org.bouncycastle.tls.DefaultTlsDHConfigVerifier Maven / Gradle / Ivy

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The Bouncy Castle Java APIs for the TLS, including a JSSE provider. The APIs are designed primarily to be used in conjunction with the BC FIPS provider. The APIs may also be used with other providers although if being used in a FIPS context it is the responsibility of the user to ensure that any other providers used are FIPS certified and used appropriately.

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package org.bouncycastle.tls;

import java.math.BigInteger;
import java.util.Vector;

import org.bouncycastle.tls.crypto.DHGroup;
import org.bouncycastle.tls.crypto.DHStandardGroups;
import org.bouncycastle.tls.crypto.TlsDHConfig;

public class DefaultTlsDHConfigVerifier
    implements TlsDHConfigVerifier
{
    public static final int DEFAULT_MINIMUM_PRIME_BITS = 2048;

    protected static final Vector DEFAULT_GROUPS = new Vector();

    private static void addDefaultGroup(DHGroup dhGroup)
    {
        DEFAULT_GROUPS.addElement(dhGroup);
    }

    static
    {
        addDefaultGroup(DHStandardGroups.rfc7919_ffdhe2048);
        addDefaultGroup(DHStandardGroups.rfc7919_ffdhe3072);
        addDefaultGroup(DHStandardGroups.rfc7919_ffdhe4096);
        addDefaultGroup(DHStandardGroups.rfc7919_ffdhe6144);
        addDefaultGroup(DHStandardGroups.rfc7919_ffdhe8192);

        addDefaultGroup(DHStandardGroups.rfc3526_1536);
        addDefaultGroup(DHStandardGroups.rfc3526_2048);
        addDefaultGroup(DHStandardGroups.rfc3526_3072);
        addDefaultGroup(DHStandardGroups.rfc3526_4096);
        addDefaultGroup(DHStandardGroups.rfc3526_6144);
        addDefaultGroup(DHStandardGroups.rfc3526_8192);
    }

    // Vector is (DHGroup)
    protected Vector groups;
    protected int minimumPrimeBits;

    /**
     * Accept named groups and various standard DH groups with 'P' at least {@link #DEFAULT_MINIMUM_PRIME_BITS} bits.
     */
    public DefaultTlsDHConfigVerifier()
    {
        this(DEFAULT_MINIMUM_PRIME_BITS);
    }

    /**
     * Accept named groups and various standard DH groups with 'P' at least the specified number of bits.
     */
    public DefaultTlsDHConfigVerifier(int minimumPrimeBits)
    {
        this(DEFAULT_GROUPS, minimumPrimeBits);
    }

    /**
     * Accept named groups and a custom set of group parameters, subject to a minimum bitlength for 'P'.
     * 
     * @param groups a {@link Vector} of acceptable {@link DHGroup}s.
     */
    public DefaultTlsDHConfigVerifier(Vector groups, int minimumPrimeBits)
    {
        this.groups = groups;
        this.minimumPrimeBits = minimumPrimeBits;
    }

    public boolean accept(TlsDHConfig dhConfig)
    {
        return checkMinimumPrimeBits(dhConfig) && checkGroup(dhConfig);
    }

    public int getMinimumPrimeBits()
    {
        return minimumPrimeBits;
    }

    protected boolean areGroupsEqual(DHGroup a, DHGroup b)
    {
        return a == b || (areParametersEqual(a.getP(), b.getP()) && areParametersEqual(a.getG(), b.getG()));
    }

    protected boolean areParametersEqual(BigInteger a, BigInteger b)
    {
        return a == b || a.equals(b);
    }

    protected boolean checkGroup(TlsDHConfig dhConfig)
    {
        if (NamedGroup.refersToASpecificFiniteField(dhConfig.getNamedGroup()))
        {
            return true;
        }

        DHGroup explicitGroup = dhConfig.getExplicitGroup();
        for (int i = 0; i < groups.size(); ++i)
        {
            if (areGroupsEqual(explicitGroup, (DHGroup)groups.elementAt(i)))
            {
                return true;
            }
        }
        return false;
    }

    protected boolean checkMinimumPrimeBits(TlsDHConfig dhConfig)
    {
        int bits = getMinimumPrimeBits();

        int namedGroup = dhConfig.getNamedGroup();
        if (namedGroup >= 0)
        {
            return NamedGroup.getFiniteFieldBits(namedGroup) >= bits;
        }

        DHGroup explicitGroup = dhConfig.getExplicitGroup();
        return explicitGroup.getP().bitLength() >= bits;
    }
}