- file name encryption is deterministic again (broken by fix for #7)

- improved unit test to avoid this mistake in the future

main/crypto-aes/src/main/java/org/cryptomator/crypto/aes256/Aes256Cryptor.java

@@ -300,13 +300,13 @@ public class Aes256Cryptor extends AbstractCryptor implements AesCryptographicCo
 	 * {@link FileNamingConventions#LONG_NAME_FILE_EXT}.
 	 */
 	private String encryptPathComponent(final String cleartext, final SecretKey key, CryptorIOSupport ioSupport) throws IllegalBlockSizeException, BadPaddingException, IOException {
-		final byte[] ivRandomPart = randomData(FILE_NAME_IV_LENGTH);
+		final long cleartextHash = crc32Sum(cleartext.getBytes());
 		final ByteBuffer iv = ByteBuffer.allocate(AES_BLOCK_LENGTH);
-		iv.put(ivRandomPart);
+		iv.putLong(cleartextHash);
 		final Cipher cipher = this.cipher(FILE_NAME_CIPHER, key, iv.array(), Cipher.ENCRYPT_MODE);
 		final byte[] cleartextBytes = cleartext.getBytes(Charsets.UTF_8);
 		final byte[] encryptedBytes = cipher.doFinal(cleartextBytes);
-		final String ivAndCiphertext = ENCRYPTED_FILENAME_CODEC.encodeAsString(ivRandomPart) + IV_PREFIX_SEPARATOR + ENCRYPTED_FILENAME_CODEC.encodeAsString(encryptedBytes);
+		final String ivAndCiphertext = Long.toHexString(cleartextHash) + IV_PREFIX_SEPARATOR + ENCRYPTED_FILENAME_CODEC.encodeAsString(encryptedBytes);
 
 		if (ivAndCiphertext.length() + BASIC_FILE_EXT.length() > ENCRYPTED_FILENAME_LENGTH_LIMIT) {
 			final String crc32 = Long.toHexString(crc32Sum(ivAndCiphertext.getBytes()));
@@ -354,11 +354,10 @@ public class Aes256Cryptor extends AbstractCryptor implements AesCryptographicCo
 			throw new IllegalArgumentException("Unsupported path component: " + encrypted);
 		}
 
-		final String ivRandomPartStr = StringUtils.substringBefore(ivAndCiphertext, IV_PREFIX_SEPARATOR);
+		final String cleartextHash = StringUtils.substringBefore(ivAndCiphertext, IV_PREFIX_SEPARATOR);
 		final String ciphertext = StringUtils.substringAfter(ivAndCiphertext, IV_PREFIX_SEPARATOR);
-		final byte[] ivRandomPart = ENCRYPTED_FILENAME_CODEC.decode(ivRandomPartStr);
 		final ByteBuffer iv = ByteBuffer.allocate(AES_BLOCK_LENGTH);
-		iv.put(ivRandomPart);
+		iv.putLong(Long.parseLong(cleartextHash, 16));
 
 		final Cipher cipher = this.cipher(FILE_NAME_CIPHER, key, iv.array(), Cipher.DECRYPT_MODE);
 		final byte[] encryptedBytes = ENCRYPTED_FILENAME_CODEC.decode(ciphertext);

main/crypto-aes/src/test/java/org/cryptomator/crypto/aes256/Aes256CryptorTest.java

@@ -134,15 +134,19 @@ public class Aes256CryptorTest {
 
 		// short path components
 		final String originalPath1 = "foo/bar/baz";
-		final String encryptedPath1 = cryptor.encryptPath(originalPath1, '/', '/', ioSupportMock);
-		final String decryptedPath1 = cryptor.decryptPath(encryptedPath1, '/', '/', ioSupportMock);
+		final String encryptedPath1a = cryptor.encryptPath(originalPath1, '/', '/', ioSupportMock);
+		final String encryptedPath1b = cryptor.encryptPath(originalPath1, '/', '/', ioSupportMock);
+		Assert.assertEquals(encryptedPath1a, encryptedPath1b);
+		final String decryptedPath1 = cryptor.decryptPath(encryptedPath1a, '/', '/', ioSupportMock);
 		Assert.assertEquals(originalPath1, decryptedPath1);
 
 		// long path components
 		final String str50chars = "aaaaaaaaaabbbbbbbbbbccccccccccddddddddddeeeeeeeeee";
 		final String originalPath2 = "foo/" + str50chars + str50chars + str50chars + str50chars + str50chars + "/baz";
-		final String encryptedPath2 = cryptor.encryptPath(originalPath2, '/', '/', ioSupportMock);
-		final String decryptedPath2 = cryptor.decryptPath(encryptedPath2, '/', '/', ioSupportMock);
+		final String encryptedPath2a = cryptor.encryptPath(originalPath2, '/', '/', ioSupportMock);
+		final String encryptedPath2b = cryptor.encryptPath(originalPath2, '/', '/', ioSupportMock);
+		Assert.assertEquals(encryptedPath2a, encryptedPath2b);
+		final String decryptedPath2 = cryptor.decryptPath(encryptedPath2a, '/', '/', ioSupportMock);
 		Assert.assertEquals(originalPath2, decryptedPath2);
 	}