org.whispersystems.libsignal.groups

Class GroupCipher

java.lang.Object

org.whispersystems.libsignal.groups.GroupCipher

public class GroupCipher
extends java.lang.Object

The main entry point for Signal Protocol group encrypt/decrypt operations. Once a session has been established with GroupSessionBuilder and a SenderKeyDistributionMessage has been distributed to each member of the group, this class can be used for all subsequent encrypt/decrypt operations within that session (ie: until group membership changes).

Constructor Summary

Constructors

Constructor and Description
GroupCipher(SenderKeyStore senderKeyStore, SenderKeyName senderKeyId)

Method Summary

Modifier and Type	Method and Description
byte[]	decrypt(byte[] senderKeyMessageBytes) Decrypt a SenderKey group message.
byte[]	decrypt(byte[] senderKeyMessageBytes, DecryptionCallback callback) Decrypt a SenderKey group message.
byte[]	encrypt(byte[] paddedPlaintext) Encrypt a message.

Methods inherited from class java.lang.Object

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

Constructor Detail

GroupCipher

public GroupCipher(SenderKeyStore senderKeyStore,
                   SenderKeyName senderKeyId)

Method Detail

encrypt

public byte[] encrypt(byte[] paddedPlaintext)
               throws NoSessionException

Encrypt a message.

Parameters:

paddedPlaintext - The plaintext message bytes, optionally padded.

Returns:

Ciphertext.

Throws:

NoSessionException

decrypt

public byte[] decrypt(byte[] senderKeyMessageBytes)
               throws LegacyMessageException,
                      DuplicateMessageException,
                      InvalidMessageException,
                      NoSessionException

Decrypt a SenderKey group message.

Parameters:

senderKeyMessageBytes - The received ciphertext.

Returns:

Plaintext

Throws:

LegacyMessageException

InvalidMessageException

DuplicateMessageException

NoSessionException

decrypt

public byte[] decrypt(byte[] senderKeyMessageBytes,
                      DecryptionCallback callback)
               throws LegacyMessageException,
                      InvalidMessageException,
                      DuplicateMessageException,
                      NoSessionException

Decrypt a SenderKey group message.

Parameters:

senderKeyMessageBytes - The received ciphertext.

callback - A callback that is triggered after decryption is complete, but before the updated session state has been committed to the session DB. This allows some implementations to store the committed plaintext to a DB first, in case they are concerned with a crash happening between the time the session state is updated but before they're able to store the plaintext to disk.

Returns:

Plaintext

Throws:

LegacyMessageException

InvalidMessageException

DuplicateMessageException

NoSessionException