feat: add server crypto (#863)

## Description

Currently we are required to ensure PII data is not passed around in
search parameters and in the open for GDPR reasons.

Allowing us to encrypt and decrypt values with expiry dates will allow
us to ensure this doesn't happen.

## Changes Made

- Added TPRC router for encryption method

## Testing Performed

- Tested encrypting and decrypting data with and without `expiredAt`
- Tested via directly accessing API and also via trpc in react
components
- Tested parsing en email search param in a page and decrypting it
successfully

## Checklist

- [X] I have tested these changes locally and they work as expected.
- [X] I have followed the project's coding style guidelines.

.env.example

@@ -4,8 +4,10 @@ NEXTAUTH_SECRET="secret"
 
 # [[CRYPTO]]
 # Application Key for symmetric encryption and decryption
-# This should be a random string of at least 32 characters
-NEXT_PRIVATE_ENCRYPTION_KEY="CAFEBABE"
+# REQUIRED: This should be a random string of at least 32 characters
+NEXT_PRIVATE_ENCRYPTION_KEY=""
+# REQUIRED: This should be a random string of at least 32 characters
+NEXT_PRIVATE_ENCRYPTION_SECONDARY_KEY=""
 
 # [[AUTH OPTIONAL]]
 NEXT_PRIVATE_GOOGLE_CLIENT_ID=""

packages/lib/constants/crypto.ts

@@ -1 +1,23 @@
 export const DOCUMENSO_ENCRYPTION_KEY = process.env.NEXT_PRIVATE_ENCRYPTION_KEY;
+
+export const DOCUMENSO_ENCRYPTION_SECONDARY_KEY = process.env.NEXT_PRIVATE_ENCRYPTION_SECONDARY_KEY;
+
+if (!DOCUMENSO_ENCRYPTION_KEY || !DOCUMENSO_ENCRYPTION_SECONDARY_KEY) {
+  throw new Error('Missing DOCUMENSO_ENCRYPTION_KEY or DOCUMENSO_ENCRYPTION_SECONDARY_KEY keys');
+}
+
+if (DOCUMENSO_ENCRYPTION_KEY === DOCUMENSO_ENCRYPTION_SECONDARY_KEY) {
+  throw new Error(
+    'DOCUMENSO_ENCRYPTION_KEY and DOCUMENSO_ENCRYPTION_SECONDARY_KEY cannot be equal',
+  );
+}
+
+if (DOCUMENSO_ENCRYPTION_KEY === 'CAFEBABE') {
+  console.warn('*********************************************************************');
+  console.warn('*');
+  console.warn('*');
+  console.warn('Please change the encryption key from the default value of "CAFEBABE"');
+  console.warn('*');
+  console.warn('*');
+  console.warn('*********************************************************************');
+}

packages/lib/server-only/crypto/decrypt.ts

@@ -0,0 +1,33 @@
+import { DOCUMENSO_ENCRYPTION_SECONDARY_KEY } from '@documenso/lib/constants/crypto';
+import { ZEncryptedDataSchema } from '@documenso/lib/server-only/crypto/encrypt';
+import { symmetricDecrypt } from '@documenso/lib/universal/crypto';
+
+/**
+ * Decrypt the passed in data. This uses the secondary encrypt key for miscellaneous data.
+ *
+ * @param encryptedData The data encrypted with the `encryptSecondaryData` function.
+ * @returns The decrypted value, or `null` if the data is invalid or expired.
+ */
+export const decryptSecondaryData = (encryptedData: string): string | null => {
+  if (!DOCUMENSO_ENCRYPTION_SECONDARY_KEY) {
+    throw new Error('Missing encryption key');
+  }
+
+  const decryptedBufferValue = symmetricDecrypt({
+    key: DOCUMENSO_ENCRYPTION_SECONDARY_KEY,
+    data: encryptedData,
+  });
+
+  const decryptedValue = Buffer.from(decryptedBufferValue).toString('utf-8');
+  const result = ZEncryptedDataSchema.safeParse(JSON.parse(decryptedValue));
+
+  if (!result.success) {
+    return null;
+  }
+
+  if (result.data.expiresAt !== undefined && result.data.expiresAt < Date.now()) {
+    return null;
+  }
+
+  return result.data.data;
+};

packages/lib/server-only/crypto/encrypt.ts

@@ -0,0 +1,42 @@
+import { z } from 'zod';
+
+import { DOCUMENSO_ENCRYPTION_SECONDARY_KEY } from '@documenso/lib/constants/crypto';
+import { symmetricEncrypt } from '@documenso/lib/universal/crypto';
+import type { TEncryptSecondaryDataMutationSchema } from '@documenso/trpc/server/crypto/schema';
+
+export const ZEncryptedDataSchema = z.object({
+  data: z.string(),
+  expiresAt: z.number().optional(),
+});
+
+export type EncryptDataOptions = {
+  data: string;
+
+  /**
+   * When the data should no longer be allowed to be decrypted.
+   *
+   * Leave this empty to never expire the data.
+   */
+  expiresAt?: number;
+};
+
+/**
+ * Encrypt the passed in data. This uses the secondary encrypt key for miscellaneous data.
+ *
+ * @returns The encrypted data.
+ */
+export const encryptSecondaryData = ({ data, expiresAt }: TEncryptSecondaryDataMutationSchema) => {
+  if (!DOCUMENSO_ENCRYPTION_SECONDARY_KEY) {
+    throw new Error('Missing encryption key');
+  }
+
+  const dataToEncrypt: z.infer<typeof ZEncryptedDataSchema> = {
+    data,
+    expiresAt,
+  };
+
+  return symmetricEncrypt({
+    key: DOCUMENSO_ENCRYPTION_SECONDARY_KEY,
+    data: JSON.stringify(dataToEncrypt),
+  });
+};

packages/trpc/server/crypto/router.ts

@@ -0,0 +1,17 @@
+import { encryptSecondaryData } from '@documenso/lib/server-only/crypto/encrypt';
+
+import { procedure, router } from '../trpc';
+import { ZEncryptSecondaryDataMutationSchema } from './schema';
+
+export const cryptoRouter = router({
+  encryptSecondaryData: procedure
+    .input(ZEncryptSecondaryDataMutationSchema)
+    .mutation(({ input }) => {
+      try {
+        return encryptSecondaryData(input);
+      } catch {
+        // Never leak errors for crypto.
+        throw new Error('Failed to encrypt data');
+      }
+    }),
+});

packages/trpc/server/crypto/schema.ts

@@ -0,0 +1,15 @@
+import { z } from 'zod';
+
+export const ZEncryptSecondaryDataMutationSchema = z.object({
+  data: z.string(),
+  expiresAt: z.number().optional(),
+});
+
+export const ZDecryptDataMutationSchema = z.object({
+  data: z.string(),
+});
+
+export type TEncryptSecondaryDataMutationSchema = z.infer<
+  typeof ZEncryptSecondaryDataMutationSchema
+>;
+export type TDecryptDataMutationSchema = z.infer<typeof ZDecryptDataMutationSchema>;

packages/trpc/server/router.ts

@@ -1,5 +1,6 @@
 import { adminRouter } from './admin-router/router';
 import { authRouter } from './auth-router/router';
+import { cryptoRouter } from './crypto/router';
 import { documentRouter } from './document-router/router';
 import { fieldRouter } from './field-router/router';
 import { profileRouter } from './profile-router/router';
@@ -12,6 +13,7 @@ import { twoFactorAuthenticationRouter } from './two-factor-authentication-route
 
 export const appRouter = router({
   auth: authRouter,
+  crypto: cryptoRouter,
   profile: profileRouter,
   document: documentRouter,
   field: fieldRouter,

packages/tsconfig/process-env.d.ts

@@ -8,6 +8,7 @@ declare namespace NodeJS {
 
     NEXT_PRIVATE_DATABASE_URL: string;
     NEXT_PRIVATE_ENCRYPTION_KEY: string;
+    NEXT_PRIVATE_ENCRYPTION_SECONDARY_KEY: string;
 
     NEXT_PUBLIC_STRIPE_COMMUNITY_PLAN_MONTHLY_PRICE_ID: string;
 

turbo.json

@@ -34,6 +34,7 @@
   "globalEnv": [
     "APP_VERSION",
     "NEXT_PRIVATE_ENCRYPTION_KEY",
+    "NEXT_PRIVATE_ENCRYPTION_SECONDARY_KEY",
     "NEXTAUTH_URL",
     "NEXTAUTH_SECRET",
     "NEXT_PUBLIC_PROJECT",