org.mozilla.jss.crypto

Class PQGParams


public class PQGParams
extends DSAParameterSpec

PQG parameters for DSA key generation, along with the seed, counter, and H values for verification.

This class has two main purposes: generating PQG parameters and verifying PQG parameters. To generate PQG parameters, call one of the static generate methods. They will return a new set of PQG paramters. To verify existing PQG parameters, create a new PQGParams object with the constructor and call paramsAreValid on the object.

It is necessary to call CryptoManager.initialize before using this class.

Constructor Summary

PQGParams(BigInteger P, BigInteger Q, BigInteger G, BigInteger seed, int counter, BigInteger H)
Creates a PQGParams object from a set of pre-computed DSA parameters.

Method Summary

static byte[]
BigIntegerToUnsignedByteArray(BigInteger big)
Produces an unsigned byte-array representation of a BigInteger.
static PQGParams
generate(int keySize)
Generates P, Q, and G parameters for DSA key generation.
static PQGParams
generate(int keySize, int seedBytes)
Generates P, Q, and G parameters for DSA key generation.
int
getCounter()
BigInteger
getH()
BigInteger
getSeed()
boolean
paramsAreValid()
Verifies the PQG parameters using the seed, counter, and H values.

Constructor Details

PQGParams

public PQGParams(BigInteger P,
                 BigInteger Q,
                 BigInteger G,
                 BigInteger seed,
                 int counter,
                 BigInteger H)
Creates a PQGParams object from a set of pre-computed DSA parameters.
Parameters:
P - The DSA prime parameter.
Q - The DSA sub-prime parameter.
G - The DSA base parameter.
seed - The Seed used to calculate P, Q, and G.
counter - The Counter (C) used to calculate P, Q, and G.
H - The H value used to generate P, Q, and G.

Method Details

BigIntegerToUnsignedByteArray

public static byte[] BigIntegerToUnsignedByteArray(BigInteger big)
Produces an unsigned byte-array representation of a BigInteger.

BigInteger adds an extra sign bit to the beginning of its byte array representation. In some cases this will cause the size of the byte array to increase, which may be unacceptable for some applications. This function returns a minimal byte array representing the BigInteger without extra sign bits.

Returns:
An unsigned, big-endian byte array representation of a BigInteger.

generate

public static PQGParams generate(int keySize)
            throws java.security.InvalidParameterException,
                   PQGParamGenException
Generates P, Q, and G parameters for DSA key generation. Also provides the seed, counter, and H values for verification of the P, Q, and G. The parameters are generated and then verified before being returned. The length of the Seed will equal the length of P. It is necessary to call one of the CryptoManager.initialize functions before calling this method.
Parameters:
keySize - The size of P in bits. Keys generated by these P, Q, and G values will have this length. Valid key sizes are multiples of 64 in the closed interval [512,1024]. This also dictates the length of H and Seed.
Returns:
A new set of P, Q, and G parameters, along with the Seed, Counter, and H values used to generate them.
Throws:
PQGParamGenException - If an error occurs during the generation process.
See Also:
org.mozilla.jss.CryptoManager.initialize

generate

public static PQGParams generate(int keySize,
                                 int seedBytes)
            throws java.security.InvalidParameterException,
                   PQGParamGenException
Generates P, Q, and G parameters for DSA key generation. Also provides the seed, counter, and H values for verification of the P, Q, and G. The parameters are generated and then verified before being returned. It is necessary to call one of the CryptoManager.initialize functions before calling this method.
Parameters:
keySize - The size of P in bits. Keys generated by these P, Q, and G values will have this length. Valid key sizes are multiples of 64 in the closed interval [512,1024]. This also dictates the length of H.
seedBytes - The number of bytes in the Seed value used to generate P, Q, and G. seedBytes must be from the closed interval [20,255].
Returns:
A new set of P, Q, and G parameters, along with the Seed, Counter, and H values used to generate them.
Throws:
PQGParamGenException - If an error occurs during the generation process.
See Also:
org.mozilla.jss.CryptoManager.initialize

getCounter

public int getCounter()
Returns:
The Counter (C) used to generate P, Q, and G.

getH

public BigInteger getH()
Returns:
The H value used to generate P, Q, and G.

getSeed

public BigInteger getSeed()
Returns:
The Seed used to generate P, Q, and G.

paramsAreValid

public boolean paramsAreValid()
Verifies the PQG parameters using the seed, counter, and H values.
Returns:
true if the parameters verified correctly, false if they did not verify.