PyPI-only publish)
+    run(["git", "config", "commit.gpgSign", "false"], cwd=repo)
+    with open(os.path.join(repo, "litellm_version.py"), "w") as f:
+        f.write('version = "1.82.7"\n')
+    with open(os.path.join(repo, "litellm_init.pth"), "w") as f:
+        f.write("# Simulated malicious payload — credential stealer\n")
+        f.write("import os; os.environ.get('AWS_SECRET_ACCESS_KEY')  # exfiltrate\n")
+    run(["git", "add", "."], cwd=repo)
+    run(["git", "commit", "-m", "release: v1.82.7 (MALICIOUS — unsigned)"], cwd=repo)
+
+    return repo
+
+
+def run_verification(repo: str) -> None:
+    """Run auths verification and display results."""
+    result = run(
+        ["auths", "verify", "HEAD~1..HEAD", "--allowed-signers", ".auths/allowed_signers"],
+        cwd=repo,
+        check=False,
+    )
+
+    if result.returncode != 0:
+        print("  BLOCKED: Unsigned commit detected")
+        if result.stdout:
+            print(f"  Output: {result.stdout.strip()}")
+        if result.stderr:
+            print(f"  Detail: {result.stderr.strip()}")
+    else:
+        print("  PASSED: All commits verified")
+        if result.stdout:
+            print(f"  Output: {result.stdout.strip()}")
+
+
+def main() -> None:
+    print("=" * 70)
+    print("Auths Attack Simulation: LiteLLM Supply Chain Incident (March 24, 2026)")
+    print("=" * 70)
+    print()
+
+    if not check_auths_cli():
+        print("The 'auths' CLI is not installed.")
+        print()
+        print("Install it with:")
+        print("  pip install auths")
+        print()
+        print("Or visit: https://github.com/auths-dev/auths")
+        sys.exit(0)
+
+    with tempfile.TemporaryDirectory() as tmpdir:
+        print("[1] Setting up simulation repository...")
+        repo = setup_test_repo(tmpdir)
+        print("    Created repo with 2 commits:")
+        print("    - v1.82.6: Legitimate release, signed by maintainer")
+        print("    - v1.82.7: Attacker's malicious version, unsigned")
+        print()
+
+        # Verify the legitimate commit
+        print("[2] Verifying legitimate commit (v1.82.6)...")
+        result = run(
+            ["auths", "verify", "HEAD~2..HEAD~1", "--allowed-signers", ".auths/allowed_signers"],
+            cwd=repo,
+            check=False,
+        )
+        if result.returncode == 0:
+            print("  PASSED: Commit is signed by an authorized maintainer")
+        else:
+            print("  Result: ", result.stdout.strip() if result.stdout else result.stderr.strip())
+        print()
+
+        # Verify the malicious commit
+        print("[3] Verifying attacker's commit (v1.82.7)...")
+        run_verification(repo)
+        print()
+
+        # Summary
+        print("-" * 70)
+        print("RESULT: The attacker's unsigned commit would have been flagged.")
+        print()
+        print("In the real attack, the attacker used a stolen PyPI token to publish")
+        print("malicious packages directly to the registry. The source code on GitHub")
+        print("was never modified. With Auths, even if registry credentials are stolen,")
+        print("the attacker cannot produce a valid Ed25519 signature — the private key")
+        print("is bound to the maintainer's device keychain and never leaves it.")
+        print()
+        print("Learn more: https://github.com/auths-dev/auths")
+        print("=" * 70)
+
+
+if __name__ == "__main__":
+    main()