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video.py must sign video urls for serve-files.js to serve them
author drewp@bigasterisk.com
date Fri, 06 Dec 2024 17:13:51 -0800
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48:046673b1cc24 49:1bd17c2e5517
1 import { createDecipheriv } from 'crypto';
2 import * as fs from 'fs';
3
4 const SIGNATURE_KEY = fs.readFileSync('/secret/signature_key');
5
6 function removePKCS7Padding(data) {
7 const paddingLength = data.charCodeAt(data.length - 1);
8 return data.slice(0, -paddingLength);
9 }
10
11 function decryptData(encryptedData, key) {
12 const ivLength = 12; // 12 bytes for GCM
13 const tagLength = 16; // 16 bytes for GCM
14 const decodedData = Buffer.from(encryptedData, 'base64');
15
16 if (decodedData.length < ivLength + tagLength) {
17 throw new Error('Invalid encrypted data length');
18 }
19
20 const iv = decodedData.slice(0, ivLength);
21 const tag = decodedData.slice(-tagLength);
22 const ciphertext = decodedData.slice(ivLength, -tagLength);
23
24 const decipher = createDecipheriv('aes-256-gcm', key, iv);
25 decipher.setAuthTag(tag);
26 let decryptedData = decipher.update(ciphertext, 'base64', 'utf8');
27 decryptedData += decipher.final('utf8');
28 return decryptedData;
29 }
30
31 export function decodeSig(sig) {
32 const clear = decryptData(sig, SIGNATURE_KEY);
33 const json = removePKCS7Padding(clear.toString('utf-8'));
34 return JSON.parse(json);
35 }