Remove frame-size restrictions. Issue #42

Author: SalusaSecondus

src/main/java/com/amazonaws/encryptionsdk/AwsCrypto.java

@@ -137,11 +137,7 @@ public void setEncryptionFrameSize(final int frameSize) {
         if (frameSize < 0) {
             throw new IllegalArgumentException("frameSize must be non-negative");
         }
-        if (frameSize % 16 != 0) {
-            // For compatibility reasons we'll still enforce this restriction for now.
-            // TODO: Investigate whether this can be removed.
-            throw new IllegalArgumentException("frameSize must be a multiple of 16");
-        }
+
         encryptionFrameSize_ = frameSize;
     }
 

src/test/java/com/amazonaws/encryptionsdk/AwsCryptoTest.java

@@ -145,9 +145,7 @@ private void doEncryptDecryptWithParsedCiphertext(final int byteSize, final int
     @Test
     public void encryptDecrypt() {
         for (final CryptoAlgorithm cryptoAlg : EnumSet.allOf(CryptoAlgorithm.class)) {
-            final int blockSize = cryptoAlg.getBlockSize();
-            final int[] frameSizeToTest = { 0, blockSize, blockSize * 2, blockSize * 10,
-                    AwsCrypto.getDefaultFrameSize() };
+            final int[] frameSizeToTest = TestUtils.getFrameSizesToTest(cryptoAlg);
 
             for (int i = 0; i < frameSizeToTest.length; i++) {
                 final int frameSize = frameSizeToTest[i];
@@ -175,9 +173,7 @@ public void encryptDecryptWithBadSignature() {
             if (cryptoAlg.getTrailingSignatureAlgo() == null) {
                 continue;
             }
-            final int blockSize = cryptoAlg.getBlockSize();
-            final int[] frameSizeToTest = { 0, blockSize, blockSize * 2, blockSize * 10,
-                    AwsCrypto.getDefaultFrameSize() };
+            final int[] frameSizeToTest = TestUtils.getFrameSizesToTest(cryptoAlg);
 
             for (int i = 0; i < frameSizeToTest.length; i++) {
                 final int frameSize = frameSizeToTest[i];
@@ -202,9 +198,7 @@ public void encryptDecryptWithBadSignature() {
     @Test
     public void encryptDecryptWithParsedCiphertext() {
         for (final CryptoAlgorithm cryptoAlg : EnumSet.allOf(CryptoAlgorithm.class)) {
-            final int blockSize = cryptoAlg.getBlockSize();
-            final int[] frameSizeToTest = { 0, blockSize, blockSize * 2, blockSize * 10,
-                    AwsCrypto.getDefaultFrameSize() };
+            final int[] frameSizeToTest = TestUtils.getFrameSizesToTest(cryptoAlg);
 
             for (int i = 0; i < frameSizeToTest.length; i++) {
                 final int frameSize = frameSizeToTest[i];
@@ -336,9 +330,7 @@ private void doEstimateCiphertextSize(final CryptoAlgorithm cryptoAlg, final int
     @Test
     public void estimateCiphertextSize() {
         for (final CryptoAlgorithm cryptoAlg : EnumSet.allOf(CryptoAlgorithm.class)) {
-            final int blockSize = cryptoAlg.getBlockSize();
-            final int[] frameSizeToTest = { 0, blockSize, blockSize * 2, blockSize * 10,
-                    AwsCrypto.getDefaultFrameSize() };
+            final int[] frameSizeToTest = TestUtils.getFrameSizesToTest(cryptoAlg);
 
             for (int i = 0; i < frameSizeToTest.length; i++) {
                 final int frameSize = frameSizeToTest[i];
@@ -664,10 +656,12 @@ public void setValidFrameSize() throws IOException {
         assertEquals(setFrameSize, getFrameSize);
     }
 
-    @Test(expected = IllegalArgumentException.class)
-    public void unalignedFrameSizesAreRejected() throws IOException {
+
+    public void unalignedFrameSizesAreAccepted() throws IOException {
         final int frameSize = AwsCrypto.getDefaultCryptoAlgorithm().getBlockSize() - 1;
         encryptionClient_.setEncryptionFrameSize(frameSize);
+
+        assertEquals(frameSize, encryptionClient_.getEncryptionFrameSize());
     }
 
     @Test(expected = IllegalArgumentException.class)

src/test/java/com/amazonaws/encryptionsdk/CryptoInputStreamTest.java

@@ -158,11 +158,7 @@ public static Collection<Object[]> encryptDecryptParams() {
             boolean firstAlgorithm = true;
 
             for (final CryptoAlgorithm cryptoAlg : EnumSet.allOf(CryptoAlgorithm.class)) {
-                final int blockSize = cryptoAlg.getBlockSize();
-                final int[] frameSizeToTest = {
-                        0, blockSize, blockSize * 2, blockSize * 10,
-                        AwsCrypto.getDefaultFrameSize()
-                };
+                final int[] frameSizeToTest = TestUtils.getFrameSizesToTest(cryptoAlg);
 
                 // Our bytesToTest and readLenVals arrays tend to have the bigger numbers towards the end - we'll chop off
                 // the last few as they take the longest and don't really add that much more coverage.

src/test/java/com/amazonaws/encryptionsdk/CryptoOutputStreamTest.java

@@ -155,9 +155,7 @@ public static Collection<Object[]> encryptDecryptParams() {
             ArrayList<Object[]> cases = new ArrayList<>();
 
             for (final CryptoAlgorithm cryptoAlg : EnumSet.allOf(CryptoAlgorithm.class)) {
-                final int blockSize = cryptoAlg.getBlockSize();
-                final int[] frameSizeToTest = { 0, blockSize, blockSize * 2, blockSize * 10,
-                                                AwsCrypto.getDefaultFrameSize() };
+              final int[] frameSizeToTest = TestUtils.getFrameSizesToTest(cryptoAlg);
 
                 // iterate over frame size to test
                 for (int i = 0; i < frameSizeToTest.length; i++) {

src/test/java/com/amazonaws/encryptionsdk/TestUtils.java

@@ -159,4 +159,19 @@ public static byte[] insecureRandomBytes(int length) {
     public static ByteArrayInputStream insecureRandomStream(int length) {
         return new ByteArrayInputStream(ensureRandomCached(length), 0, length);
     }
+
+    public static int[] getFrameSizesToTest(final CryptoAlgorithm cryptoAlg) {
+      final int blockSize = cryptoAlg.getBlockSize();
+      final int[] frameSizeToTest = {
+          0,
+          blockSize - 1,
+          blockSize,
+          blockSize + 1,
+          blockSize * 2,
+          blockSize * 10,
+          blockSize * 10 + 1,
+          AwsCrypto.getDefaultFrameSize()
+      };
+      return frameSizeToTest;
+  }
 }