feat(server): add global encryption module (AES-256-GCM) (#2400)

Provides an injectable EncryptionService that encrypts/decrypts strings with AES-256-GCM using a key derived from APP_SECRET with domain separation.
2026-08-27 08:47:06 +08:00 · 2026-08-16 12:35:37 +01:00
parent d136864ef1
commit 911c1057d6
5 changed files with 316 additions and 0 deletions
@@ -0,0 +1,108 @@
+// https://github.com/nhedger/nestjs-encryption - MIT
+import { Injectable } from '@nestjs/common';
+import {
+  createCipheriv,
+  createDecipheriv,
+  createHash,
+  randomBytes,
+} from 'node:crypto';
+import { UnableToDecrypt, UnableToInitialize } from './encryption.errors';
+import { EnvironmentService } from '../environment/environment.service';
+
+const ALGORITHM = 'aes-256-gcm';
+const KEY_DOMAIN = 'docmost:encryption:v1';
+const IV_LENGTH = 12;
+const AUTH_TAG_LENGTH = 16;
+
+type AEADPayload<TFormat = string | Buffer> = {
+  iv: TFormat;
+  authTag: TFormat;
+  cipherText: TFormat;
+};
+
+@Injectable()
+export class EncryptionService {
+  private readonly key: Buffer;
+
+  constructor(environmentService: EnvironmentService) {
+    const appSecret = environmentService.getAppSecret();
+    if (!appSecret) {
+      throw new UnableToInitialize('APP_SECRET is not set.');
+    }
+    this.key = createHash('sha256')
+      .update(KEY_DOMAIN)
+      .update(appSecret)
+      .digest();
+  }
+
+  public encrypt(plaintext: string): string {
+    const iv = randomBytes(IV_LENGTH);
+    const cipher = createCipheriv(ALGORITHM, this.key, iv);
+    const cipherText = Buffer.concat([
+      cipher.update(plaintext, 'utf8'),
+      cipher.final(),
+    ]);
+    const authTag = cipher.getAuthTag();
+
+    const aead: AEADPayload<string> = {
+      iv: iv.toString('base64'),
+      authTag: authTag.toString('base64'),
+      cipherText: cipherText.toString('base64'),
+    };
+
+    return Buffer.from(JSON.stringify(aead)).toString('base64');
+  }
+
+  public decrypt(encrypted: string): string {
+    try {
+      const { iv, authTag, cipherText } = this.decodeAEADPayload(encrypted);
+      const decipher = createDecipheriv(ALGORITHM, this.key, iv);
+      decipher.setAuthTag(authTag);
+      const decrypted = Buffer.concat([
+        decipher.update(cipherText),
+        decipher.final(),
+      ]);
+      return decrypted.toString('utf8');
+    } catch (e: unknown) {
+      throw new UnableToDecrypt((e as Error).message);
+    }
+  }
+
+  private decodeAEADPayload(encodedPayload: string): AEADPayload<Buffer> {
+    const payload = Buffer.from(encodedPayload, 'base64');
+
+    let deserializedPkg: Record<string, unknown>;
+    try {
+      deserializedPkg = JSON.parse(payload.toString());
+    } catch {
+      throw new Error('The decoded AEAD payload is not a valid JSON string.');
+    }
+
+    for (const field of ['iv', 'authTag', 'cipherText']) {
+      if (!Object.prototype.hasOwnProperty.call(deserializedPkg, field)) {
+        throw new Error(`The AEAD payload is missing the ${field} field.`);
+      }
+    }
+
+    const iv = Buffer.from(deserializedPkg.iv as string, 'base64');
+    if (iv.length !== IV_LENGTH) {
+      throw new Error(
+        `The decoded IV is not the correct length. Expected ${IV_LENGTH} bytes, got ${iv.length} bytes.`,
+      );
+    }
+
+    const authTag = Buffer.from(deserializedPkg.authTag as string, 'base64');
+    if (authTag.length !== AUTH_TAG_LENGTH) {
+      throw new Error(
+        `The decoded auth tag is not the correct length. Expected ${AUTH_TAG_LENGTH} bytes, got ${authTag.length} bytes.`,
+      );
+    }
+
+    const cipherText = Buffer.from(
+      deserializedPkg.cipherText as string,
+      'base64',
+    );
+
+    return { iv, authTag, cipherText };
+  }
+}