ch.epfl.dedis.calypso

Class WriteData

java.lang.Object

ch.epfl.dedis.calypso.WriteData

public class WriteData
extends Object

A WriteData is the data that is sent to the calypsoWrite contract store a write request with the encrypted document. Stored on BzyCoin, it will have the following fields:

- EncData - the encrypted data, should be smaller than 8MB - U, Ubar, E, F, Cs - the symmetric key used to encrypt the data, itself encrypted to the Long Term Secret key - ExtraData - plain text data that is stored as-is on the ledger - LTSID - the Long Term Secret ID used to encrypt the data

Constructor Summary

Constructors

Constructor and Description
WriteData(CreateLTSReply lts, byte[] dataEnc, byte[] keyMaterial, byte[] extraData, DarcId publisher) Create a new document by giving all possible parameters.

Method Summary

Modifier and Type	Method and Description
static WriteData	fromByzcoin(ByzCoinRPC bc, InstanceId id) Recreates a WriteData from an instanceid.
static WriteData	fromInstance(Instance inst) Recreates a WriteData from an instance.
static WriteData	fromProto(byte[] buf) Takes a byte array as an input to parse into the protobuf representation of WriteData.
byte[]	getDataEnc() Get the encrypted data.
byte[]	getExtraData() Get the extra data.
Calypso.Write	toProto()

Methods inherited from class java.lang.Object

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

Constructor Detail

WriteData

public WriteData(CreateLTSReply lts,
                 byte[] dataEnc,
                 byte[] keyMaterial,
                 byte[] extraData,
                 DarcId publisher)
          throws CothorityException

Create a new document by giving all possible parameters. This call supposes that the data sent here is already encrypted using the keyMaterial and can be decrypted using keyMaterial.

Parameters:

lts - Long Term Secret parameters

dataEnc - The ciphertext which will be stored _as is_ on ByzCoin. There is a limit on the size of the ciphertext which depends on the block size of ByzCoin. Typically the limit is slightly below the block size because the block also contains other metadata. You can find the block size using ChainConfigInstance.

keyMaterial - The symmetric key plus eventually an IV. This will be encrypted under the shared symmetricKey of the cothority.

extraData - data that will _not be encrypted_ but will be visible in cleartext on ByzCoin.

publisher - The darc with a rule for calypsoWrite and calypsoRead.

Throws:

CothorityException - if something went wrong

Method Detail

fromByzcoin

public static WriteData fromByzcoin(ByzCoinRPC bc,
                                    InstanceId id)
                             throws CothorityNotFoundException,
                                    CothorityCommunicationException,
                                    CothorityCryptoException

Recreates a WriteData from an instanceid.

Parameters:

bc - a running Byzcoin service

id - an instanceId of a WriteInstance

Returns:

the new WriteData

Throws:

CothorityNotFoundException - if the requested instance cannot be found

CothorityCommunicationException - if something went wrong with the communication

CothorityCryptoException - if there is something wrong with the proof

fromInstance

public static WriteData fromInstance(Instance inst)
                              throws CothorityNotFoundException

Recreates a WriteData from an instance.

Parameters:

inst - an instance representing a WriteData

Returns:

WriteData

Throws:

CothorityNotFoundException - if the requested instance cannot be found

getDataEnc

public byte[] getDataEnc()

Get the encrypted data.

Returns:

the encrypted data

getExtraData

public byte[] getExtraData()

Get the extra data.

Returns:

the extra data

toProto

public Calypso.Write toProto()

fromProto

public static WriteData fromProto(byte[] buf)
                           throws com.google.protobuf.InvalidProtocolBufferException

Takes a byte array as an input to parse into the protobuf representation of WriteData.

Parameters:

buf - the protobuf data

Returns:

WriteData

Throws:

com.google.protobuf.InvalidProtocolBufferException - if the protobuf data is invalid.