crypto: Replace cryptoMode with DeviceIsolationMode concept (#4429)

* crypto: Replace cryptoMode with DeviceIsolationMode concept

* use enum instead of string for the IsolationMode kind

* Code review - Cleaning, renaming

* review: unneeded @see in doc

* review: Rename IsolationMode with better names

* review: quick cleaning and doc

src/rust-crypto/rust-crypto.ts

@@ -45,7 +45,6 @@ import {
     CrossSigningStatus,
     CryptoApi,
     CryptoCallbacks,
-    CryptoMode,
     Curve25519AuthData,
     DecryptionFailureCode,
     DeviceVerificationStatus,
@@ -61,6 +60,9 @@ import {
     VerificationRequest,
     encodeRecoveryKey,
     deriveRecoveryKeyFromPassphrase,
+    DeviceIsolationMode,
+    AllDevicesIsolationMode,
+    DeviceIsolationModeKind,
 } from "../crypto-api/index.ts";
 import { deviceKeysToDeviceMap, rustDeviceToJsDevice } from "./device-converter.ts";
 import { IDownloadKeyResult, IQueryKeysRequest } from "../client.ts";
@@ -107,7 +109,7 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
     private readonly RECOVERY_KEY_DERIVATION_ITERATIONS = 500000;
 
     private _trustCrossSignedDevices = true;
-    private cryptoMode = CryptoMode.Legacy;
+    private deviceIsolationMode: DeviceIsolationMode = new AllDevicesIsolationMode(false);
 
     /** whether {@link stop} has been called */
     private stopped = false;
@@ -259,7 +261,7 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
             // through decryptEvent and hence get rid of this case.
             throw new Error("to-device event was not decrypted in preprocessToDeviceMessages");
         }
-        return await this.eventDecryptor.attemptEventDecryption(event, this.cryptoMode);
+        return await this.eventDecryptor.attemptEventDecryption(event, this.deviceIsolationMode);
     }
 
     /**
@@ -370,10 +372,10 @@ export class RustCrypto extends TypedEventEmitter<RustCryptoEvents, RustCryptoEv
     }
 
     /**
-     * Implementation of {@link Crypto.CryptoApi#setCryptoMode}.
+     * Implementation of {@link CryptoApi#setDeviceIsolationMode}.
      */
-    public setCryptoMode(cryptoMode: CryptoMode): void {
-        this.cryptoMode = cryptoMode;
+    public setDeviceIsolationMode(isolationMode: DeviceIsolationMode): void {
+        this.deviceIsolationMode = isolationMode;
     }
 
     /**
@@ -1776,7 +1778,10 @@ class EventDecryptor {
         private readonly perSessionBackupDownloader: PerSessionKeyBackupDownloader,
     ) {}
 
-    public async attemptEventDecryption(event: MatrixEvent, cryptoMode: CryptoMode): Promise<IEventDecryptionResult> {
+    public async attemptEventDecryption(
+        event: MatrixEvent,
+        isolationMode: DeviceIsolationMode,
+    ): Promise<IEventDecryptionResult> {
         // add the event to the pending list *before* attempting to decrypt.
         // then, if the key turns up while decryption is in progress (and
         // decryption fails), we will schedule a retry.
@@ -1784,16 +1789,14 @@ class EventDecryptor {
         this.addEventToPendingList(event);
 
         let trustRequirement;
-        switch (cryptoMode) {
-            case CryptoMode.Legacy:
+
+        switch (isolationMode.kind) {
+            case DeviceIsolationModeKind.AllDevicesIsolationMode:
                 trustRequirement = RustSdkCryptoJs.TrustRequirement.Untrusted;
                 break;
-            case CryptoMode.Transition:
+            case DeviceIsolationModeKind.OnlySignedDevicesIsolationMode:
                 trustRequirement = RustSdkCryptoJs.TrustRequirement.CrossSignedOrLegacy;
                 break;
-            case CryptoMode.Invisible:
-                trustRequirement = RustSdkCryptoJs.TrustRequirement.CrossSigned;
-                break;
         }
 
         try {