@kya-os/agentshield-nextjs/dist/signature-verifier.mjs.map

Next.js middleware for AgentShield AI agent detection

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* Ed25519 Signature Verification for HTTP Message Signatures\n * Implements proper cryptographic verification for ChatGPT and other agents\n * \n * Based on RFC 9421 (HTTP Message Signatures) and ChatGPT's implementation\n * Reference: https://help.openai.com/en/articles/9785974-chatgpt-user-allowlisting\n */\n\n/**\n * Known public keys for AI agents\n */\nconst KNOWN_KEYS = {\n  chatgpt: [\n    {\n      kid: 'otMqcjr17mGyruktGvJU8oojQTSMHlVm7uO-lrcqbdg',\n      // ChatGPT's current Ed25519 public key (base64)\n      publicKey: '7F_3jDlxaquwh291MiACkcS3Opq88NksyHiakzS-Y1g',\n      validFrom: new Date('2025-01-01').getTime() / 1000,\n      validUntil: new Date('2025-04-11').getTime() / 1000,\n    },\n  ],\n};\n\n/**\n * Parse the Signature-Input header according to RFC 9421\n */\nfunction parseSignatureInput(signatureInput: string): {\n  keyid: string;\n  created?: number | undefined;\n  expires?: number | undefined;\n  signedHeaders: string[];\n} | null {\n  try {\n    // Example: sig1=(\"@method\" \"@path\" \"@authority\" \"date\");keyid=\"...\";created=1234567890\n    const match = signatureInput.match(/sig1=\\((.*?)\\);(.+)/);\n    if (!match) return null;\n\n    const [, headersList, params] = match;\n    \n    // Parse signed headers\n    const signedHeaders = headersList\n      ? headersList\n          .split(' ')\n          .map(h => h.replace(/\"/g, '').trim())\n          .filter(h => h.length > 0)\n      : [];\n\n    // Parse parameters\n    const keyidMatch = params ? params.match(/keyid=\"([^\"]+)\"/) : null;\n    const createdMatch = params ? params.match(/created=(\\d+)/) : null;\n    const expiresMatch = params ? params.match(/expires=(\\d+)/) : null;\n\n    if (!keyidMatch || !keyidMatch[1]) return null;\n\n    return {\n      keyid: keyidMatch[1],\n      created: createdMatch && createdMatch[1] ? parseInt(createdMatch[1]) : undefined,\n      expires: expiresMatch && expiresMatch[1] ? parseInt(expiresMatch[1]) : undefined,\n      signedHeaders,\n    };\n  } catch (error) {\n    console.error('[Signature] Failed to parse Signature-Input:', error);\n    return null;\n  }\n}\n\n/**\n * Build the signature base string according to RFC 9421\n * This is what gets signed\n */\nfunction buildSignatureBase(\n  method: string,\n  path: string,\n  headers: Record<string, string>,\n  signedHeaders: string[]\n): string {\n  const components: string[] = [];\n  \n  for (const headerName of signedHeaders) {\n    let value: string;\n    \n    switch (headerName) {\n      case '@method':\n        value = method.toUpperCase();\n        break;\n      case '@path':\n        value = path;\n        break;\n      case '@authority':\n        // Get from Host header or URL\n        value = headers['host'] || headers['Host'] || '';\n        break;\n      default:\n        // Regular headers (case-insensitive lookup)\n        const key = Object.keys(headers).find(\n          k => k.toLowerCase() === headerName.toLowerCase()\n        );\n        value = key ? headers[key] || '' : '';\n        break;\n    }\n    \n    // Format according to RFC 9421\n    components.push(`\"${headerName}\": ${value}`);\n  }\n  \n  return components.join('\\n');\n}\n\n/**\n * Verify Ed25519 signature using Web Crypto API\n */\nasync function verifyEd25519Signature(\n  publicKeyBase64: string,\n  signatureBase64: string,\n  message: string\n): Promise<boolean> {\n  try {\n    // Decode base64 to Uint8Array\n    const publicKeyBytes = Uint8Array.from(atob(publicKeyBase64), c => c.charCodeAt(0));\n    const signatureBytes = Uint8Array.from(atob(signatureBase64), c => c.charCodeAt(0));\n    const messageBytes = new TextEncoder().encode(message);\n    \n    // Check key and signature lengths\n    if (publicKeyBytes.length !== 32) {\n      console.error('[Signature] Invalid public key length:', publicKeyBytes.length);\n      return false;\n    }\n    if (signatureBytes.length !== 64) {\n      console.error('[Signature] Invalid signature length:', signatureBytes.length);\n      return false;\n    }\n    \n    // Import the public key\n    const publicKey = await crypto.subtle.importKey(\n      'raw',\n      publicKeyBytes,\n      {\n        name: 'Ed25519',\n        namedCurve: 'Ed25519',\n      },\n      false,\n      ['verify']\n    );\n    \n    // Verify the signature\n    const isValid = await crypto.subtle.verify(\n      'Ed25519',\n      publicKey,\n      signatureBytes,\n      messageBytes\n    );\n    \n    return isValid;\n  } catch (error) {\n    console.error('[Signature] Ed25519 verification failed:', error);\n    \n    // Fallback: Try with @noble/ed25519 if available (for environments without Ed25519 support)\n    if (typeof window === 'undefined') {\n      try {\n        // In Node.js/Edge Runtime, we might need to use a polyfill\n        // For now, we'll return false if Web Crypto doesn't support Ed25519\n        console.warn('[Signature] Ed25519 not supported in this environment');\n        return false;\n      } catch {\n        return false;\n      }\n    }\n    \n    return false;\n  }\n}\n\n/**\n * Signature verification result\n */\nexport interface SignatureVerificationResult {\n  isValid: boolean;\n  agent?: string;\n  keyid?: string;\n  confidence: number;\n  reason?: string;\n  verificationMethod: 'signature' | 'none';\n}\n\n/**\n * Verify HTTP Message Signature for AI agents\n */\nexport async function verifyAgentSignature(\n  method: string,\n  path: string,\n  headers: Record<string, string>\n): Promise<SignatureVerificationResult> {\n  // Check for signature headers\n  const signature = headers['signature'] || headers['Signature'];\n  const signatureInput = headers['signature-input'] || headers['Signature-Input'];\n  const signatureAgent = headers['signature-agent'] || headers['Signature-Agent'];\n  \n  // No signature present\n  if (!signature || !signatureInput) {\n    return {\n      isValid: false,\n      confidence: 0,\n      reason: 'No signature headers present',\n      verificationMethod: 'none',\n    };\n  }\n  \n  // Parse Signature-Input header\n  const parsed = parseSignatureInput(signatureInput);\n  if (!parsed) {\n    return {\n      isValid: false,\n      confidence: 0,\n      reason: 'Invalid Signature-Input header',\n      verificationMethod: 'none',\n    };\n  }\n  \n  // Check timestamp if present\n  if (parsed.created) {\n    const now = Math.floor(Date.now() / 1000);\n    const age = now - parsed.created;\n    \n    // Reject signatures older than 5 minutes\n    if (age > 300) {\n      return {\n        isValid: false,\n        confidence: 0,\n        reason: 'Signature expired (older than 5 minutes)',\n        verificationMethod: 'none',\n      };\n    }\n    \n    // Reject signatures from the future (clock skew tolerance: 30 seconds)\n    if (age < -30) {\n      return {\n        isValid: false,\n        confidence: 0,\n        reason: 'Signature timestamp is in the future',\n        verificationMethod: 'none',\n      };\n    }\n  }\n  \n  // Determine which agent based on signature-agent header\n  let agent: string | undefined;\n  let knownKeys: typeof KNOWN_KEYS.chatgpt | undefined;\n  \n  if (signatureAgent === '\"https://chatgpt.com\"' || signatureAgent?.includes('chatgpt.com')) {\n    agent = 'ChatGPT';\n    knownKeys = KNOWN_KEYS.chatgpt;\n  }\n  // Add other agents here as needed\n  \n  if (!agent || !knownKeys) {\n    return {\n      isValid: false,\n      confidence: 0,\n      reason: 'Unknown signature agent',\n      verificationMethod: 'none',\n    };\n  }\n  \n  // Find the key by ID\n  const key = knownKeys.find(k => k.kid === parsed.keyid);\n  if (!key) {\n    return {\n      isValid: false,\n      confidence: 0,\n      reason: `Unknown key ID: ${parsed.keyid}`,\n      verificationMethod: 'none',\n    };\n  }\n  \n  // Check key validity period\n  const now = Math.floor(Date.now() / 1000);\n  if (now < key.validFrom || now > key.validUntil) {\n    return {\n      isValid: false,\n      confidence: 0,\n 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reason: 'Signature verification failed',\n      verificationMethod: 'none',\n    };\n  }\n}\n\n/**\n * Quick check if signature headers are present (for performance)\n */\nexport function hasSignatureHeaders(headers: Record<string, string>): boolean {\n  return !!(\n    (headers['signature'] || headers['Signature']) &&\n    (headers['signature-input'] || headers['Signature-Input'])\n  );\n}\n\n/**\n * Check if this is a ChatGPT signature based on headers\n */\nexport function isChatGPTSignature(headers: Record<string, string>): boolean {\n  const signatureAgent = headers['signature-agent'] || headers['Signature-Agent'];\n  return signatureAgent === '\"https://chatgpt.com\"' || (signatureAgent?.includes('chatgpt.com') || false);\n}"]}