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- pad filenames with NULL bytes (fixes #24)

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This commit is contained in:
Sebastian Stenzel
2015-01-16 19:55:33 +01:00
parent d774546bf8
commit 7813a11381
2 changed files with 22 additions and 3 deletions
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17
main/crypto-aes/src/main/java/org/cryptomator/crypto/aes256/Aes256Cryptor.java
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@@ -331,8 +331,11 @@ public class Aes256Cryptor extends AbstractCryptor implements AesCryptographicCo
final ByteBuffer iv = ByteBuffer.allocate(AES_BLOCK_LENGTH);
iv.put(partialIv);
final Cipher cipher = this.aesCtrCipher(key, iv.array(), Cipher.ENCRYPT_MODE);
// add NULL padding to the cleartext to get a multiple of the block size:
final byte[] cleartextBytes = cleartext.getBytes(StandardCharsets.UTF_8);
final byte[] encryptedBytes = cipher.doFinal(cleartextBytes);
final byte[] nullBytePadding = new byte[AES_BLOCK_LENGTH - cleartextBytes.length % AES_BLOCK_LENGTH];
final byte[] paddedCleartextBytes = ArrayUtils.addAll(cleartextBytes, nullBytePadding);
final byte[] encryptedBytes = cipher.doFinal(paddedCleartextBytes);
final String ivAndCiphertext = ENCRYPTED_FILENAME_CODEC.encodeAsString(partialIv) + IV_PREFIX_SEPARATOR + ENCRYPTED_FILENAME_CODEC.encodeAsString(encryptedBytes);
if (ivAndCiphertext.length() + BASIC_FILE_EXT.length() > ENCRYPTED_FILENAME_LENGTH_LIMIT) {
@@ -387,8 +390,16 @@ public class Aes256Cryptor extends AbstractCryptor implements AesCryptographicCo
final Cipher cipher = this.aesCtrCipher(key, iv.array(), Cipher.DECRYPT_MODE);
final byte[] encryptedBytes = ENCRYPTED_FILENAME_CODEC.decode(ciphertext);
final byte[] cleartextBytes = cipher.doFinal(encryptedBytes);
return new String(cleartextBytes, StandardCharsets.UTF_8);
final byte[] paddedCleartextBytes = cipher.doFinal(encryptedBytes);
// remove NULL padding (not valid in file names anyway)
final int beginOfPadding = ArrayUtils.indexOf(paddedCleartextBytes, (byte) 0x00);
if (beginOfPadding == -1) {
return new String(paddedCleartextBytes, StandardCharsets.UTF_8);
} else {
final byte[] cleartextBytes = Arrays.copyOf(paddedCleartextBytes, beginOfPadding);
return new String(cleartextBytes, StandardCharsets.UTF_8);
}
}
private LongFilenameMetadata getMetadata(CryptorIOSupport ioSupport, String metadataFile) throws IOException {

8
main/crypto-aes/src/test/java/org/cryptomator/crypto/aes256/Aes256CryptorTest.java
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@@ -235,6 +235,14 @@ public class Aes256CryptorTest {
Assert.assertEquals(encryptedPath2a, encryptedPath2b);
final String decryptedPath2 = cryptor.decryptPath(encryptedPath2a, '/', '/', ioSupportMock);
Assert.assertEquals(originalPath2, decryptedPath2);
// block size length path components
final String originalPath3 = "aaaabbbbccccdddd";
final String encryptedPath3a = cryptor.encryptPath(originalPath3, '/', '/', ioSupportMock);
final String encryptedPath3b = cryptor.encryptPath(originalPath3, '/', '/', ioSupportMock);
Assert.assertEquals(encryptedPath3a, encryptedPath3b);
final String decryptedPath3 = cryptor.decryptPath(encryptedPath3a, '/', '/', ioSupportMock);
Assert.assertEquals(originalPath3, decryptedPath3);
}
private static class CryptoIOSupportMock implements CryptorIOSupport {