Adds NIP49 to login and back up key screens

quartz/src/main/java/com/vitorpamplona/quartz/crypto/CryptoUtils.kt

@@ -21,6 +21,7 @@
 package com.vitorpamplona.quartz.crypto
 
 import android.util.Log
+import com.vitorpamplona.quartz.encoders.HexKey
 import com.vitorpamplona.quartz.events.Event
 import fr.acinq.secp256k1.Secp256k1
 import java.security.MessageDigest
@@ -34,6 +35,7 @@ object CryptoUtils {
     private val nip04 = Nip04(secp256k1, random)
     private val nip44v1 = Nip44v1(secp256k1, random)
     private val nip44v2 = Nip44v2(secp256k1, random)
+    private val nip49 = Nip49(secp256k1, random)
 
     fun clearCache() {
         nip04.clearCache()
@@ -262,6 +264,21 @@ object CryptoUtils {
         }
     }
 
+    fun decryptNIP49(
+        payload: String,
+        password: String,
+    ): String? {
+        if (payload.isEmpty() || password.isEmpty()) return null
+        return nip49.decrypt(payload, password)
+    }
+
+    fun encryptNIP49(
+        key: HexKey,
+        password: String,
+    ): String? {
+        return nip49.encrypt(key, password, 16, Nip49.EncryptedInfo.CLIENT_DOES_NOT_TRACK)
+    }
+
     class EncryptedInfoString(
         val ciphertext: String,
         val nonce: String,

quartz/src/main/java/com/vitorpamplona/quartz/crypto/Nip49.kt

@@ -39,14 +39,14 @@ class Nip49(val secp256k1: Secp256k1, val random: SecureRandom) {
     fun decrypt(
         nCryptSec: String,
         password: String,
-    ): HexKey? {
+    ): HexKey {
         return decrypt(EncryptedInfo.decodePayload(nCryptSec), password)
     }
 
     fun decrypt(
         encryptedInfo: EncryptedInfo?,
         password: String = "",
-    ): String? {
+    ): String {
         check(encryptedInfo != null) { "Couldn't decode key" }
         check(encryptedInfo.version == EncryptedInfo.V) { "invalid version" }
 
@@ -66,6 +66,8 @@ class Nip49(val secp256k1: Secp256k1, val random: SecureRandom) {
             key,
         )
 
+        check(m.any { it > 0 }) { "Incorrect password" }
+
         return m.toHexKey()
     }
 
@@ -129,9 +131,9 @@ class Nip49(val secp256k1: Secp256k1, val random: SecureRandom) {
         companion object {
             const val V: Byte = 0x02
 
-            const val UNSAFE_HANDLING = 0x00
-            const val SAFE_HANDLING = 0x01
-            const val CLIENT_DOES_NOT_TRACK = 0x02
+            const val UNSAFE_HANDLING: Byte = 0x00
+            const val SAFE_HANDLING: Byte = 0x01
+            const val CLIENT_DOES_NOT_TRACK: Byte = 0x02
 
             fun decodePayload(nCryptSec: String): EncryptedInfo? {
                 val byteArray =