org.cryptimeleon.craco.secretsharing.accessstructure

Class MonotoneSpanProgram

java.lang.Object

org.cryptimeleon.craco.secretsharing.accessstructure.AccessStructure

org.cryptimeleon.craco.secretsharing.accessstructure.MonotoneSpanProgram

All Implemented Interfaces:

LinearSecretSharing<PolicyFact>

public class MonotoneSpanProgram
extends AccessStructure

Access structure realized by using monotone span programs.

Field Summary

Fields inherited from class org.cryptimeleon.craco.secretsharing.accessstructure.AccessStructure

field, shareReceivers, thresholdTree

Constructor Summary

Constructors

Constructor and Description
MonotoneSpanProgram(Policy policy, org.cryptimeleon.math.structures.rings.zn.Zp field)

Method Summary

Modifier and Type	Method and Description
boolean	checkShareConsistency(org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement secret, java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement> shares) Outputs true if the given (full) set of shares is consistent with the given secret, meaning that all qualified subsets of the shares will recreate the given secret.
java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement>	completeShares(org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement secret, java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement> partialShares) Takes a partial set of shares and completes it to a full set of shares for the given secret.
java.util.HashMap<java.lang.Integer,PolicyFact>	getAttributes()
int	getNumberOfColumns() Calculates number of columns of the monotone span program matrix given by this instance.
java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement>	getShares(org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement secret) Calculates shares for the given secret.
java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement>	getSolvingVector(java.util.Set<? extends PolicyFact> setOfParties) Calculates set of solving secret shares for this monotone span program.
java.lang.String	toStringFor3DigitsGates() This method returns a string that contains a representation of the monotone span program given by this instance.

Methods inherited from class org.cryptimeleon.craco.secretsharing.accessstructure.AccessStructure

getSharedRing, getShareReceiverMap, isQualified, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.cryptimeleon.craco.secretsharing.LinearSecretSharing

getShareReceiver, getSharesOfReceiver, getSharesOfReceivers, isQualified, reconstruct

Constructor Detail

MonotoneSpanProgram

public MonotoneSpanProgram(Policy policy,
                           org.cryptimeleon.math.structures.rings.zn.Zp field)

Method Detail

getShares

public java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement> getShares(org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement secret)
                                                                                                  throws WrongAccessStructureException

Calculates shares for the given secret.

Parameters:

secret - the secret to calculate shares for

Returns:

a map mapping each share index to the corresponding share field element

Throws:

WrongAccessStructureException - if monotone span program matrix generation fails

getNumberOfColumns

public int getNumberOfColumns()
                       throws WrongAccessStructureException

Calculates number of columns of the monotone span program matrix given by this instance.

Returns:

number of columns of the monotone span program matrix

Throws:

WrongAccessStructureException - if monotone span program matrix generation fails

getSolvingVector

public java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement> getSolvingVector(java.util.Set<? extends PolicyFact> setOfParties)
                                                                                                         throws NoSatisfyingSet,
                                                                                                                WrongAccessStructureException

Calculates set of solving secret shares for this monotone span program.

Parameters:

setOfParties - the set of share-holding parties to consider

Returns:

a fulfilling map mapping each share index to the share field element

Throws:

NoSatisfyingSet - if the given set of parties cannot satisfy the monotone span program

WrongAccessStructureException - if the access structure is invalid

toStringFor3DigitsGates

public java.lang.String toStringFor3DigitsGates()
                                         throws WrongAccessStructureException

This method returns a string that contains a representation of the monotone span program given by this instance. The layout of the string is designed for access structures that contain only threshold nodes with at most 999 leaves.

Returns:

string representing the monotone span program

Throws:

WrongAccessStructureException - if monotone span program matrix generation fails

getAttributes

public java.util.HashMap<java.lang.Integer,PolicyFact> getAttributes()

completeShares

public java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement> completeShares(org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement secret,
                                                                                                              java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement> partialShares)
                                                                                                       throws java.lang.IllegalArgumentException

Description copied from interface: LinearSecretSharing

Takes a partial set of shares and completes it to a full set of shares for the given secret. In case of isQualified(S) == true this method will simply recreate the full set of shares.

The contract is that the two S in the following are distributed identically:

• \(S = \text{getShares}(s)\)
• \(S = \text{completeShares}(s, \{s_i' \; | \; i \in \text{getSharesOfReceivers(X)}\})\) with \(\{s_i'\} = \text{getShares}(s')\) and a subset \(X\) of share receivers.

(that property is called semi-smoothness)

Parameters:

secret - the desired secret for the completed shares

partialShares - the set of partial shares \(\{s_i \; | \; i \in \text{getSharesOfReceivers}(X)\}\)

Returns:

a complete set of shares distributed like getShares(secret) (if the given partial shares are distributed as in getShares())

Throws:

java.lang.IllegalArgumentException - if partialShares cannot be completed to secret

checkShareConsistency

public boolean checkShareConsistency(org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement secret,
                                     java.util.Map<java.lang.Integer,org.cryptimeleon.math.structures.rings.zn.Zp.ZpElement> shares)

Description copied from interface: LinearSecretSharing

Outputs true if the given (full) set of shares is consistent with the given secret, meaning that all qualified subsets of the shares will recreate the given secret.