ch.epfl.dedis.byzcoin

Class Proof

java.lang.Object

ch.epfl.dedis.byzcoin.Proof

public class Proof
extends Object

Proof represents a key/value entry in the trie and the path to the root node.

Constructor Summary

Constructors

Constructor and Description
Proof(ByzCoinProto.Proof p, SkipblockId scID, InstanceId iid) Creates a new proof given a protobuf-representation and a trusted skipchain ID.

Method Summary

Modifier and Type	Method and Description
boolean	contractIsType(String expectedType) Checks whether the contract ID matches the expected ID.
boolean	exists(byte[] key) Check whether the key exists in the proof.
String	getContractID()
DarcId	getDarcBaseID()
Instance	getInstance() Creates an instance from the proof, it assumes the proof is valid.
byte[]	getKey()
SkipBlock	getLatest() Getter for the skipblock associated with this proof.
byte[]	getRoot() Getter for the Merkle-root, returns null if it doesn't exist.
byte[]	getValue()
StateChangeBody	getValues()
boolean	matches() Check whether the key (Instance ID) exists.
ByzCoinProto.Proof	toProto() Get the protobuf representation of the proof.

Methods inherited from class java.lang.Object

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

Constructor Detail

Proof

public Proof(ByzCoinProto.Proof p,
             SkipblockId scID,
             InstanceId iid)
      throws CothorityCryptoException

Creates a new proof given a protobuf-representation and a trusted skipchain ID.

Parameters:

p - is the protobuf representation

scID - is the skipchain ID

Throws:

CothorityCryptoException - if the verification of the forward links are wrong

Method Detail

getInstance

public Instance getInstance()

Creates an instance from the proof, it assumes the proof is valid.

Returns:

the instance stored in this proof.

toProto

public ByzCoinProto.Proof toProto()

Get the protobuf representation of the proof.

Returns:

the protobuf representation of the proof

getLatest

public SkipBlock getLatest()

Getter for the skipblock associated with this proof.

Returns:

SkipBlock

getRoot

public byte[] getRoot()

Getter for the Merkle-root, returns null if it doesn't exist.

getKey

public byte[] getKey()

Returns:

the key of the leaf node

getValues

public StateChangeBody getValues()

Returns:

the list of values in the leaf node. Return null if the value cannot be parsed.

getValue

public byte[] getValue()

Returns:

the value of the proof. Return null if the value cannot be parsed.

getContractID

public String getContractID()

Returns:

the string of the contractID. Return null if the value cannot be parsed.

getDarcBaseID

public DarcId getDarcBaseID()

Returns:

the Darc base ID defining the access rules to the instance.

contractIsType

public boolean contractIsType(String expectedType)

Checks whether the contract ID matches the expected ID.

Parameters:

expectedType - the expected contractId

Returns:

true if the proof is correct with regard to that Byzcoin id and the contract is of the expected type.

matches

public boolean matches()

Check whether the key (Instance ID) exists.

Returns:

true if the proof has the key/value pair stored on the leaf, false if it is a proof of absence or an error has occured.

exists

public boolean exists(byte[] key)
               throws CothorityCryptoException

Check whether the key exists in the proof.

Parameters:

key - is the value that we want to proof whether it exists or is absent.

Returns:

true if it's an existence proof.

Throws:

CothorityCryptoException - if an unexpected error occurs, an absence proof does not throw an exception.