Make Java API for username hashing more idiomatic

whisperfish · Feb 9, 2023 · f1b6c63 · f1b6c63
1 parent 9bd2edc
commit f1b6c63
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Showing 3 changed files with 65 additions and 24 deletions.
diff --git a/java/server/src/test/java/org/signal/libsignal/usernames/UsernamesTest.java b/java/server/src/test/java/org/signal/libsignal/usernames/UsernamesTest.java
@@ -5,29 +5,27 @@
 
 package org.signal.libsignal.usernames;
 
-import org.signal.libsignal.usernames.Username;
-
-import java.util.List;
-
 import junit.framework.TestCase;
 import org.signal.libsignal.protocol.util.Hex;
 
+import java.util.List;
+
 public class UsernamesTest extends TestCase {
 
     public void testUsernameGeneration() throws BaseUsernameException {
         String nickname = "SiGNAl";
-        List<String> usernames = Username.generateCandidates(nickname, 3, 32);
+        List<Username> usernames = Username.candidatesFrom(nickname, 3, 32);
         assertFalse("Non-zero number of usernames expected", usernames.size() == 0);
-        for (String name : usernames) {
-            assertTrue(String.format("%s does not start with %s", name, nickname), name.startsWith(nickname));
+        for (Username name : usernames) {
+            assertTrue(String.format("%s does not start with %s", name, nickname), name.getUsername().startsWith(nickname));
         }
     }
 
     public void testInvalidNicknameValidation() throws BaseUsernameException {
         List<String> invalidNicknames = List.of("hi", "way_too_long_to_be_a_reasonable_nickname", "I⍰Unicode", "s p a c e s", "0zerostart");
         for (String nickname : invalidNicknames) {
             try {
-                Username.generateCandidates(nickname, 3, 32);
+                Username.candidatesFrom(nickname, 3, 32);
                 fail(String.format("'%s' should not be considered valid", nickname));
             } catch (BaseUsernameException ex) {
                 // this is fine
@@ -38,28 +36,25 @@ public void testInvalidNicknameValidation() throws BaseUsernameException {
 
     public void testValidUsernameHashing() throws BaseUsernameException {
         String username = "he110.42";
-        byte[] hash = Username.hash(username);
+        byte[] hash = new Username(username).getHash();
         assertEquals(32, hash.length);
         assertEquals("f63f0521eb3adfe1d936f4b626b89558483507fbdb838fc554af059111cf322e", Hex.toStringCondensed(hash));
     }
 
     public void testToTheProofAndBack() throws BaseUsernameException {
-        String username = "hello_signal.42";
-        byte[] hash = Username.hash(username);
-        assertNotNull(hash);
-        byte[] randomness = new byte[32];
-        byte[] proof = Username.generateProof(username, randomness);
+        Username username = new Username("hello_signal.42");
+        assertNotNull(username.getHash());
+        byte[] proof = username.generateProof();
         assertNotNull(proof);
         assertEquals(128, proof.length);
-        Username.verifyProof(proof, hash);
+        Username.verifyProof(proof, username.getHash());
     }
 
     public void testInvalidHash() throws BaseUsernameException {
-        String username = "hello_signal.42";
-        byte[] hash = Username.hash(username);
-        byte[] proof = Username.generateProof(username, new byte[32]);
+        Username username = new Username("hello_signal.42");
+        byte[] hash = username.getHash();
+        byte[] proof = username.generateProof();
         hash[0] = 0;
-
         try {
             Username.verifyProof(proof, hash);
         } catch (BaseUsernameException ex) {
@@ -69,7 +64,7 @@ public void testInvalidHash() throws BaseUsernameException {
 
     public void testInvalidRandomness() throws BaseUsernameException {
         try {
-            Username.generateProof("valid_name.01", new byte[31]);
+            new Username("valid_name.01").generateProofWithRandomness(new byte[31]);
         } catch (Error err) {
             assertTrue(err.getMessage().contains("Failed to create proof"));
         }
@@ -79,15 +74,15 @@ public void testInvalidUsernames() throws BaseUsernameException {
         List<String> usernames = List.of("0zerostart.01", "zero.00", "short_zero.0", "short_one.1");
         for (String name : usernames) {
             try {
-                Username.hash(name);
+                new Username(name);
                 fail(String.format("'%s' should not be valid", name));
             } catch (BaseUsernameException ex) {
                 // this is fine
             }
         }
         for (String name : usernames) {
             try {
-                Username.generateProof(name, new byte[32]);
+                new Username(name).generateProof();
                 fail(String.format("'%s' should not be valid", name));
             } catch (BaseUsernameException ex) {
                 // this is fine

diff --git a/java/shared/java/org/signal/libsignal/usernames/Username.java b/java/shared/java/org/signal/libsignal/usernames/Username.java
@@ -6,24 +6,70 @@
 
 import org.signal.libsignal.internal.Native;
 
+import java.security.SecureRandom;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
 public final class Username {
+    private String value;
+    private byte[] hash;
+
+    public Username(String username) throws BaseUsernameException {
+        this.value = username;
+        this.hash = hash(username);
+    }
+
+    public String getUsername() {
+        return this.value;
+    }
+
+    public byte[] getHash() {
+        return this.hash;
+    }
+
+    public static List<Username> candidatesFrom(String nickname, int minNicknameLength, int maxNicknameLength) throws BaseUsernameException {
+        String names = Native.Username_CandidatesFrom(nickname, minNicknameLength, maxNicknameLength);
+        ArrayList<Username> result = new ArrayList<>();
+        for (String name : names.split(",")) {
+            result.add(new Username(name));
+        }
+        return result;
+    }
+
+    public byte[] generateProof() throws BaseUsernameException {
+        byte[] randomness = new byte[32];
+        SecureRandom r = new SecureRandom();
+        r.nextBytes(randomness);
+        return generateProofWithRandomness(randomness);
+    }
+
+    public byte[] generateProofWithRandomness(byte[] randomness) throws BaseUsernameException {
+        return Native.Username_Proof(this.value, randomness);
+    }
+
+    @Deprecated
     public static List<String> generateCandidates(String nickname, int minNicknameLength, int maxNicknameLength) throws BaseUsernameException {
         String names = Native.Username_CandidatesFrom(nickname, minNicknameLength, maxNicknameLength);
         return Arrays.asList(names.split(","));
     }
 
+    @Deprecated
     public static byte[] hash(String username) throws BaseUsernameException {
         return Native.Username_Hash(username);
     }
 
+    @Deprecated
     public static byte[] generateProof(String username, byte[] randomness) throws BaseUsernameException {
         return Native.Username_Proof(username, randomness);
     }
 
     public static void verifyProof(byte[] proof, byte[] hash) throws BaseUsernameException {
         Native.Username_Verify(proof, hash);
     }
+
+    @Override
+    public String toString() {
+        return this.value;
+    }
 }
diff --git a/swift/Tests/LibSignalClientTests/UsernameTests.swift b/swift/Tests/LibSignalClientTests/UsernameTests.swift
@@ -1,10 +1,10 @@
 //
-// Copyright 2021 Signal Messenger, LLC.
+// Copyright 2023 Signal Messenger, LLC.
 // SPDX-License-Identifier: AGPL-3.0-only
 //
 
 import XCTest
-@testable import LibSignalClient
+import LibSignalClient
 
 class UsernameTests: TestCaseBase {