io.ably.lib.util

Class Crypto

java.lang.Object

io.ably.lib.util.Crypto

public class Crypto
extends java.lang.Object

Utility classes and interfaces for message payload encryption. This class supports AES/CBC/PKCS5 with a default key length of 128 bits but supporting other key lengths. Other algorithms and chaining modes are not supported directly, but supportable by extending/implementing the base classes and interfaces here. Secure random data for creation of Initialisation Vectors (IVs) and keys is obtained from the default system SecureRandom. Future extensions of this class might make the SecureRandom pluggable or at least seedable with client-provided entropy. Each message payload is encrypted with an IV in CBC mode, and the IV is concatenated with the resulting raw ciphertext to construct the "ciphertext" data passed to the recipient.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Crypto.ChannelCipher Interface for a ChannelCipher instance that may be associated with a Channel.
static class	Crypto.CipherParams A class encapsulating the client-specifiable parameters for the cipher.

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	DEFAULT_ALGORITHM
static int	DEFAULT_BLOCKLENGTH
static int	DEFAULT_KEYLENGTH

Constructor Summary

Constructors

Constructor and Description
Crypto()

Method Summary

Modifier and Type	Method and Description
static Crypto.ChannelCipher	getCipher(ChannelOptions opts) Internal; get a ChannelCipher instance based on the given ChannelOptions
static Crypto.CipherParams	getDefaultParams() Obtain a default CipherParams.
static Crypto.CipherParams	getDefaultParams(byte[] key) Obtain a default CipherParams.
static Crypto.CipherParams	getParams(java.lang.String algorithm, byte[] key)
static Crypto.CipherParams	getParams(java.lang.String algorithm, int keyLength)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_ALGORITHM

public static final java.lang.String DEFAULT_ALGORITHM

See Also:

Constant Field Values

DEFAULT_KEYLENGTH

public static final int DEFAULT_KEYLENGTH

See Also:

Constant Field Values

DEFAULT_BLOCKLENGTH

public static final int DEFAULT_BLOCKLENGTH

See Also:

Constant Field Values

Constructor Detail

Crypto

public Crypto()

Method Detail

getDefaultParams

public static Crypto.CipherParams getDefaultParams()

Obtain a default CipherParams. This uses default algorithm, mode and padding and key length. A key and IV are generated using the default system SecureRandom; the key may be obtained from the returned CipherParams for out-of-band distribution to other clients.

Returns:

the CipherParams

getDefaultParams

public static Crypto.CipherParams getDefaultParams(byte[] key)

Obtain a default CipherParams. This uses default algorithm, mode and padding and initialises a key based on the given key data. The cipher key length is derived from the length of the given key data. An IV is generated using the default system SecureRandom. Use this method of constructing CipherParams if initialising a Channel with a client-provided key, or to obtain a system-generated key of a non-default key length.

Returns:

the CipherParams

getParams

public static Crypto.CipherParams getParams(java.lang.String algorithm,
                                            int keyLength)

getParams

public static Crypto.CipherParams getParams(java.lang.String algorithm,
                                            byte[] key)
                                     throws java.security.NoSuchAlgorithmException

Throws:

java.security.NoSuchAlgorithmException

getCipher

public static Crypto.ChannelCipher getCipher(ChannelOptions opts)
                                      throws AblyException

Internal; get a ChannelCipher instance based on the given ChannelOptions

Parameters:

opts -

Returns:

Throws:

AblyException