From f7ff4da41a9be1082375f38b78807c25bb04d0b3 Mon Sep 17 00:00:00 2001
From: Bernd Schoolmann <mail@quexten.com>
Date: Wed, 1 Jan 2025 15:09:16 +0100
Subject: [PATCH] Disable legacy ciphers

---
 .../migrate-legacy-encryption.component.ts    |  5 ++-
 .../platform/abstractions/encrypt.service.ts  |  1 +
 .../encrypt.service.implementation.ts         | 39 +++++++++++++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/apps/web/src/app/key-management/migrate-encryption/migrate-legacy-encryption.component.ts b/apps/web/src/app/key-management/migrate-encryption/migrate-legacy-encryption.component.ts
index bb5a1c511c6..1bde2618521 100644
--- a/apps/web/src/app/key-management/migrate-encryption/migrate-legacy-encryption.component.ts
+++ b/apps/web/src/app/key-management/migrate-encryption/migrate-legacy-encryption.component.ts
@@ -5,6 +5,7 @@ import { FormControl, FormGroup, Validators } from "@angular/forms";
 import { firstValueFrom } from "rxjs";
 
 import { AccountService } from "@bitwarden/common/auth/abstractions/account.service";
+import { EncryptService } from "@bitwarden/common/platform/abstractions/encrypt.service";
 import { I18nService } from "@bitwarden/common/platform/abstractions/i18n.service";
 import { LogService } from "@bitwarden/common/platform/abstractions/log.service";
 import { MessagingService } from "@bitwarden/common/platform/abstractions/messaging.service";
@@ -40,6 +41,7 @@ export class MigrateFromLegacyEncryptionComponent {
     private toastService: ToastService,
     private dialogService: DialogService,
     private folderApiService: FolderApiServiceAbstraction,
+    private encryptService: EncryptService,
   ) {}
 
   submit = async () => {
@@ -60,9 +62,10 @@ export class MigrateFromLegacyEncryptionComponent {
     const masterPassword = this.formGroup.value.masterPassword;
 
     try {
+      this.encryptService.setLegacyCiphersEnabled(true);
       await this.syncService.fullSync(false, true);
-
       await this.keyRotationService.rotateUserKeyAndEncryptedData(masterPassword, activeUser);
+      this.encryptService.setLegacyCiphersEnabled(false);
 
       this.toastService.showToast({
         variant: "success",
diff --git a/libs/common/src/platform/abstractions/encrypt.service.ts b/libs/common/src/platform/abstractions/encrypt.service.ts
index 5b28b98803b..461e8c16e8b 100644
--- a/libs/common/src/platform/abstractions/encrypt.service.ts
+++ b/libs/common/src/platform/abstractions/encrypt.service.ts
@@ -35,4 +35,5 @@ export abstract class EncryptService {
     value: string | Uint8Array,
     algorithm: "sha1" | "sha256" | "sha512",
   ): Promise<string>;
+  abstract setLegacyCiphersEnabled(enabled: boolean): void;
 }
diff --git a/libs/common/src/platform/services/cryptography/encrypt.service.implementation.ts b/libs/common/src/platform/services/cryptography/encrypt.service.implementation.ts
index 0a85b34eba8..6525ab63e00 100644
--- a/libs/common/src/platform/services/cryptography/encrypt.service.implementation.ts
+++ b/libs/common/src/platform/services/cryptography/encrypt.service.implementation.ts
@@ -14,6 +14,8 @@ import { EncryptedObject } from "../../models/domain/encrypted-object";
 import { SymmetricCryptoKey } from "../../models/domain/symmetric-crypto-key";
 
 export class EncryptServiceImplementation implements EncryptService {
+  private legacyCiphersEnabled: boolean = false;
+
   constructor(
     protected cryptoFunctionService: CryptoFunctionService,
     protected logService: LogService,
@@ -29,6 +31,14 @@ export class EncryptServiceImplementation implements EncryptService {
       return Promise.resolve(null);
     }
 
+    if (
+      !this.legacyCiphersEnabled &&
+      (key.encType === EncryptionType.AesCbc128_HmacSha256_B64 ||
+        key.encType === EncryptionType.AesCbc256_B64)
+    ) {
+      throw new Error("Legacy ciphers are disabled.");
+    }
+
     let plainBuf: Uint8Array;
     if (typeof plainValue === "string") {
       plainBuf = Utils.fromUtf8ToArray(plainValue);
@@ -48,6 +58,14 @@ export class EncryptServiceImplementation implements EncryptService {
       throw new Error("No encryption key provided.");
     }
 
+    if (
+      !this.legacyCiphersEnabled &&
+      (key.encType === EncryptionType.AesCbc128_HmacSha256_B64 ||
+        key.encType === EncryptionType.AesCbc256_B64)
+    ) {
+      throw new Error("Legacy ciphers are disabled.");
+    }
+
     const encValue = await this.aesEncrypt(plainValue, key);
     let macLen = 0;
     if (encValue.mac != null) {
@@ -76,6 +94,14 @@ export class EncryptServiceImplementation implements EncryptService {
 
     key = this.resolveLegacyKey(key, encString);
 
+    if (
+      (!this.legacyCiphersEnabled || encString.mac == null) &&
+      (key.encType === EncryptionType.AesCbc128_HmacSha256_B64 ||
+        key.encType === EncryptionType.AesCbc256_B64)
+    ) {
+      throw new Error("Legacy ciphers are disabled.");
+    }
+
     // DO NOT REMOVE OR MOVE. This prevents downgrade to mac-less CBC, which would compromise integrity and confidentiality.
     if (key.macKey != null && encString?.mac == null) {
       this.logService.error(
@@ -139,6 +165,14 @@ export class EncryptServiceImplementation implements EncryptService {
 
     key = this.resolveLegacyKey(key, encThing);
 
+    if (
+      (!this.legacyCiphersEnabled || encThing.macBytes == null) &&
+      (key.encType === EncryptionType.AesCbc128_HmacSha256_B64 ||
+        key.encType === EncryptionType.AesCbc256_B64)
+    ) {
+      throw new Error("Legacy ciphers are disabled.");
+    }
+
     // DO NOT REMOVE OR MOVE. This prevents downgrade to mac-less CBC, which would compromise integrity and confidentiality.
     if (key.macKey != null && encThing.macBytes == null) {
       this.logService.error(
@@ -297,4 +331,9 @@ export class EncryptServiceImplementation implements EncryptService {
 
     return key;
   }
+
+  setLegacyCiphersEnabled(enabled: boolean): void {
+    this.logService.info("[Encrypt service] Legacy ciphers enabled: " + enabled);
+    this.legacyCiphersEnabled = enabled;
+  }
 }