SRP6Client (Bouncy Castle Library 1.60 API Specification)

java.lang.Object
- org.bouncycastle.crypto.agreement.srp.SRP6Client

```
public class SRP6Client
extends java.lang.Object
```
Implements the client 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	Description
`protected java.math.BigInteger`	`a`
`protected java.math.BigInteger`	`A`
`protected java.math.BigInteger`	`B`
`protected Digest`	`digest`
`protected java.math.BigInteger`	`g`
`protected java.math.BigInteger`	`Key`
`protected java.math.BigInteger`	`M1`
`protected java.math.BigInteger`	`M2`
`protected java.math.BigInteger`	`N`
`protected java.security.SecureRandom`	`random`
`protected java.math.BigInteger`	`S`
`protected java.math.BigInteger`	`u`
`protected java.math.BigInteger`	`x`

Constructor Summary

Constructors
Constructor Description

SRP6Client()

Constructors
Constructor	Description
`SRP6Client()`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`java.math.BigInteger`	`calculateClientEvidenceMessage()`	Computes the client evidence message M1 using the previously received values.
`java.math.BigInteger`	`calculateSecret(java.math.BigInteger serverB)`	Generates the secret S given the server's credentials
`java.math.BigInteger`	`calculateSessionKey()`	Computes the final session key as a result of the SRP successful mutual authentication To be called after verifying the server evidence message M2.
`java.math.BigInteger`	`generateClientCredentials(byte[] salt, byte[] identity, byte[] password)`	Generates client's credentials given the client's salt, identity and password
`void`	`init(java.math.BigInteger N, java.math.BigInteger g, Digest digest, java.security.SecureRandom random)`	Initialises the client to begin new authentication attempt
`void`	`init(SRP6GroupParameters group, Digest digest, java.security.SecureRandom random)`
`protected java.math.BigInteger`	`selectPrivateValue()`
`boolean`	`verifyServerEvidenceMessage(java.math.BigInteger serverM2)`	Authenticates the server evidence message M2 received 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 java.math.BigInteger N
```
  - g
```
protected java.math.BigInteger g
```
  - a
```
protected java.math.BigInteger a
```
  - A
```
protected java.math.BigInteger A
```
  - B
```
protected java.math.BigInteger B
```
  - x
```
protected java.math.BigInteger x
```
  - u
```
protected java.math.BigInteger u
```
  - S
```
protected java.math.BigInteger S
```
  - M1
```
protected java.math.BigInteger M1
```
  - M2
```
protected java.math.BigInteger M2
```
  - Key
```
protected java.math.BigInteger Key
```
  - digest
```
protected Digest digest
```
  - random
```
protected java.security.SecureRandom random
```
- Constructor Detail
  - SRP6Client
```
public SRP6Client()
```
- Method Detail
  - init
```
public void init(java.math.BigInteger N,
                 java.math.BigInteger g,
                 Digest digest,
                 java.security.SecureRandom random)
```
    Initialises the client to begin new authentication attempt
    
    Parameters:
    
    N - The safe prime associated with the client's verifier
    
    g - The group parameter associated with the client's verifier
    
    digest - The digest algorithm associated with the client's verifier
    
    random - For key generation
  - init
```
public void init(SRP6GroupParameters group,
                 Digest digest,
                 java.security.SecureRandom random)
```
  - generateClientCredentials
```
public java.math.BigInteger generateClientCredentials(byte[] salt,
                                                      byte[] identity,
                                                      byte[] password)
```
    Generates client's credentials given the client's salt, identity and password
    
    Parameters:
    
    salt - The salt used in the client's verifier.
    
    identity - The user's identity (eg. username)
    
    password - The user's password
    
    Returns:
    
    Client's public value to send to server
  - calculateSecret
```
public java.math.BigInteger calculateSecret(java.math.BigInteger serverB)
                                     throws CryptoException
```
    Generates the secret S given the server's credentials
    
    Parameters:
    
    serverB - The server's credentials
    
    Returns:
    
    Client's verification message for the server
    
    Throws:
    
    CryptoException - If server's credentials are invalid
  - selectPrivateValue
```
protected java.math.BigInteger selectPrivateValue()
```
  - calculateClientEvidenceMessage
```
public java.math.BigInteger calculateClientEvidenceMessage()
                                                    throws CryptoException
```
    Computes the client evidence message M1 using the previously received values. To be called after calculating the secret S.
    
    Returns:
    
    M1: the client side generated evidence message
    
    Throws:
    
    CryptoException
  - verifyServerEvidenceMessage
```
public boolean verifyServerEvidenceMessage(java.math.BigInteger serverM2)
                                    throws CryptoException
```
    Authenticates the server evidence message M2 received and saves it only if correct.
    
    Parameters:
    
    serverM2 - the server side generated evidence message
    
    Returns:
    
    A boolean indicating if the server message M2 was the expected one.
    
    Throws:
    
    CryptoException
  - calculateSessionKey
```
public java.math.BigInteger calculateSessionKey()
                                         throws CryptoException
```
    Computes the final session key as a result of the SRP successful mutual authentication To be called after verifying the server evidence message M2.
    
    Returns:
    
    Key: the mutually authenticated symmetric session key
    
    Throws:
    
    CryptoException

Class SRP6Client

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

N

g

a

A

B

x

u

S

M1

M2

Key

digest

random

Constructor Detail

SRP6Client

Method Detail

init

init

generateClientCredentials

calculateSecret

selectPrivateValue

calculateClientEvidenceMessage

verifyServerEvidenceMessage

calculateSessionKey