Seekable Crypto

Seekable Crypto is a Java library that provides the ability to seek within SeekableInputs while decrypting the underlying contents along with some utilities for storing and generating the keys used to encrypt/decrypt the data streams. An implementation of the Hadoop FileSystem is also included that uses the Seekable Crypto library to provide efficient and transparent client-side encryption for Hadoop filesystems.

Supported Ciphers

Currently AES/CTR/NoPadding and AES/CBC/PKCS5Padding are supported.

Disclaimer Neither supported AES mode is authenticated. Authentication should be performed by consumers of this library via an external cryptographic mechanism such as Encrypt-then-MAC. Failure to properly authenticate ciphertext breaks security in some scenarios where an attacker can manipulate ciphertext inputs.

Programatic Example

Source for examples can be found here

byte[] bytes = "0123456789".getBytes(StandardCharsets.UTF_8);

// Store this key material for future decryption
KeyMaterial keyMaterial = SeekableCipherFactory.generateKeyMaterial(AesCtrCipher.ALGORITHM);
ByteArrayOutputStream os = new ByteArrayOutputStream(bytes.length);

// Encrypt some bytes
OutputStream encryptedStream = CryptoStreamFactory.encrypt(os, keyMaterial, AesCtrCipher.ALGORITHM);
encryptedStream.write(bytes);
encryptedStream.close();
byte[] encryptedBytes = os.toByteArray();

// Bytes written to stream are encrypted
assertThat(encryptedBytes).isNotEqualTo(bytes);

SeekableInput is = new InMemorySeekableDataInput(encryptedBytes);
SeekableInput decryptedStream = CryptoStreamFactory.decrypt(is, keyMaterial, AesCtrCipher.ALGORITHM);

// Seek to the last byte in the decrypted stream and verify its decrypted value
byte[] readBytes = new byte[bytes.length];
decryptedStream.seek(bytes.length - 1);
decryptedStream.read(readBytes, 0, 1);
assertThat(readBytes[0]).isEqualTo(bytes[bytes.length - 1]);

// Seek to the beginning of the decrypted stream and verify it's equal to the raw bytes
decryptedStream.seek(0);
decryptedStream.read(readBytes, 0, bytes.length);
assertThat(readBytes).isEqualTo(bytes);

Hadoop Crypto

Hadoop Crypto is a library for per-file client-side encryption in Hadoop FileSystems such as HDFS or S3. It provides wrappers for the Hadoop FileSystem API that transparently encrypt and decrypt the underlying streams. The encryption algorithm uses Key Encapsulation: each file is encrypted with a unique symmetric key, which is itself secured with a public/private key pair and stored alongside the file.

Architecture

The EncryptedFileSystem wraps any FileSystem implementation and encrypts the streams returned by open and close. These streams are encrypted/decrypted by a unique per-file symmetric key which is then passed to the KeyStorageStrategy which stores the key for future access. The provided storage strategy implementation encrypts the symmetric key using a public/private key pair and then stores the encrypted key on the FileSystem with the encrypted file.

Standalone Example

The hadoop-crypto-all.jar can be added to the classpath of any client and used to wrap any concrete backing FileSystem. The scheme of the EncryptedFileSystem is e[FS-scheme] where [FS-scheme] is any FileSystem that can be instantiated statically using FileSystem#get (eg: efile). The FileSystem implementation, public key, and private key must be configured in the core-site.xml as well.

Hadoop Cli

Add hadoop-crypto-all.jar to the classpath of the cli (ex: share/hadoop/common).

Generate public/private keys

openssl genrsa -out rsa.key 2048
# Public Key
openssl rsa -in rsa.key -outform PEM -pubout 2>/dev/null | grep -v PUBLIC | tr -d '\r\n'
# Private Key
openssl pkcs8 -topk8 -inform pem -in rsa.key -outform pem -nocrypt | grep -v PRIVATE | tr -d '\r\n'

core-site.xml

<configuration>
    <property>
        <name>fs.efile.impl</name> <!-- others: fs.es3a.impl or fs.ehdfs.impl -->
        <value>com.palantir.crypto2.hadoop.StandaloneEncryptedFileSystem</value>
    </property>

    <property>
        <name>fs.efs.key.public</name>
        <value>MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqXkSOcB2UpLrlG3scAHDavPnSucxOwRWG12woY5JerYlqyIm7xcNuyLQ/rLPxdlCGgOZOoPzKVXc/3pAeOdPM1LcXLNW8d7Uht3vo7a6SR/mXMiCTMn+9wOx40Bq0ofvx9K4RSpW2lKrlJNUJG+RP5lO7OhB5pveEBMn/8OR2yMLgS58rHQ0nrXXUHqbWiMI8k+eYK7aimexkQDhIXtbqmQ5tAXKyoSMDAyeuDNY8WsYaW15OCwGSIRClNAiwPEGLQCYJQi41IxwQxwN42jQm7fwoVSrN4lAfi5B8EHxFglAZcE8nUTdTnXCbUk9SPz8XXmK4hmK9X4L+2Av4ucNLwIDAQAB</value>
    </property>

    <property>
        <name>fs.efs.key.private</name>
        <value>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</value>
    </property>
</configuration>

Commands

./bin/hadoop dfs -put file.txt efile:/tmp/file.txt
./bin/hadoop dfs -ls efile:/tmp
./bin/hadoop dfs -cat efile:/tmp/file.txt

Programatic Example

Source for examples can be found here

Initialization

// Get a local FileSystem
FileSystem fs = FileSystem.get(new URI("file:///"), new Configuration());

// Initialize EFS with random public/private key pair
KeyPair pair = TestKeyPairs.generateKeyPair();
KeyStorageStrategy keyStore = new FileKeyStorageStrategy(fs, pair);
EncryptedFileSystem efs = new EncryptedFileSystem(fs, keyStore);

Writing data using EFS

// Init data and local path to write to
byte[] data = "test".getBytes(StandardCharsets.UTF_8);
byte[] readData = new byte[data.length];
Path path = new Path(folder.newFile().getAbsolutePath());

// Write data out to the encrypted stream
OutputStream eos = efs.create(path);
eos.write(data);
eos.close();

// Reading through the decrypted stream produces the original bytes
InputStream ein = efs.open(path);
IOUtils.readFully(ein, readData);
assertThat(data, is(readData));

// Reading through the raw stream produces the encrypted bytes
InputStream in = fs.open(path);
IOUtils.readFully(in, readData);
assertThat(data, is(not(readData)));

// Wrapped symmetric key is stored next to the encrypted file
assertTrue(fs.exists(new Path(path + FileKeyStorageStrategy.EXTENSION)));

Hadoop Configuration Properties

Key	Value	Default
fs.efs.cipher	The cipher used to wrap the underlying streams.	AES/CTR/NoPadding
fs.e[FS-scheme].impl	Must be set to com.palantir.crypto2.hadoop.StandaloneEncryptedFileSystem
fs.efs.key.public	Base64 encoded X509 public key
fs.efs.key.private	Base64 encoded PKCS8 private key
fs.efs.key.algorithm	Public/private key pair algorithm	RSA

License

This repository is made available under the Apache 2.0 License.