3bbec5a4ac
Upgraded `encodeAssetId` and `decodeAssetId` to use `aes-256-gcm` (Authenticated Encryption) instead of `aes-256-cbc`. AES-CBC lacks authentication, leaving it potentially susceptible to padding oracle attacks or ciphertext manipulation. The new token adds a `v2:` prefix which strictly enforces AES-GCM while supporting legacy fallback for cached urls. Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
81 lines
2.9 KiB
TypeScript
81 lines
2.9 KiB
TypeScript
/**
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* Token encoding/decoding for asset IDs.
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* Obfuscates Immich UUIDs in public-facing URLs using AES encryption.
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*
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* Uses deterministic encryption (IV derived from asset ID) so the same
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* asset always produces the same token — essential for browser caching.
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*/
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import crypto from 'crypto';
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import { getConfig } from './config';
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let _key: Buffer | null = null;
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function getKey(): Buffer {
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if (!_key) {
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const authSecret = getConfig().authSecret;
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_key = crypto.createHash('sha256').update(authSecret).digest();
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}
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return _key;
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}
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/**
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* Encode an asset ID into an opaque URL-safe token.
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* Note: The AES-GCM deterministic IV causes the identical input asset ID
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* to encrypt to the exact same cipher token. This provides URL obfuscation
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* and caching consistency, but it does NOT provide k-anonymous cryptographic
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* security guarantees against recognizing identical items if intercepted.
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*/
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export function encodeAssetId(assetId: string): string {
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const key = getKey();
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// Deterministic IV from asset ID (same input → same token).
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// SHA-256 slice → first 16 bytes. MD5 was deprecated for cryptographic use.
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const iv = crypto.createHash('sha256').update(assetId).digest().subarray(0, 16);
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const cipher = crypto.createCipheriv('aes-256-gcm', key, iv);
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const encrypted = Buffer.concat([cipher.update(assetId, 'utf8'), cipher.final()]);
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const authTag = cipher.getAuthTag();
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// Compact: base64url(iv + authTag + ciphertext) with v2 prefix
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const payload = Buffer.concat([iv, authTag, encrypted]).toString('base64url');
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return `v2:${payload}`;
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}
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/**
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* Decode a token back into an asset ID.
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* Returns null if the token is invalid.
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*/
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export function decodeAssetId(token: string): string | null {
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try {
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const key = getKey();
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let decrypted: string;
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if (token.startsWith('v2:')) {
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const data = Buffer.from(token.slice(3), 'base64url');
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if (data.length < 33) return null; // iv(16) + authTag(16) + at least 1 byte
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const iv = data.subarray(0, 16);
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const authTag = data.subarray(16, 32);
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const encrypted = data.subarray(32);
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const decipher = crypto.createDecipheriv('aes-256-gcm', key, iv);
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decipher.setAuthTag(authTag);
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decrypted = Buffer.concat([decipher.update(encrypted), decipher.final()]).toString('utf8');
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} else {
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// Legacy aes-256-cbc fallback
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const data = Buffer.from(token, 'base64url');
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if (data.length < 17) return null; // iv(16) + at least 1 byte
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const iv = data.subarray(0, 16);
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const encrypted = data.subarray(16);
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const decipher = crypto.createDecipheriv('aes-256-cbc', key, iv);
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decrypted = Buffer.concat([decipher.update(encrypted), decipher.final()]).toString('utf8');
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}
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// Validate it looks like a UUID
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const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
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return uuidRegex.test(decrypted) ? decrypted : null;
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} catch {
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return null;
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}
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}
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