org.bouncycastle.crypto.agreement.srp

Class SRP6Server

java.lang.Object

org.bouncycastle.crypto.agreement.srp.SRP6Server

public class SRP6Server
extends Object

Implements the server side SRP-6a protocol. Note that this class is stateful, and therefore NOT threadsafe. This implementation of SRP is based on the optimized message sequence put forth by Thomas Wu in the paper "SRP-6: Improvements and Refinements to the Secure Remote Password Protocol, 2002"

Field Summary

Fields

Modifier and Type	Field and Description
protected BigInteger	A
protected BigInteger	b
protected BigInteger	B
protected Digest	digest
protected BigInteger	g
protected BigInteger	Key
protected BigInteger	M1
protected BigInteger	M2
protected BigInteger	N
protected SecureRandom	random
protected BigInteger	S
protected BigInteger	u
protected BigInteger	v

Constructor Summary

Constructors

Constructor and Description
SRP6Server()

Method Summary

Modifier and Type	Method and Description
BigInteger	calculateSecret(BigInteger clientA) Processes the client's credentials.
BigInteger	calculateServerEvidenceMessage() Computes the server evidence message M2 using the previously verified values.
BigInteger	calculateSessionKey() Computes the final session key as a result of the SRP successful mutual authentication To be called after calculating the server evidence message M2.
BigInteger	generateServerCredentials() Generates the server's credentials that are to be sent to the client.
void	init(BigInteger N, BigInteger g, BigInteger v, Digest digest, SecureRandom random) Initialises the server to accept a new client authentication attempt
void	init(SRP6GroupParameters group, BigInteger v, Digest digest, SecureRandom random)
protected BigInteger	selectPrivateValue()
boolean	verifyClientEvidenceMessage(BigInteger clientM1) Authenticates the received client evidence message M1 and saves it only if correct.

Methods inherited from class java.lang.Object

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

Field Detail

N

protected BigInteger N

g

protected BigInteger g

v

protected BigInteger v

random

protected SecureRandom random

digest

protected Digest digest

A

protected BigInteger A

b

protected BigInteger b

B

protected BigInteger B

u

protected BigInteger u

S

protected BigInteger S

M1

protected BigInteger M1

M2

protected BigInteger M2

Key

protected BigInteger Key

Constructor Detail

SRP6Server

public SRP6Server()

Method Detail

init

public void init(BigInteger N,
                 BigInteger g,
                 BigInteger v,
                 Digest digest,
                 SecureRandom random)

Initialises the server to accept a new client authentication attempt

Parameters:

N - The safe prime associated with the client's verifier

g - The group parameter associated with the client's verifier

v - The client's verifier

digest - The digest algorithm associated with the client's verifier

random - For key generation

init

public void init(SRP6GroupParameters group,
                 BigInteger v,
                 Digest digest,
                 SecureRandom random)

generateServerCredentials

public BigInteger generateServerCredentials()

Generates the server's credentials that are to be sent to the client.

Returns:

The server's public value to the client

calculateSecret

public BigInteger calculateSecret(BigInteger clientA)
                           throws CryptoException

Processes the client's credentials. If valid the shared secret is generated and returned.

Parameters:

clientA - The client's credentials

Returns:

A shared secret BigInteger

Throws:

CryptoException - If client's credentials are invalid

selectPrivateValue

protected BigInteger selectPrivateValue()

verifyClientEvidenceMessage

public boolean verifyClientEvidenceMessage(BigInteger clientM1)
                                    throws CryptoException

Authenticates the received client evidence message M1 and saves it only if correct. To be called after calculating the secret S.

Parameters:

clientM1 - the client side generated evidence message

Returns:

A boolean indicating if the client message M1 was the expected one.

Throws:

CryptoException

calculateServerEvidenceMessage

public BigInteger calculateServerEvidenceMessage()
                                          throws CryptoException

Computes the server evidence message M2 using the previously verified values. To be called after successfully verifying the client evidence message M1.

Returns:

M2: the server side generated evidence message

Throws:

CryptoException

calculateSessionKey

public BigInteger calculateSessionKey()
                               throws CryptoException

Computes the final session key as a result of the SRP successful mutual authentication To be called after calculating the server evidence message M2.

Returns:

Key: the mutual authenticated symmetric session key

Throws:

CryptoException