Lucas Berger
982438dc10
Mechanical reformat — no logic changes. 398 files changed, 19125 insertions(+), 16457 deletions(-). Prettier 3.8.4 with .prettierrc (singleQuote:true, semi:true, tabWidth:2, trailingComma:all, printWidth:100). Isolated per D-13-08 for reviewability.
70 lines
2.6 KiB
TypeScript
70 lines
2.6 KiB
TypeScript
/**
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* AES-256-GCM encryption helpers for Fastmail app-password storage.
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*
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* Security requirements (T-03-01, T-03-03, ASVS V6):
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* - Key from APP_PASSWORD_ENCRYPTION_KEY env (64-char hex = 32 bytes)
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* - 96-bit (12-byte) random IV per encryption — never reuse IV
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* - GCM auth tag verifies integrity on decrypt; tampered ciphertext throws
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* - Stored payload: JSON { iv, authTag, ciphertext } (all hex)
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* - Never log plaintext or the encryption key
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*
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* Source: Node.js docs node:crypto — AES-GCM
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*/
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import { randomBytes, createCipheriv, createDecipheriv } from 'node:crypto';
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// Validated at module load: key must be present and 32 bytes (64 hex chars).
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// We deliberately do NOT throw here on missing key — that would crash the module
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// during tests that set the env before the first import. The KEY is only read
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// when encryptPassword / decryptPassword are actually called.
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function getKey(): Buffer {
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const hex = process.env.APP_PASSWORD_ENCRYPTION_KEY;
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if (!hex || hex.length !== 64) {
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throw new Error(
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'APP_PASSWORD_ENCRYPTION_KEY must be a 64-character hex string (32 bytes). ' +
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"Generate with: node -e \"console.log(require('crypto').randomBytes(32).toString('hex'))\"",
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);
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}
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return Buffer.from(hex, 'hex');
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}
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interface EncryptedPayload {
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iv: string;
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authTag: string;
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ciphertext: string;
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}
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/**
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* Encrypts a plaintext string using AES-256-GCM.
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* Returns a JSON string with { iv, authTag, ciphertext } — all hex-encoded.
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* Each call generates a fresh random 96-bit IV.
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*/
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export function encryptPassword(plaintext: string): string {
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const key = getKey();
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const iv = randomBytes(12); // 96-bit IV for GCM
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const cipher = createCipheriv('aes-256-gcm', key, iv);
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const encrypted = Buffer.concat([cipher.update(plaintext, 'utf8'), cipher.final()]);
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const authTag = cipher.getAuthTag();
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const payload: EncryptedPayload = {
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iv: iv.toString('hex'),
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authTag: authTag.toString('hex'),
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ciphertext: encrypted.toString('hex'),
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};
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return JSON.stringify(payload);
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}
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/**
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* Decrypts an AES-256-GCM encrypted payload produced by encryptPassword.
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* Throws if the auth tag does not match (integrity violation).
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*/
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export function decryptPassword(stored: string): string {
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const key = getKey();
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const { iv, authTag, ciphertext } = JSON.parse(stored) as EncryptedPayload;
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const decipher = createDecipheriv('aes-256-gcm', key, Buffer.from(iv, 'hex'));
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decipher.setAuthTag(Buffer.from(authTag, 'hex'));
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return Buffer.concat([
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decipher.update(Buffer.from(ciphertext, 'hex')),
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decipher.final(),
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]).toString('utf8');
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}
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