gnu.crypto.key.dss
Class FIPS186

java.lang.Object
  |
  +--gnu.crypto.key.dss.FIPS186

public class FIPS186

extends java.lang.Object

An implementation of the DSA parameters generation as described in FIPS-186.

References:
Digital Signature Standard (DSS), Federal Information Processing Standards Publication 186. National Institute of Standards and Technology.

Field Summary

static int	DSA_PARAMS_COUNTER
static int	DSA_PARAMS_E
static int	DSA_PARAMS_G
static int	DSA_PARAMS_P
static int	DSA_PARAMS_Q
static int	DSA_PARAMS_SEED

Constructor Summary

FIPS186(int L, java.security.SecureRandom rnd)

Method Summary

java.math.BigInteger[]

generateParameters() This method generates the DSS p, q, and g parameters only when L (the modulus length) is not one of the following: 512, 768 and 1024.

Methods inherited from class java.lang.Object

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

Field Detail

DSA_PARAMS_SEED

public static final int DSA_PARAMS_SEED

See Also:

Constant Field Values

DSA_PARAMS_COUNTER

public static final int DSA_PARAMS_COUNTER

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Constant Field Values

DSA_PARAMS_Q

public static final int DSA_PARAMS_Q

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Constant Field Values

DSA_PARAMS_P

public static final int DSA_PARAMS_P

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Constant Field Values

DSA_PARAMS_E

public static final int DSA_PARAMS_E

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Constant Field Values

DSA_PARAMS_G

public static final int DSA_PARAMS_G

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Constant Field Values

Constructor Detail

FIPS186

public FIPS186(int L,
               java.security.SecureRandom rnd)

Method Detail

generateParameters

public java.math.BigInteger[] generateParameters()

This method generates the DSS p, q, and g parameters only when L (the modulus length) is not one of the following: 512, 768 and 1024. For those values of L, this implementation uses pre-computed values of p, q, and g given in the document CryptoSpec included in the security guide documentation of the standard JDK distribution.

The DSS requires two primes , p and q, satisfying the following three conditions:

• 2159 < q < 2160
• 2L-1 < p < 2L for a specified L, where L = 512 + 64j for some 0 <= j <= 8
• q divides p - 1.

The algorithm used to find these primes is as described in FIPS-186, section 2.2: GENERATION OF PRIMES. This prime generation scheme starts by using the Sha160 and a user supplied SEED to construct a prime, q, in the range 2¹⁵⁹ < q < 2¹⁶⁰. Once this is accomplished, the same SEED value is used to construct an X in the range 2^L-1 < X < 2^L. The prime, p, is then formed by rounding X to a number congruent to 1 mod 2q. In this implementation we use the same SEED value given in FIPS-186, Appendix 5.