ch.epfl.dedis.ocs

Class WriteRequest

java.lang.Object

ch.epfl.dedis.ocs.WriteRequest

public class WriteRequest
extends Object

dedis/lib WriteRequest.java Purpose: Wrapping all fields necessary for a document.

Field Summary

Fields

Modifier and Type	Field and Description
byte[]	dataEnc
byte[]	extraData
WriteRequestId	id
byte[]	keyMaterial
Darc	owner

Constructor Summary

Constructors

Constructor and Description
WriteRequest(byte[] dataEnc, byte[] keyMaterial, Darc owner, byte[] extraData) Create a new document by giving all possible parameters.
WriteRequest(byte[] data, int keylen, Darc owner) Creates a new document from data, creates a new Darc, a symmetric symmetricKey and encrypts the data using CBC-RSA.
WriteRequest(String data, int keylen, Darc owner) Overloaded constructor for WriteRequest, but taking a string rather than an array of bytes.
WriteRequest(WriteRequest wr) Creates a new document - copies from an existing.

Method Summary

Modifier and Type	Method and Description
DarcSignature	getSignature(OnchainSecretsRPC ocs, Signer publisher) Creates a correct signature-path starting from the admin darc and signs that path to get a correct write-request.
OCSProto.Write	toProto(Point X, SkipblockId scid) Returns a protobuf-formatted block that can be sent to the cothority for storage on the skipchain.

Methods inherited from class java.lang.Object

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

Field Detail

dataEnc

public byte[] dataEnc

keyMaterial

public byte[] keyMaterial

owner

public Darc owner

extraData

public byte[] extraData

id

public WriteRequestId id

Constructor Detail

WriteRequest

public WriteRequest(WriteRequest wr)

Creates a new document - copies from an existing.

Parameters:

wr - - an existing document.

WriteRequest

public WriteRequest(byte[] data,
                    int keylen,
                    Darc owner)
             throws CothorityCryptoException

Creates a new document from data, creates a new Darc, a symmetric symmetricKey and encrypts the data using CBC-RSA.

Parameters:

data - - any data that will be stored encrypted on the skipchain. There is a 10MB-limit on how much data can be stored. If you need more, this must be a pointer to an off-chain storage.

keylen - - how long the symmetric symmetricKey should be, in bytes. 16 bytes should be a safe guess for the moment.

Throws:

CothorityCryptoException - in the case the encryption doesn't work

WriteRequest

public WriteRequest(String data,
                    int keylen,
                    Darc owner)
             throws CothorityCryptoException

Overloaded constructor for WriteRequest, but taking a string rather than an array of bytes.

Parameters:

data - - data for the document, will be encrypted

keylen - - keylength - 16 is a good start.

Throws:

CothorityCryptoException

WriteRequest

public WriteRequest(byte[] dataEnc,
                    byte[] keyMaterial,
                    Darc owner,
                    byte[] extraData)

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:

dataEnc - the already encrypted data

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

owner - the owner is allowed to give access to the document

extraData - data that will _not be encrypted_ but will be visible in cleartext on the skipchain

Method Detail

toProto

public OCSProto.Write toProto(Point X,
                              SkipblockId scid)
                       throws CothorityCommunicationException

Returns a protobuf-formatted block that can be sent to the cothority for storage on the skipchain. The data and the keyMaterial will be encrypted and stored encrypted on the skipchain. The id, extraData and darc however will be stored in clear.

Parameters:

X - - the public symmetricKey of the ocs-shard

scid - - the id of the skipchain

Returns:

- OCSWrite to be sent to the cothority

Throws:

CothorityCommunicationException

getSignature

public DarcSignature getSignature(OnchainSecretsRPC ocs,
                                  Signer publisher)
                           throws CothorityCryptoException,
                                  CothorityCommunicationException

Creates a correct signature-path starting from the admin darc and signs that path to get a correct write-request.

Parameters:

ocs - OnchainSecretsRPC class to request the path

publisher - allowed to sign for write requests

Returns:

a valid signature for a write request

Throws:

CothorityCryptoException

CothorityCommunicationException