From b0f538525a2a6a55f0aeaf75fba33bb75d9170c7 Mon Sep 17 00:00:00 2001
From: Oscar Mira <valldrac@molly.im>
Date: Sun, 9 Feb 2020 12:46:49 +0100
Subject: [PATCH] Fix MemoryCost minimum value according to specs

---
 .../org/signal/argon2/Argon2BuilderTest.java  | 20 ++++++++++++++++++-
 .../java/org/signal/argon2/Argon2Test.java    | 12 -----------
 .../main/java/org/signal/argon2/Argon2.java   |  4 ++--
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/android/argon2/src/androidTest/java/org/signal/argon2/Argon2BuilderTest.java b/android/argon2/src/androidTest/java/org/signal/argon2/Argon2BuilderTest.java
index b2af77f..9a77268 100644
--- a/android/argon2/src/androidTest/java/org/signal/argon2/Argon2BuilderTest.java
+++ b/android/argon2/src/androidTest/java/org/signal/argon2/Argon2BuilderTest.java
@@ -16,7 +16,7 @@ import static org.signal.argon2.Type.Argon2id;
 public final class Argon2BuilderTest {
 
   @Test
-  public void memory_too_low() {
+  public void memory_negative() {
     Argon2.Builder builder = new Argon2.Builder(Version.LATEST)
                                        .type(Argon2id);
 
@@ -24,6 +24,24 @@ public final class Argon2BuilderTest {
       .isExactlyInstanceOf(IllegalArgumentException.class);
   }
 
+  @Test
+  public void memory_too_low() {
+    Argon2.Builder builder = new Argon2.Builder(Version.LATEST)
+                                       .type(Argon2id);
+
+    assertThatThrownBy(() -> builder.memoryCostKiB(7))
+      .isExactlyInstanceOf(IllegalArgumentException.class);
+
+  }
+
+  @Test
+  public void memory_too_low_for_parallelism() {
+    Argon2.Builder builder = new Argon2.Builder(Version.LATEST)
+                                       .type(Argon2id);
+    assertThatThrownBy(() -> builder.memoryCostKiB(8).parallelism(2).build())
+      .isExactlyInstanceOf(IllegalArgumentException.class);
+  }
+
   @Test
   public void memory_too_high() {
     Argon2.Builder builder = new Argon2.Builder(Version.LATEST)
diff --git a/android/argon2/src/androidTest/java/org/signal/argon2/Argon2Test.java b/android/argon2/src/androidTest/java/org/signal/argon2/Argon2Test.java
index ba8a4df..3203026 100644
--- a/android/argon2/src/androidTest/java/org/signal/argon2/Argon2Test.java
+++ b/android/argon2/src/androidTest/java/org/signal/argon2/Argon2Test.java
@@ -222,18 +222,6 @@ public final class Argon2Test {
       ascii("password"), Argon2i));
   }
 
-  @Test
-  public void memory_too_little() {
-    Argon2 argon2 = new Argon2.Builder(Version.LATEST)
-                              .type(Argon2id)
-                              .memoryCostOrder(2)
-                              .build();
-
-    assertThatThrownBy(() -> argon2.hash(ascii("password"), ascii("diffsalt")))
-      .isExactlyInstanceOf(Argon2Exception.class)
-      .hasMessageContaining("Memory cost is too small");
-  }
-
   @Test
   public void salt_too_short() {
     Argon2 argon2 = new Argon2.Builder(Version.LATEST)
diff --git a/android/argon2/src/main/java/org/signal/argon2/Argon2.java b/android/argon2/src/main/java/org/signal/argon2/Argon2.java
index 4a64d9d..4ee3756 100644
--- a/android/argon2/src/main/java/org/signal/argon2/Argon2.java
+++ b/android/argon2/src/main/java/org/signal/argon2/Argon2.java
@@ -92,8 +92,7 @@ public final class Argon2 {
      * Sets the memory usage of {@param kib} KiB.
      */
     public Builder memoryCostKiB(int kib) {
-      if (kib      < 4) throw new IllegalArgumentException("kib too small, minimum 4");
-      if (kib % 4 != 0) throw new IllegalArgumentException("kib must be multiple of 4");
+      if (kib < 8) throw new IllegalArgumentException("kib too small, minimum 8");
       this.mCostKiB = kib;
       return this;
     }
@@ -130,6 +129,7 @@ public final class Argon2 {
     }
 
     public Argon2 build() {
+      if (mCostKiB < (8 * parallelism)) throw new IllegalArgumentException("memory cost too small for given value of parallelism");
       return new Argon2(this);
     }
   }