Amber/PATCH.MD

Amber Signer Patch – Preserve Bunker Encryption Scheme

1. Problem Statement
   Persisted bunker requests dropped their original encryption scheme (encryptionType). Whenever a pending request made a round trip through intents or storage and came back, the signer assumed NIP-44 for the response—even if the request had arrived encrypted with NIP-04. That broke compatibility with clients expecting NIP-04 and risked leaking plaintext.

2. Proposed Solution
   Extend the custom serializer for AmberBunkerRequest to write out the encryptionType field, and add a focused unit test to guarantee that a serialized/deserialized request keeps its original scheme (e.g., NIP-04 stays NIP-04).

3. Benefits

   • Restores protocol compliance and interoperability with NIP-46 clients that still rely on NIP-04.
   • Prevents accidental downgrade of encryption, preserving end-to-end confidentiality.
   • Introduces a regression test that protects the behaviour against future changes.

4. Trade-offs

   • Slightly larger JSON payloads for persisted requests (one extra field).
   • Requires maintaining the new unit test alongside future refactors.

5. Performance Implications
   Negligible: the change adds a single string field to serialized JSON and a tiny unit test; runtime cost is effectively zero.

6. If Not Implemented

   • Responses to NIP-04 sessions would remain mis-encrypted, leading to failed signing flows and possible plaintext exposure.
   • Remote clients would see Amber as non-compliant with NIP-46, eroding trust and blocking adoption.

7. Diff Summary

   • Updated app/src/main/java/com/greenart7c3/nostrsigner/models/AmberBunkerRequest.kt to serialize encryptionType.
   • Added app/src/test/java/com/greenart7c3/nostrsigner/models/AmberBunkerRequestTest.kt to assert round-trip integrity.
   • Noted the fix in AMBER-review.MD.

8. Tests

   • GRADLE_USER_HOME=$PWD/.gradle ./gradlew testFreeDebugUnitTest --tests "com.greenart7c3.nostrsigner.models.AmberBunkerRequestTest" (passes).
   • Added unit test for serialization round-trip.

// app/src/main/java/com/greenart7c3/nostrsigner/models/AmberBunkerRequest.kt
gen.writeStringField("encryptDecryptResponse", value.encryptDecryptResponse)
gen.writeStringField("encryptionType", value.encryptionType.name)

// app/src/test/java/com/greenart7c3/nostrsigner/models/AmberBunkerRequestTest.kt
@Test
fun `encryption type survives serialization`() {
    val relay = RelayUrlNormalizer.normalizeOrNull("wss://relay.example.com")
    requireNotNull(relay)
    val request = AmberBunkerRequest(
        request = BunkerRequestConnect(remoteKey = HEX_KEY, secret = "secret", permissions = null),
        localKey = HEX_KEY,
        relays = listOf(relay),
        currentAccount = "npub1test",
        nostrConnectSecret = "secret",
        closeApplication = true,
        name = "Test App",
        signedEvent = null,
        encryptDecryptResponse = null,
        encryptionType = EncryptionType.NIP04,
    )
    val json = request.toJson()
    val roundTrip = AmberBunkerRequest.mapper.readValue(json, AmberBunkerRequest::class.java)
    assertEquals(EncryptionType.NIP04, roundTrip.encryptionType)
}