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package org.bouncycastle.asn1.x9;
import java.math.BigInteger;
import java.util.Enumeration;
import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERSequence;
/**
* X9.44 Diffie-Hellman domain parameters.
* <pre>
* DomainParameters ::= SEQUENCE {
* p INTEGER, -- odd prime, p=jq +1
* g INTEGER, -- generator, g
* q INTEGER, -- factor of p-1
* j INTEGER OPTIONAL, -- subgroup factor, j >= 2
* validationParams ValidationParams OPTIONAL
* }
* </pre>
*/
public class DomainParameters
extends ASN1Object
{
private final ASN1Integer p, g, q, j;
private final ValidationParams validationParams;
/**
* Return a DomainParameters object from the passed in tagged object.
*
* @param obj a tagged object.
* @param explicit true if the contents of the object is explictly tagged, false otherwise.
* @return a DomainParameters
*/
public static DomainParameters getInstance(ASN1TaggedObject obj, boolean explicit)
{
return getInstance(ASN1Sequence.getInstance(obj, explicit));
}
/**
* Return a DomainParameters object from the passed in object.
*
* @param obj an object for conversion or a byte[].
* @return a DomainParameters
*/
public static DomainParameters getInstance(Object obj)
{
if (obj instanceof DomainParameters)
{
return (DomainParameters)obj;
}
else if (obj != null)
{
return new DomainParameters(ASN1Sequence.getInstance(obj));
}
return null;
}
/**
* Base constructor - the full domain parameter set.
*
* @param p the prime p defining the Galois field.
* @param g the generator of the multiplicative subgroup of order g.
* @param q specifies the prime factor of p - 1
* @param j optionally specifies the value that satisfies the equation p = jq+1
* @param validationParams parameters for validating these domain parameters.
*/
public DomainParameters(BigInteger p, BigInteger g, BigInteger q, BigInteger j,
ValidationParams validationParams)
{
if (p == null)
{
throw new IllegalArgumentException("'p' cannot be null");
}
if (g == null)
{
throw new IllegalArgumentException("'g' cannot be null");
}
if (q == null)
{
throw new IllegalArgumentException("'q' cannot be null");
}
this.p = new ASN1Integer(p);
this.g = new ASN1Integer(g);
this.q = new ASN1Integer(q);
if (j != null)
{
this.j = new ASN1Integer(j);
}
else
{
this.j = null;
}
this.validationParams = validationParams;
}
private DomainParameters(ASN1Sequence seq)
{
if (seq.size() < 3 || seq.size() > 5)
{
throw new IllegalArgumentException("Bad sequence size: " + seq.size());
}
Enumeration e = seq.getObjects();
this.p = ASN1Integer.getInstance(e.nextElement());
this.g = ASN1Integer.getInstance(e.nextElement());
this.q = ASN1Integer.getInstance(e.nextElement());
ASN1Encodable next = getNext(e);
if (next != null && next instanceof ASN1Integer)
{
this.j = ASN1Integer.getInstance(next);
next = getNext(e);
}
else
{
this.j = null;
}
if (next != null)
{
this.validationParams = ValidationParams.getInstance(next.toASN1Primitive());
}
else
{
this.validationParams = null;
}
}
private static ASN1Encodable getNext(Enumeration e)
{
return e.hasMoreElements() ? (ASN1Encodable)e.nextElement() : null;
}
/**
* Return the prime p defining the Galois field.
*
* @return the prime p.
*/
public BigInteger getP()
{
return this.p.getPositiveValue();
}
/**
* Return the generator of the multiplicative subgroup of order g.
*
* @return the generator g.
*/
public BigInteger getG()
{
return this.g.getPositiveValue();
}
/**
* Return q, the prime factor of p - 1
*
* @return q value
*/
public BigInteger getQ()
{
return this.q.getPositiveValue();
}
/**
* Return the value that satisfies the equation p = jq+1 (if present).
*
* @return j value or null.
*/
public BigInteger getJ()
{
if (this.j == null)
{
return null;
}
return this.j.getPositiveValue();
}
/**
* Return the validation parameters for this set (if present).
*
* @return validation parameters, or null if absent.
*/
public ValidationParams getValidationParams()
{
return this.validationParams;
}
/**
* Return an ASN.1 primitive representation of this object.
*
* @return a DERSequence containing the parameter values.
*/
public ASN1Primitive toASN1Primitive()
{
ASN1EncodableVector v = new ASN1EncodableVector();
v.add(this.p);
v.add(this.g);
v.add(this.q);
if (this.j != null)
{
v.add(this.j);
}
if (this.validationParams != null)
{
v.add(this.validationParams);
}
return new DERSequence(v);
}
}
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