From f0f25ae12ec8c3bf52fa865e60ac32682ee97a3f Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Wed, 5 Mar 2025 12:35:33 -0500
Subject: [PATCH] Use the new avatar color hash algorithm.

---
 .../conversation/colors/AvatarColorHash.kt    | 23 +++++-------
 .../securesms/database/RecipientTable.kt      |  4 +--
 .../colors/AvatarColorHashTest.kt             | 36 +++++++++++++++++++
 3 files changed, 47 insertions(+), 16 deletions(-)
 create mode 100644 app/src/test/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHashTest.kt

diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHash.kt b/app/src/main/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHash.kt
index 6f6094de27..dec8a689ba 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHash.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHash.kt
@@ -5,7 +5,9 @@
 
 package org.thoughtcrime.securesms.conversation.colors
 
+import org.signal.core.util.CryptoUtil
 import org.thoughtcrime.securesms.groups.GroupId
+import org.whispersystems.signalservice.api.push.ServiceId
 
 /**
  * Stolen from iOS. Utilizes a simple hash to map different characteristics to an avatar color index.
@@ -17,13 +19,13 @@ object AvatarColorHash {
    *
    * Uppercase is necessary here because iOS utilizes uppercase UUIDs by default.
    */
-  fun forAddress(serviceId: String?, e164: String?): AvatarColor {
-    if (!serviceId.isNullOrEmpty()) {
-      return forSeed(serviceId.toString().uppercase())
+  fun forAddress(serviceId: ServiceId?, e164: String?): AvatarColor {
+    if (serviceId != null) {
+      return forData(serviceId.toByteArray())
     }
 
     if (!e164.isNullOrEmpty()) {
-      return forSeed(e164)
+      return forData(e164.toByteArray(Charsets.UTF_8))
     }
 
     return AvatarColor.A100
@@ -33,22 +35,15 @@ object AvatarColorHash {
     return forData(group.decodedId)
   }
 
-  fun forSeed(seed: String): AvatarColor {
-    return forData(seed.toByteArray())
-  }
-
   @JvmStatic
   fun forCallLink(rootKey: ByteArray): AvatarColor {
     return forIndex(rootKey.first().toInt())
   }
 
   private fun forData(data: ByteArray): AvatarColor {
-    var hash = 0
-    for (value in data) {
-      hash = hash.rotateLeft(3) xor value.toInt()
-    }
-
-    return forIndex(hash)
+    val hash = CryptoUtil.sha256(data)
+    val firstByte: Byte = hash[0]
+    return forIndex(firstByte.toInt())
   }
 
   private fun forIndex(index: Int): AvatarColor {
diff --git a/app/src/main/java/org/thoughtcrime/securesms/database/RecipientTable.kt b/app/src/main/java/org/thoughtcrime/securesms/database/RecipientTable.kt
index 2d78545385..abdad1eb60 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/database/RecipientTable.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/database/RecipientTable.kt
@@ -4098,7 +4098,7 @@ open class RecipientTable(context: Context, databaseHelper: SignalDatabase) : Da
       PNI_COLUMN to pni?.toString(),
       PNI_SIGNATURE_VERIFIED to pniVerified.toInt(),
       STORAGE_SERVICE_ID to Base64.encodeWithPadding(StorageSyncHelper.generateKey()),
-      AVATAR_COLOR to AvatarColorHash.forAddress((aci ?: pni)?.toString(), e164).serialize()
+      AVATAR_COLOR to AvatarColorHash.forAddress((aci ?: pni), e164).serialize()
     )
 
     if (pni != null || aci != null) {
@@ -4155,7 +4155,7 @@ open class RecipientTable(context: Context, databaseHelper: SignalDatabase) : Da
       }
 
       if (isInsert) {
-        put(AVATAR_COLOR, AvatarColorHash.forAddress(contact.proto.signalAci?.toString() ?: contact.proto.signalPni?.toString(), contact.proto.e164).serialize())
+        put(AVATAR_COLOR, AvatarColorHash.forAddress(contact.proto.signalAci ?: contact.proto.signalPni, contact.proto.e164).serialize())
       }
     }
   }
diff --git a/app/src/test/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHashTest.kt b/app/src/test/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHashTest.kt
new file mode 100644
index 0000000000..9ad29fa179
--- /dev/null
+++ b/app/src/test/java/org/thoughtcrime/securesms/conversation/colors/AvatarColorHashTest.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.thoughtcrime.securesms.conversation.colors
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.signal.core.util.Base64
+import org.thoughtcrime.securesms.groups.GroupId
+import org.whispersystems.signalservice.api.push.ServiceId.ACI
+import org.whispersystems.signalservice.api.push.ServiceId.PNI
+
+class AvatarColorHashTest {
+
+  @Test
+  fun `hash test vector - ACI`() {
+    assertEquals(AvatarColor.A140, AvatarColorHash.forAddress(ACI.parseOrThrow("a025bf78-653e-44e0-beb9-deb14ba32487"), null))
+  }
+
+  @Test
+  fun `hash test vector - PNI`() {
+    assertEquals(AvatarColor.A200, AvatarColorHash.forAddress(PNI.parseOrThrow("11a175e3-fe31-4eda-87da-e0bf2a2e250b"), null))
+  }
+
+  @Test
+  fun `hash test vector - E164`() {
+    assertEquals(AvatarColor.A150, AvatarColorHash.forAddress(null, "+12135550124"))
+  }
+
+  @Test
+  fun `hash test vector - GroupId`() {
+    assertEquals(AvatarColor.A130, AvatarColorHash.forGroupId(GroupId.V2.push(Base64.decode("BwJRIdomqOSOckHjnJsknNCibCZKJFt+RxLIpa9CWJ4="))))
+  }
+}