Medowar
/
tool.medowar.de


			
				
					
						
						
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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>YubiKey NFC-ID Calculator</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            max-width: 600px;
            margin: 50px auto;
            padding: 20px;
        }
        .container {
            border: 1px solid #ccc;
            padding: 20px;
            border-radius: 5px;
        }
        label {
            display: block;
            margin-bottom: 10px;
            font-weight: bold;
        }
        input {
            width: 100%;
            padding: 8px;
            margin-bottom: 15px;
            box-sizing: border-box;
            font-size: 14px;
        }
        button {
            padding: 10px 20px;
            background-color: #007bff;
            color: white;
            border: none;
            border-radius: 4px;
            cursor: pointer;
            font-size: 14px;
        }
        button:hover {
            background-color: #0056b3;
        }
        .output {
            margin-top: 20px;
            padding: 15px;
            background-color: #f5f5f5;
            border-radius: 4px;
            font-family: monospace;
        }
        .output-label {
            font-weight: bold;
            margin-bottom: 5px;
        }
        .output-value {
            font-size: 16px;
            word-break: break-all;
        }
        .error {
            color: red;
            margin-top: 10px;
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>YubiKey NFC-ID Calculator</h1>
        <p>Enter a YubiKey serial number (decimal) to calculate its NFC-ID (v5.3.0+ format).</p>
        
        <label for="serialNumber">Serial Number (Decimal):</label>
        <input type="number" id="serialNumber" placeholder="e.g., 23852733" min="0" step="1">
        
        <button onclick="calculateNFCID()">Calculate NFC-ID</button>
        
        <div id="output"></div>
        <div id="error" class="error"></div>
    </div>

    <script>
        function calculateNFCID() {
            const serialInput = document.getElementById('serialNumber').value;
            const errorDiv = document.getElementById('error');
            const outputDiv = document.getElementById('output');
            
            // Clear previous output
            errorDiv.textContent = '';
            outputDiv.innerHTML = '';
            
            // Validate input
            if (!serialInput || serialInput.trim() === '') {
                errorDiv.textContent = 'Please enter a serial number.';
                return;
            }
            
            const serialNumber = parseInt(serialInput, 10);
            
            if (isNaN(serialNumber) || serialNumber < 0) {
                errorDiv.textContent = 'Please enter a valid positive number.';
                return;
            }
            
            // Convert to hex and pad to 8 characters (4 bytes)
            let hexString = serialNumber.toString(16).toLowerCase();
            hexString = hexString.padStart(8, '0');
            
            // Extract the 4 bytes
            // serial_0 is most significant (leftmost), serial_3 is least significant (rightmost)
            const serial_0 = hexString.substring(0, 2);
            const serial_1 = hexString.substring(2, 4);
            const serial_2 = hexString.substring(4, 6);
            const serial_3 = hexString.substring(6, 8);
            
            // Calculate NFC-ID according to formula:
            // 0x88 0x27 serial_3 serial_2 serial_1 serial_0 serial_2 serial_3
            // Based on user example, they want: 27 serial_3 serial_2 serial_1 serial_0 serial_2 serial_3
            const nfcId = '27' + serial_3 + serial_2 + serial_1 + serial_0 + serial_2 + serial_3;
            
            // Display results
            outputDiv.innerHTML = `
                <div class="output">
                    <div class="output-label">Serial Number (Hex):</div>
                    <div class="output-value">${hexString}</div>
                </div>
                <div class="output">
                    <div class="output-label">NFC-ID:</div>
                    <div class="output-value">${nfcId}</div>
                </div>
            `;
        }
        
        // Allow Enter key to trigger calculation
        document.getElementById('serialNumber').addEventListener('keypress', function(e) {
            if (e.key === 'Enter') {
                calculateNFCID();
            }
        });
    </script>
</body>
</html>