ch.epfl.dedis.lib.darc

Class Darc

java.lang.Object

ch.epfl.dedis.lib.darc.Darc

public class Darc
extends Object

Darc stands for distributed access right control. It provides a powerful access control policy that supports logical expressions, delegation of rights, offline verification and so on. Please refer to https://github.com/dedis/cothority/byzcoin/README.md#darc for more information.

Field Summary

Fields

Modifier and Type	Field and Description
static String	RuleEvolve
static String	RuleSignature

Constructor Summary

Constructors

Constructor and Description
Darc(byte[] buf) Convenience constructure
Darc(DarcProto.Darc proto) Convenience constructor
Darc(List<Identity> owners, List<Identity> signers, byte[] desc) Convenience constructor
Darc(Rules rules, byte[] desc) The Darc constructor.

Method Summary

Modifier and Type	Method and Description
void	addIdentity(String action, Identity id, String link)
Darc	copyEvolve()
Darc	copyRulesAndVersion()
boolean	equals(Object other) Compares this darc with another darc.
List<String>	getActions()
DarcId	getBaseId() Gets the base-ID of the darc, i.e.
byte[]	getExpression(String action) Returns a copy of the expression stored in the rule.
DarcId	getId() Calculate the getId of the darc by calculating the sha-256 of the invariant parts which excludes the delegation-signature.
Identity	getIdentity()
DarcId	getPrevID()
long	getVersion()
void	increaseVersion() Updates the version of the darc and clears any eventual signatures from previous evolutions.
static Rules	initRules(List<Identity> owners, List<Identity> signers) This is a convenience function that initialise a set of rules with the default actions "_evolve" and "_sign".
byte[]	removeAction(String action) Removes the given action.
void	setBaseId(DarcId id)
void	setPrevId(Darc d)
void	setPrevId(DarcId id)
void	setRule(String action, byte[] expression) Sets a rule to be the action/expression pair.
DarcProto.Darc	toProto() Creates the protobuf representation of the darc.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

RuleSignature

public static final String RuleSignature

See Also:

Constant Field Values

RuleEvolve

public static final String RuleEvolve

See Also:

Constant Field Values

Constructor Detail

Darc

public Darc(Rules rules,
            byte[] desc)

The Darc constructor.

Parameters:

rules - The initial set of rules, consider using initRules to create them.

desc - The description.

Darc

public Darc(List<Identity> owners,
            List<Identity> signers,
            byte[] desc)

Convenience constructor

Parameters:

owners - a list of owners that are allowed to evolve the darc

signers - a list of signers on behalf of that darc

desc - free form description of the darc

Darc

public Darc(DarcProto.Darc proto)
     throws CothorityCryptoException

Convenience constructor

Parameters:

proto - proto representation of the darc

Throws:

CothorityCryptoException - if there's a problem with the cryptography

Darc

public Darc(byte[] buf)
     throws com.google.protobuf.InvalidProtocolBufferException,
            CothorityCryptoException

Convenience constructure

Parameters:

buf - byte representation of protobuf representation

Throws:

com.google.protobuf.InvalidProtocolBufferException - if the Darc cannot be parsed

CothorityCryptoException - if there's a problem with the cryptography

Method Detail

setRule

public void setRule(String action,
                    byte[] expression)

Sets a rule to be the action/expression pair. This will overwrite an existing rule or create a new one.

Parameters:

action - the action

expression - the expression

addIdentity

public void addIdentity(String action,
                        Identity id,
                        String link)
                 throws CothorityCryptoException

Throws:

CothorityCryptoException

getExpression

public byte[] getExpression(String action)

Returns a copy of the expression stored in the rule. If the expression has not been found, it returns null.

Parameters:

action - - which expression to return

Returns:

the expression corresponding to the action, or null if not found.

getActions

public List<String> getActions()

Returns:

A list of all actions stored in this darc.

removeAction

public byte[] removeAction(String action)

Removes the given action.

Parameters:

action - if that action is in the set of rules, removes it.

Returns:

the expression of the action, or null if it didn't exist

increaseVersion

public void increaseVersion()

Updates the version of the darc and clears any eventual signatures from previous evolutions.

toProto

public DarcProto.Darc toProto()

Creates the protobuf representation of the darc.

Returns:

The protobuf representation.

getId

public DarcId getId()

Calculate the getId of the darc by calculating the sha-256 of the invariant parts which excludes the delegation-signature.

Returns:

sha256

setPrevId

public void setPrevId(DarcId id)

Parameters:

id - the id of the previous darc.

setBaseId

public void setBaseId(DarcId id)

Parameters:

id - the base-id to set

setPrevId

public void setPrevId(Darc d)
               throws CothorityCryptoException

Parameters:

d - the previous darc

Throws:

CothorityCryptoException - if there's a problem with the cryptography

getBaseId

public DarcId getBaseId()
                 throws CothorityCryptoException

Gets the base-ID of the darc, i.e. the ID before any evolution.

Returns:

base-ID

Throws:

CothorityCryptoException - if there's a problem with the cryptography

getPrevID

public DarcId getPrevID()

getVersion

public long getVersion()

Returns:

the current version.

copyRulesAndVersion

public Darc copyRulesAndVersion()

Returns:

a copy of the darc with the same version number, rules and description. The prevID and baseID are initiated to null, which must be set afterwards if the darc is to be used.

Throws:

CothorityCryptoException - if there's a problem with the cryptography

copyEvolve

public Darc copyEvolve()
                throws CothorityCryptoException

Returns:

a copy of the darc with the next version number and prevId and baseId set up.

Throws:

CothorityCryptoException - if there's a problem with the cryptography

getIdentity

public Identity getIdentity()
                     throws CothorityCryptoException

Returns:

the corresponding identityDarc

Throws:

CothorityCryptoException - if there's a problem with the cryptography

toString

public String toString()

Overrides:

toString in class Object

initRules

public static Rules initRules(List<Identity> owners,
                              List<Identity> signers)

This is a convenience function that initialise a set of rules with the default actions "_evolve" and "_sign". Signers are joined with logical-Or, owners are joined with logical-AND. If other expressions are needed, please set the rules manually.

Parameters:

owners - A list of owners.

signers - A list of signers.

Returns:

The action-expression mapping, also known as the rule.

equals

public boolean equals(Object other)

Compares this darc with another darc. It returns only true if it is the same version and the same baseId.

Overrides:

equals in class Object

Parameters:

other - another Darc

Returns:

true if both are equal with regard to the baseId and the version.