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The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. 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.

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package org.bouncycastle.operator;

import java.math.BigInteger;

import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.util.Arrays;

/**
 * RFC 7914 scrypt parameters.
 *
 *  * scrypt-params ::= SEQUENCE {
 *      salt OCTET STRING,
 *      costParameter INTEGER (1..MAX),
 *      blockSize INTEGER (1..MAX),
 *      parallelizationParameter INTEGER (1..MAX),
 *      keyLength INTEGER (1..MAX) OPTIONAL
 * }
 * 
 */
public class ScryptParams
    extends ASN1Object
{
    private final byte[] salt;
    private final BigInteger costParameter;
    private final BigInteger blockSize;
    private final BigInteger parallelizationParameter;
    private final BigInteger keyLength;

    public ScryptParams(byte[] salt, int costParameter, int blockSize, int parallelizationParameter)
    {
        this(salt, BigInteger.valueOf(costParameter), BigInteger.valueOf(blockSize), BigInteger.valueOf(parallelizationParameter), null);
    }

    public ScryptParams(byte[] salt, int costParameter, int blockSize, int parallelizationParameter, int keyLength)
    {
        this(salt, BigInteger.valueOf(costParameter), BigInteger.valueOf(blockSize), BigInteger.valueOf(parallelizationParameter), BigInteger.valueOf(keyLength));
    }
    
    /**
     * Base constructor.
     *
     * @param salt salt value
     * @param costParameter specifies the CPU/Memory cost parameter N
     * @param blockSize block size parameter r
     * @param parallelizationParameter parallelization parameter
     * @param keyLength length of key to be derived (in octects)
     */
    public ScryptParams(byte[] salt, BigInteger costParameter, BigInteger blockSize, BigInteger parallelizationParameter, BigInteger keyLength)
    {
        this.salt = Arrays.clone(salt);
        this.costParameter = costParameter;
        this.blockSize = blockSize;
        this.parallelizationParameter = parallelizationParameter;
        this.keyLength = keyLength;
    }

    public static ScryptParams getInstance(
        Object  o)
    {
        if (o instanceof ScryptParams)
        {
            return (ScryptParams)o;
        }
        else if (o != null)
        {
            return new ScryptParams(ASN1Sequence.getInstance(o));
        }

        return null;
    }

    private ScryptParams(ASN1Sequence seq)
    {
        if (seq.size() != 4 && seq.size() != 5)
        {
            throw new IllegalArgumentException("invalid sequence: size = " + seq.size());
        }

        this.salt = Arrays.clone(ASN1OctetString.getInstance(seq.getObjectAt(0)).getOctets());
        this.costParameter = ASN1Integer.getInstance(seq.getObjectAt(1)).getValue();
        this.blockSize = ASN1Integer.getInstance(seq.getObjectAt(2)).getValue();
        this.parallelizationParameter = ASN1Integer.getInstance(seq.getObjectAt(3)).getValue();

        if (seq.size() == 5)
        {
            this.keyLength = ASN1Integer.getInstance(seq.getObjectAt(4)).getValue();
        }
        else
        {
            this.keyLength = null;
        }
    }

    public byte[] getSalt()
    {
        return Arrays.clone(salt);
    }

    public BigInteger getCostParameter()
    {
        return costParameter;
    }

    public BigInteger getBlockSize()
    {
        return blockSize;
    }

    public BigInteger getParallelizationParameter()
    {
        return parallelizationParameter;
    }

    /**
     * Return the length in octets for the derived key.
     *
     * @return length for key to be derived (in octets)
     */
    public BigInteger getKeyLength()
    {
        return keyLength;
    }

    public ASN1Primitive toASN1Primitive()
    {
        ASN1EncodableVector v = new ASN1EncodableVector();

        v.add(new DEROctetString(salt));
        v.add(new ASN1Integer(costParameter));
        v.add(new ASN1Integer(blockSize));
        v.add(new ASN1Integer(parallelizationParameter));
        if (keyLength != null)
        {
            v.add(new ASN1Integer(keyLength));
        }

        return new DERSequence(v);
    }
}