Filter unicode characters

quartz/src/main/java/com/vitorpamplona/quartz/nip19Bech32/bech32/Bech32Util.kt

@@ -168,18 +168,20 @@ object Bech32 {
         bech32: String,
         noChecksum: Boolean = false,
     ): Triple<String, Array<Int5>, Encoding> {
+        val filteredBech32 = bech32.filter { it.code in 33..126 }
+
         var pos = 0
-        bech32.forEachIndexed { index, char ->
+        filteredBech32.forEachIndexed { index, char ->
             require(char.code in 33..126) { "invalid character $char" }
             if (char == '1') {
                 pos = index
             }
         }
 
-        val hrp = bech32.take(pos).lowercase() // strings must be lower case
+        val hrp = filteredBech32.take(pos).lowercase() // strings must be lower case
         require(hrp.length in 1..83) { "hrp must contain 1 to 83 characters" }
 
-        val data = Array(bech32.length - pos - 1) { map[bech32[pos + 1 + it].code] }
+        val data = Array(filteredBech32.length - pos - 1) { map[filteredBech32[pos + 1 + it].code] }
 
         return if (noChecksum) {
             Triple(hrp, data, Encoding.Beck32WithoutChecksum)

quartz/src/test/java/com/vitorpamplona/quartz/nip19Bech32/NIP19ParserTest.kt

@@ -21,6 +21,7 @@
 package com.vitorpamplona.quartz.nip19Bech32
 
 import com.vitorpamplona.quartz.nip01Core.tags.addressables.ATag
+import com.vitorpamplona.quartz.nip19Bech32.bech32.bechToBytes
 import com.vitorpamplona.quartz.nip19Bech32.entities.NAddress
 import com.vitorpamplona.quartz.nip19Bech32.entities.NEvent
 import com.vitorpamplona.quartz.nip19Bech32.entities.NProfile
@@ -428,4 +429,15 @@ class NIP19ParserTest {
             nevent,
         )
     }
+
+    @Test
+    fun decodeBech32WithInvisibleCharacter() {
+        val bomChar = '\uFEFF'
+        val withBom = bomChar + "nsec1lfkarc7439n4l3uahr45ej8mrjc39dd879t0ps355550dj8j9uzs3rnw24"
+
+        assertEquals(
+            "nsec1lfkarc7439n4l3uahr45ej8mrjc39dd879t0ps355550dj8j9uzs3rnw24",
+            withBom.bechToBytes().toNsec(),
+        )
+    }
 }