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Bouncy Castle Cryptography Library 1.77.0
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org.bouncycastle.crypto.agreement.jpake
Class JPAKEUtil

java.lang.Object
  |
  +--org.bouncycastle.crypto.agreement.jpake.JPAKEUtil
public class JPAKEUtil
extends java.lang.Object

Primitives needed for a J-PAKE exchange.

The recommended way to perform a J-PAKE exchange is by using two JPAKEParticipants. Internally, those participants call these primitive operations in JPAKEUtil.

The primitives, however, can be used without a JPAKEParticipant if needed.

Constructor Summary
JPAKEUtil()
           
 
Method Summary
static java.math.BigInteger calculateA(java.math.BigInteger p, java.math.BigInteger q, java.math.BigInteger gA, java.math.BigInteger x2s)
          Calculate A as done in round 2.
static java.math.BigInteger calculateGA(java.math.BigInteger p, java.math.BigInteger gx1, java.math.BigInteger gx3, java.math.BigInteger gx4)
          Calculate ga as done in round 2.
static java.math.BigInteger calculateGx(java.math.BigInteger p, java.math.BigInteger g, java.math.BigInteger x)
          Calculate g^x mod p as done in round 1.
static java.math.BigInteger calculateKeyingMaterial(java.math.BigInteger p, java.math.BigInteger q, java.math.BigInteger gx4, java.math.BigInteger x2, java.math.BigInteger s, java.math.BigInteger B)
          Calculates the keying material, which can be done after round 2 has completed.
static java.math.BigInteger calculateMacTag(java.lang.String participantId, java.lang.String partnerParticipantId, java.math.BigInteger gx1, java.math.BigInteger gx2, java.math.BigInteger gx3, java.math.BigInteger gx4, java.math.BigInteger keyingMaterial, Digest digest)
          Calculates the MacTag (to be used for key confirmation), as defined by NIST SP 800-56A Revision 1, Section 8.2 Unilateral Key Confirmation for Key Agreement Schemes.
static java.math.BigInteger calculateS(java.math.BigInteger q, byte[] password)
          Converts the given password to a BigInteger mod q.
static java.math.BigInteger calculateS(java.math.BigInteger q, char[] password)
          Converts the given password to a BigInteger mod q.
static java.math.BigInteger calculateS(char[] password)
          Deprecated. Use version including the modulus instead.
static java.math.BigInteger calculateX2s(java.math.BigInteger q, java.math.BigInteger x2, java.math.BigInteger s)
          Calculate x2 * s as done in round 2.
static java.math.BigInteger[] calculateZeroKnowledgeProof(java.math.BigInteger p, java.math.BigInteger q, java.math.BigInteger g, java.math.BigInteger gx, java.math.BigInteger x, java.lang.String participantId, Digest digest, java.security.SecureRandom random)
          Calculate a zero knowledge proof of x using Schnorr's signature.
static java.math.BigInteger generateX1(java.math.BigInteger q, java.security.SecureRandom random)
          Return a value that can be used as x1 or x3 during round 1.
static java.math.BigInteger generateX2(java.math.BigInteger q, java.security.SecureRandom random)
          Return a value that can be used as x2 or x4 during round 1.
static void validateGa(java.math.BigInteger ga)
          Validates that ga is not 1.
static void validateGx4(java.math.BigInteger gx4)
          Validates that g^x4 is not 1.
static void validateMacTag(java.lang.String participantId, java.lang.String partnerParticipantId, java.math.BigInteger gx1, java.math.BigInteger gx2, java.math.BigInteger gx3, java.math.BigInteger gx4, java.math.BigInteger keyingMaterial, Digest digest, java.math.BigInteger partnerMacTag)
          Validates the MacTag received from the partner participant.
static void validateNotNull(java.lang.Object object, java.lang.String description)
          Validates that the given object is not null.
static void validateParticipantIdsDiffer(java.lang.String participantId1, java.lang.String participantId2)
          Validates that the given participant ids are not equal.
static void validateParticipantIdsEqual(java.lang.String expectedParticipantId, java.lang.String actualParticipantId)
          Validates that the given participant ids are equal.
static void validateZeroKnowledgeProof(java.math.BigInteger p, java.math.BigInteger q, java.math.BigInteger g, java.math.BigInteger gx, java.math.BigInteger[] zeroKnowledgeProof, java.lang.String participantId, Digest digest)
          Validates the zero knowledge proof (generated by calculateZeroKnowledgeProof(BigInteger, BigInteger, BigInteger, BigInteger, BigInteger, String, Digest, SecureRandom)) is correct.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

JPAKEUtil

public JPAKEUtil()
Method Detail

generateX1

public static java.math.BigInteger generateX1(java.math.BigInteger q,
                                              java.security.SecureRandom random)
Return a value that can be used as x1 or x3 during round 1.

The returned value is a random value in the range [0, q-1].

generateX2

public static java.math.BigInteger generateX2(java.math.BigInteger q,
                                              java.security.SecureRandom random)
Return a value that can be used as x2 or x4 during round 1.

The returned value is a random value in the range [1, q-1].

calculateS

public static java.math.BigInteger calculateS(char[] password)
Deprecated. Use version including the modulus instead.

Converts the given password to a BigInteger for use in arithmetic calculations.

calculateS

public static java.math.BigInteger calculateS(java.math.BigInteger q,
                                              byte[] password)
                                       throws CryptoException
Converts the given password to a BigInteger mod q.

calculateS

public static java.math.BigInteger calculateS(java.math.BigInteger q,
                                              char[] password)
                                       throws CryptoException
Converts the given password to a BigInteger mod q.

calculateGx

public static java.math.BigInteger calculateGx(java.math.BigInteger p,
                                               java.math.BigInteger g,
                                               java.math.BigInteger x)
Calculate g^x mod p as done in round 1.

calculateGA

public static java.math.BigInteger calculateGA(java.math.BigInteger p,
                                               java.math.BigInteger gx1,
                                               java.math.BigInteger gx3,
                                               java.math.BigInteger gx4)
Calculate ga as done in round 2.

calculateX2s

public static java.math.BigInteger calculateX2s(java.math.BigInteger q,
                                                java.math.BigInteger x2,
                                                java.math.BigInteger s)
Calculate x2 * s as done in round 2.

calculateA

public static java.math.BigInteger calculateA(java.math.BigInteger p,
                                              java.math.BigInteger q,
                                              java.math.BigInteger gA,
                                              java.math.BigInteger x2s)
Calculate A as done in round 2.

calculateZeroKnowledgeProof

public static java.math.BigInteger[] calculateZeroKnowledgeProof(java.math.BigInteger p,
                                                                 java.math.BigInteger q,
                                                                 java.math.BigInteger g,
                                                                 java.math.BigInteger gx,
                                                                 java.math.BigInteger x,
                                                                 java.lang.String participantId,
                                                                 Digest digest,
                                                                 java.security.SecureRandom random)
Calculate a zero knowledge proof of x using Schnorr's signature. The returned array has two elements {g^v, r = v-x*h} for x.

validateGx4

public static void validateGx4(java.math.BigInteger gx4)
                        throws CryptoException
Validates that g^x4 is not 1.
Throws:
CryptoException - if g^x4 is 1

validateGa

public static void validateGa(java.math.BigInteger ga)
                       throws CryptoException
Validates that ga is not 1.

As described by Feng Hao[]

Alice could simply check ga != 1 to ensure it is a generator. In fact, as we will explain in Section 3, (x1 + x3 + x4 ) is random over Zq even in the face of active attacks. Hence, the probability for ga = 1 is extremely small - on the order of 2^160 for 160-bit q.

Throws:
CryptoException - if ga is 1

validateZeroKnowledgeProof

public static void validateZeroKnowledgeProof(java.math.BigInteger p,
                                              java.math.BigInteger q,
                                              java.math.BigInteger g,
                                              java.math.BigInteger gx,
                                              java.math.BigInteger[] zeroKnowledgeProof,
                                              java.lang.String participantId,
                                              Digest digest)
                                       throws CryptoException
Validates the zero knowledge proof (generated by calculateZeroKnowledgeProof(BigInteger, BigInteger, BigInteger, BigInteger, BigInteger, String, Digest, SecureRandom)) is correct.
Throws:
CryptoException - if the zero knowledge proof is not correct

calculateKeyingMaterial

public static java.math.BigInteger calculateKeyingMaterial(java.math.BigInteger p,
                                                           java.math.BigInteger q,
                                                           java.math.BigInteger gx4,
                                                           java.math.BigInteger x2,
                                                           java.math.BigInteger s,
                                                           java.math.BigInteger B)
Calculates the keying material, which can be done after round 2 has completed. A session key must be derived from this key material using a secure key derivation function (KDF). The KDF used to derive the key is handled externally (i.e. not by JPAKEParticipant). KeyingMaterial = (B/g^{x2*x4*s})^x2

validateParticipantIdsDiffer

public static void validateParticipantIdsDiffer(java.lang.String participantId1,
                                                java.lang.String participantId2)
                                         throws CryptoException
Validates that the given participant ids are not equal. (For the J-PAKE exchange, each participant must use a unique id.)
Throws:
CryptoException - if the participantId strings are equal.

validateParticipantIdsEqual

public static void validateParticipantIdsEqual(java.lang.String expectedParticipantId,
                                               java.lang.String actualParticipantId)
                                        throws CryptoException
Validates that the given participant ids are equal. This is used to ensure that the payloads received from each round all come from the same participant.
Throws:
CryptoException - if the participantId strings are equal.

validateNotNull

public static void validateNotNull(java.lang.Object object,
                                   java.lang.String description)
Validates that the given object is not null.
Parameters:
object - object in question
description - name of the object (to be used in exception message)
Throws:
NullPointerException - if the object is null.

calculateMacTag

public static java.math.BigInteger calculateMacTag(java.lang.String participantId,
                                                   java.lang.String partnerParticipantId,
                                                   java.math.BigInteger gx1,
                                                   java.math.BigInteger gx2,
                                                   java.math.BigInteger gx3,
                                                   java.math.BigInteger gx4,
                                                   java.math.BigInteger keyingMaterial,
                                                   Digest digest)
Calculates the MacTag (to be used for key confirmation), as defined by NIST SP 800-56A Revision 1, Section 8.2 Unilateral Key Confirmation for Key Agreement Schemes. MacTag = HMAC(MacKey, MacLen, MacData) MacKey = H(K || "JPAKE_KC") MacData = "KC_1_U" || participantId || partnerParticipantId || gx1 || gx2 || gx3 || gx4 Note that both participants use "KC_1_U" because the sender of the round 3 message is always the initiator for key confirmation. HMAC = HMac used with the given Digest H = The given Digest MacLen = length of MacTag

validateMacTag

public static void validateMacTag(java.lang.String participantId,
                                  java.lang.String partnerParticipantId,
                                  java.math.BigInteger gx1,
                                  java.math.BigInteger gx2,
                                  java.math.BigInteger gx3,
                                  java.math.BigInteger gx4,
                                  java.math.BigInteger keyingMaterial,
                                  Digest digest,
                                  java.math.BigInteger partnerMacTag)
                           throws CryptoException
Validates the MacTag received from the partner participant.
Parameters:
partnerMacTag - the MacTag received from the partner.
Throws:
CryptoException - if the participantId strings are equal.
Overview  Package   Class  Tree  Deprecated  Index  Help 
Bouncy Castle Cryptography Library 1.77.0
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SUMMARY:  INNER | FIELD | CONSTR | METHOD DETAIL:  FIELD | CONSTR | METHOD