authorization-jwt-verifier/index.html at main · STARTcloud/authorization-jwt-verifier · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>JWT RS256 Verification</title>
    <style>
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            max-width: 1200px;
            margin: 0 auto;
            padding: 20px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
        }
        .container {
            background: white;
            border-radius: 12px;
            padding: 30px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.2);
        }
        h1 {
            color: #333;
            text-align: center;
            margin-bottom: 30px;
        }
        .input-group {
            margin-bottom: 20px;
        }
        label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: #555;
        }
        input, textarea {
            width: 100%;
            padding: 12px;
            border: 2px solid #e1e5e9;
            border-radius: 8px;
            font-size: 14px;
            font-family: monospace;
            transition: border-color 0.3s;
        }
        input:focus, textarea:focus {
            outline: none;
            border-color: #667eea;
        }
        textarea {
            height: 120px;
            resize: vertical;
        }
        button {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: white;
            border: none;
            padding: 12px 24px;
            border-radius: 8px;
            cursor: pointer;
            font-size: 16px;
            font-weight: 600;
            transition: transform 0.2s;
        }
        button:hover {
            transform: translateY(-2px);
        }
        button:disabled {
            background: #ccc;
            cursor: not-allowed;
            transform: none;
        }
        .result {
            margin-top: 20px;
            padding: 20px;
            border-radius: 8px;
            font-family: monospace;
            white-space: pre-wrap;
            max-height: 400px;
            overflow-y: auto;
        }
        .success {
            background: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }
        .error {
            background: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        .info {
            background: #d1ecf1;
            border: 1px solid #bee5eb;
            color: #0c5460;
        }
        .loading {
            text-align: center;
            color: #666;
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>🔐 JWT RS256 Verification Tool</h1>

        <div class="input-group">
            <label for="jwksUrl">JWKS Endpoint URL:</label>
            <input type="url" id="jwksUrl" value="https://dev-auth.moonshine.dev/oauth2/jwks" placeholder="https://example.com/.well-known/jwks.json">
        </div>

        <div class="input-group">
            <label for="jwtToken">JWT Token:</label>
            <textarea id="jwtToken" placeholder="Paste your JWT token here..."></textarea>
        </div>

        <button onclick="verifyToken()" id="verifyBtn">🔍 Verify Token</button>

        <div id="result"></div>
    </div>

    <script>
        class BrowserJWTVerifier {
            constructor() {
                this.keyCache = new Map();
            }

            // Fetch JWKS from endpoint
            async fetchJWKS(url) {
                const response = await fetch(url);
                if (!response.ok) {
                    throw new Error(`Failed to fetch JWKS: ${response.status} ${response.statusText}`);
                }
                return await response.json();
            }

            // Base64URL decode
            base64UrlDecode(str) {
                // Replace URL-safe characters
                str = str.replace(/-/g, '+').replace(/_/g, '/');
                // Add padding
                while (str.length % 4) {
                    str += '=';
                }
                return Uint8Array.from(atob(str), c => c.charCodeAt(0));
            }

            // Base64URL encode
            base64UrlEncode(buffer) {
                return btoa(String.fromCharCode(...new Uint8Array(buffer)))
                    .replace(/\+/g, '-')
                    .replace(/\//g, '_')
                    .replace(/=/g, '');
            }

            // Convert JWK to CryptoKey using Web Crypto API
            async jwkToCryptoKey(jwk) {
                if (jwk.kty !== 'RSA') {
                    throw new Error('Only RSA keys are supported');
                }

                // Import the JWK as a CryptoKey
                return await crypto.subtle.importKey(
                    'jwk',
                    {
                        kty: jwk.kty,
                        n: jwk.n,
                        e: jwk.e,
                        alg: 'RS256',
                        use: 'sig'
                    },
                    {
                        name: 'RSASSA-PKCS1-v1_5',
                        hash: 'SHA-256'
                    },
                    false,
                    ['verify']
                );
            }

            // Get public key for given kid
            async getPublicKey(kid, jwksUrl) {
                const cacheKey = `${jwksUrl}:${kid}`;
                if (this.keyCache.has(cacheKey)) {
                    return this.keyCache.get(cacheKey);
                }

                const jwks = await this.fetchJWKS(jwksUrl);
                const jwk = jwks.keys.find(key => key.kid === kid);

                if (!jwk) {
                    throw new Error(`Key with kid "${kid}" not found in JWKS. Available keys: ${jwks.keys.map(k => k.kid).join(', ')}`);
                }

                const cryptoKey = await this.jwkToCryptoKey(jwk);
                this.keyCache.set(cacheKey, cryptoKey);
                return cryptoKey;
            }

            // Decode JWT parts
            decodeJWT(token) {
                const parts = token.split('.');
                if (parts.length !== 3) {
                    throw new Error('Invalid JWT format - must have 3 parts separated by dots');
                }

                const [headerB64, payloadB64, signatureB64] = parts;

                try {
                    const headerBytes = this.base64UrlDecode(headerB64);
                    const header = JSON.parse(new TextDecoder().decode(headerBytes));

                    const payloadBytes = this.base64UrlDecode(payloadB64);
                    const payload = JSON.parse(new TextDecoder().decode(payloadBytes));

                    const signature = this.base64UrlDecode(signatureB64);

                    return { header, payload, signature, headerB64, payloadB64 };
                } catch (error) {
                    throw new Error(`Failed to decode JWT: ${error.message}`);
                }
            }

            // Format timestamp for display
            formatTimestamp(timestamp) {
                return new Date(timestamp * 1000).toISOString();
            }

            // Verify JWT token
            async verifyToken(token, jwksUrl) {
                const result = {
                    valid: false,
                    header: null,
                    payload: null,
                    errors: [],
                    warnings: [],
                    info: []
                };

                try {
                    // Decode JWT
                    const { header, payload, signature, headerB64, payloadB64 } = this.decodeJWT(token);
                    result.header = header;
                    result.payload = payload;

                    result.info.push(`Token decoded successfully`);
                    result.info.push(`Algorithm: ${header.alg}`);
                    result.info.push(`Key ID: ${header.kid}`);
                    result.info.push(`Subject: ${payload.sub || 'N/A'}`);
                    result.info.push(`Issuer: ${payload.iss || 'N/A'}`);
                    result.info.push(`Audience: ${payload.aud || 'N/A'}`);

                    // Verify algorithm
                    if (header.alg !== 'RS256') {
                        throw new Error(`Unsupported algorithm: ${header.alg}. Only RS256 is supported.`);
                    }

                    // Check timing claims
                    const now = Math.floor(Date.now() / 1000);

                    if (payload.iat) {
                        result.info.push(`Issued at: ${this.formatTimestamp(payload.iat)}`);
                    }

                    if (payload.exp) {
                        result.info.push(`Expires at: ${this.formatTimestamp(payload.exp)}`);
                        if (now >= payload.exp) {
                            result.errors.push(`Token has expired (expired ${now - payload.exp} seconds ago)`);
                        }
                    } else {
                        result.warnings.push('Token has no expiration time (exp claim)');
                    }

                    if (payload.nbf) {
                        result.info.push(`Not valid before: ${this.formatTimestamp(payload.nbf)}`);
                        if (now < payload.nbf) {
                            result.errors.push(`Token not yet valid (${payload.nbf - now} seconds until valid)`);
                        }
                    }

                    // Get public key and verify signature
                    let publicKey;
                    try {
                        publicKey = await this.getPublicKey(header.kid, jwksUrl);
                        result.info.push('✅ Matching public key found in JWKS');
                    } catch (keyError) {
                        result.errors.push(`Key retrieval failed: ${keyError.message}`);
                        throw keyError;
                    }

                    // Verify signature using Web Crypto API
                    const signatureData = new TextEncoder().encode(`${headerB64}.${payloadB64}`);
                    const isValidSignature = await crypto.subtle.verify(
                        'RSASSA-PKCS1-v1_5',
                        publicKey,
                        signature,
                        signatureData
                    );

                    if (!isValidSignature) {
                        result.errors.push('❌ Invalid signature - token may be tampered with');
                    } else {
                        result.info.push('✅ Signature is valid');
                    }

                    // Overall validity
                    result.valid = isValidSignature && result.errors.length === 0;

                    if (result.valid) {
                        result.info.push('🎉 Token is completely valid!');
                    } else if (isValidSignature && result.errors.length > 0) {
                        result.info.push('⚠️ Token signature is valid but has other issues (likely expired)');
                    }

                } catch (error) {
                    result.errors.push(`Verification failed: ${error.message}`);
                }

                return result;
            }
        }

        // Global verifier instance
        const verifier = new BrowserJWTVerifier();

        // Verify token function
        async function verifyToken() {
            const jwksUrl = document.getElementById('jwksUrl').value.trim();
            const token = document.getElementById('jwtToken').value.trim();
            const resultDiv = document.getElementById('result');
            const verifyBtn = document.getElementById('verifyBtn');

            if (!jwksUrl || !token) {
                resultDiv.innerHTML = '<div class="result error">Please provide both JWKS URL and JWT token</div>';
                return;
            }

            // Show loading state
            verifyBtn.disabled = true;
            verifyBtn.textContent = '🔄 Verifying...';
            resultDiv.innerHTML = '<div class="result loading">Verifying token...</div>';

            try {
                const result = await verifier.verifyToken(token, jwksUrl);

                let output = '';
                let resultClass = '';

                if (result.valid) {
                    resultClass = 'success';
                    output += '🎉 TOKEN IS VALID!\n\n';
                } else {
                    resultClass = 'error';
                    output += '❌ TOKEN VERIFICATION FAILED\n\n';
                }

                // Show errors
                if (result.errors.length > 0) {
                    output += '🚨 ERRORS:\n';
                    result.errors.forEach(error => output += `  • ${error}\n`);
                    output += '\n';
                }

                // Show warnings
                if (result.warnings.length > 0) {
                    output += '⚠️ WARNINGS:\n';
                    result.warnings.forEach(warning => output += `  • ${warning}\n`);
                    output += '\n';
                }

                // Show info
                if (result.info.length > 0) {
                    output += 'ℹ️ INFORMATION:\n';
                    result.info.forEach(info => output += `  • ${info}\n`);
                    output += '\n';
                }

                // Show decoded payload
                if (result.payload) {
                    output += '📋 DECODED PAYLOAD:\n';
                    output += JSON.stringify(result.payload, null, 2);
                }

                resultDiv.innerHTML = `<div class="result ${resultClass}">${output}</div>`;

            } catch (error) {
                resultDiv.innerHTML = `<div class="result error">❌ Unexpected error: ${error.message}</div>`;
            } finally {
                verifyBtn.disabled = false;
                verifyBtn.textContent = '🔍 Verify Token';
            }
        }

        // Allow Enter key to trigger verification
        document.addEventListener('keydown', function(event) {
            if (event.key === 'Enter' && (event.ctrlKey || event.metaKey)) {
                verifyToken();
            }
        });

        // Auto-verify on page load with demo token
        window.addEventListener('load', function() {
            // Small delay to ensure everything is loaded
            setTimeout(() => {
                const token = document.getElementById('jwtToken').value;
                if (token.trim()) {
                    verifyToken();
                }
            }, 500);
        });
    </script>
</body>
</html>