Encrypt raw transaction payload storage

src/common/common.module.ts

@@ -1,11 +1,12 @@
 import { Global, Module } from "@nestjs/common";
 import { EncryptionService } from "./encryption.service";
 import { OpaqueIdService } from "./opaque-id.service";
+import { RawPayloadEncryptionService } from "./raw-payload-encryption.service";
 import { ViewRefService } from "./view-ref.service";
 
 @Global()
 @Module({
-  providers: [EncryptionService, OpaqueIdService, ViewRefService],
+  providers: [EncryptionService, OpaqueIdService, RawPayloadEncryptionService, ViewRefService],
-  exports: [EncryptionService, OpaqueIdService, ViewRefService],
+  exports: [EncryptionService, OpaqueIdService, RawPayloadEncryptionService, ViewRefService],
 })
 export class CommonModule {}

src/common/raw-payload-encryption.service.ts

@@ -0,0 +1,37 @@
+import { Injectable } from "@nestjs/common";
+import { Prisma } from "@prisma/client";
+import { EncryptionService } from "./encryption.service";
+
+type EncryptedRawPayload = {
+  encrypted: true;
+  version: 1;
+  ciphertext: string;
+};
+
+@Injectable()
+export class RawPayloadEncryptionService {
+  constructor(private readonly encryption: EncryptionService) {}
+
+  encrypt(payload: unknown): Prisma.InputJsonValue {
+    return {
+      encrypted: true,
+      version: 1,
+      ciphertext: this.encryption.encrypt(JSON.stringify(payload ?? null)),
+    } satisfies EncryptedRawPayload as unknown as Prisma.InputJsonValue;
+  }
+
+  decrypt<T = unknown>(payload: unknown): T {
+    if (!this.isEncryptedPayload(payload)) return payload as T;
+    return JSON.parse(this.encryption.decrypt(payload.ciphertext)) as T;
+  }
+
+  private isEncryptedPayload(payload: unknown): payload is EncryptedRawPayload {
+    return Boolean(
+      payload &&
+      typeof payload === "object" &&
+      (payload as { encrypted?: unknown }).encrypted === true &&
+      (payload as { version?: unknown }).version === 1 &&
+      typeof (payload as { ciphertext?: unknown }).ciphertext === "string",
+    );
+  }
+}

src/plaid/plaid.service.ts

@@ -10,6 +10,7 @@ import * as crypto from "crypto";
 import { Prisma } from "@prisma/client";
 import { PrismaService } from "../prisma/prisma.service";
 import { EncryptionService } from "../common/encryption.service";
+import { RawPayloadEncryptionService } from "../common/raw-payload-encryption.service";
 import { PlanLimitsService } from "../stripe/plan-limits.service";
 
 @Injectable()
@@ -22,6 +23,7 @@ export class PlaidService {
     private readonly prisma: PrismaService,
     private readonly encryption: EncryptionService,
     private readonly planLimits: PlanLimitsService,
+    private readonly rawPayloads: RawPayloadEncryptionService,
   ) {
     const env = (process.env.PLAID_ENV ?? "sandbox") as keyof typeof PlaidEnvironments;
     const clientId = this.requireEnv("PLAID_CLIENT_ID");
@@ -204,7 +206,7 @@ export class PlaidService {
         for (const tx of response.data.transactions) {
           const account = accounts.find((acct) => acct.plaidAccountId === tx.account_id);
           if (!account) continue;
-          const rawPayload = tx as unknown as Prisma.InputJsonValue;
+          const rawPayload = this.rawPayloads.encrypt(tx);
           await this.prisma.transactionRaw.upsert({
             where: { bankTransactionId: tx.transaction_id },
             update: {

src/teller/teller.service.ts

@@ -4,6 +4,7 @@ import * as fs from "fs";
 import * as https from "https";
 import { PrismaService } from "../prisma/prisma.service";
 import { EncryptionService } from "../common/encryption.service";
+import { RawPayloadEncryptionService } from "../common/raw-payload-encryption.service";
 import { PlanLimitsService } from "../stripe/plan-limits.service";
 import { TellerEnrollmentPayload } from "./teller.controller";
 
@@ -15,6 +16,7 @@ export class TellerService {
     private readonly prisma: PrismaService,
     private readonly encryption: EncryptionService,
     private readonly planLimits: PlanLimitsService,
+    private readonly rawPayloads: RawPayloadEncryptionService,
   ) {}
 
   getConnectConfig() {
@@ -117,7 +119,7 @@ export class TellerService {
               date: new Date(tx.date),
               amount: new Prisma.Decimal(tx.amount),
               description: tx.description ?? "Teller transaction",
-              rawPayload: tx as unknown as Prisma.InputJsonValue,
+              rawPayload: this.rawPayloads.encrypt(tx),
               source: "teller",
               ingestedAt: new Date(),
             },
@@ -127,7 +129,7 @@ export class TellerService {
               date: new Date(tx.date),
               amount: new Prisma.Decimal(tx.amount),
               description: tx.description ?? "Teller transaction",
-              rawPayload: tx as unknown as Prisma.InputJsonValue,
+              rawPayload: this.rawPayloads.encrypt(tx),
               source: "teller",
             },
           });

src/transactions/transactions.service.ts

@@ -5,6 +5,7 @@ import { Prisma } from "@prisma/client";
 import { PrismaService } from "../prisma/prisma.service";
 import { PlaidService } from "../plaid/plaid.service";
 import { OpaqueIdService } from "../common/opaque-id.service";
+import { RawPayloadEncryptionService } from "../common/raw-payload-encryption.service";
 import { ViewRefService } from "../common/view-ref.service";
 import { ExportsService } from "../exports/exports.service";
 import { UpdateDerivedDto } from "./dto/update-derived.dto";
@@ -155,6 +156,7 @@ export class TransactionsService {
     private readonly plaidService: PlaidService,
     private readonly opaqueIds: OpaqueIdService,
     private readonly viewRefs: ViewRefService,
+    private readonly rawPayloads: RawPayloadEncryptionService,
     private readonly exportsService?: ExportsService,
   ) {}
 
@@ -351,7 +353,7 @@ export class TransactionsService {
             date: dateObj,
             amount: row.amount,
             description: row.description,
-            rawPayload: row as unknown as Prisma.InputJsonValue,
+            rawPayload: this.rawPayloads.encrypt(row),
             ingestedAt: new Date(),
             source: "csv",
           },
@@ -456,7 +458,7 @@ export class TransactionsService {
         date: new Date(payload.date),
         amount: payload.amount,
         description: payload.description,
-        rawPayload: payload as unknown as Prisma.InputJsonValue,
+        rawPayload: this.rawPayloads.encrypt(payload),
         ingestedAt: new Date(),
         source: "manual",
       },

test/plaid.webhook.spec.ts

@@ -25,6 +25,9 @@ const createService = () => {
     encryption: {
       decrypt: jest.fn((value: string) => value.replace("enc_", "raw_")),
     },
+    rawPayloads: {
+      encrypt: jest.fn((payload: unknown) => ({ encrypted: true, version: 1, ciphertext: JSON.stringify(payload) })),
+    },
     logger: {
       error: jest.fn(),
     },

test/raw-payload-encryption.service.spec.ts

@@ -0,0 +1,26 @@
+import { RawPayloadEncryptionService } from "../src/common/raw-payload-encryption.service";
+
+describe("RawPayloadEncryptionService", () => {
+  it("stores raw transaction payloads as encrypted envelopes", () => {
+    const encryption = {
+      encrypt: jest.fn((value: string) => `cipher:${Buffer.from(value).toString("base64")}`),
+      decrypt: jest.fn((value: string) => Buffer.from(value.replace("cipher:", ""), "base64").toString("utf8")),
+    };
+    const service = new RawPayloadEncryptionService(encryption as never);
+
+    const encrypted = service.encrypt({ transaction_id: "tx_1", merchant: "Coffee" }) as {
+      encrypted: boolean;
+      version: number;
+      ciphertext: string;
+      transaction_id?: string;
+    };
+
+    expect(encrypted).toEqual({
+      encrypted: true,
+      version: 1,
+      ciphertext: expect.stringMatching(/^cipher:/),
+    });
+    expect(encrypted).not.toHaveProperty("transaction_id");
+    expect(service.decrypt(encrypted)).toEqual({ transaction_id: "tx_1", merchant: "Coffee" });
+  });
+});

test/teller.service.spec.ts

@@ -18,6 +18,9 @@ const createService = () => {
       encrypt: jest.fn((value: string) => `enc_${value}`),
       decrypt: jest.fn((value: string) => value.replace("enc_", "")),
     },
+    rawPayloads: {
+      encrypt: jest.fn((payload: unknown) => ({ encrypted: true, version: 1, ciphertext: JSON.stringify(payload) })),
+    },
     logger: {
       warn: jest.fn(),
     },

test/transactions.service.spec.ts

@@ -10,9 +10,10 @@ const createService = () => {
     decode: jest.fn((_kind: string, _userId: string, token: string) => token.replace(/^opaque_[^_]+_/, "")),
   };
   const viewRefs = { matches: jest.fn() };
+  const rawPayloads = { encrypt: jest.fn((payload: unknown) => ({ encrypted: true, version: 1, ciphertext: JSON.stringify(payload) })) };
   const exportsService = { syncGoogleSheets: jest.fn().mockResolvedValue({ status: "synced" }) };
-  const service = new TransactionsService(prisma as any, plaid as any, opaqueIds as any, viewRefs as any, exportsService as any);
+  const service = new TransactionsService(prisma as any, plaid as any, opaqueIds as any, viewRefs as any, rawPayloads as any, exportsService as any);
-  return { service, prisma, plaid, opaqueIds, viewRefs, exportsService };
+  return { service, prisma, plaid, opaqueIds, viewRefs, rawPayloads, exportsService };
 };
 
 describe("TransactionsService", () => {