| package org.bouncycastle.asn1.x9; |
| |
| import java.math.BigInteger; |
| |
| import org.bouncycastle.asn1.ASN1Encodable; |
| import org.bouncycastle.asn1.ASN1EncodableVector; |
| import org.bouncycastle.asn1.ASN1OctetString; |
| import org.bouncycastle.asn1.ASN1Sequence; |
| import org.bouncycastle.asn1.DERBitString; |
| import org.bouncycastle.asn1.DERInteger; |
| import org.bouncycastle.asn1.DERObject; |
| import org.bouncycastle.asn1.DERObjectIdentifier; |
| import org.bouncycastle.asn1.DERSequence; |
| import org.bouncycastle.math.ec.ECCurve; |
| |
| /** |
| * ASN.1 def for Elliptic-Curve Curve structure. See |
| * X9.62, for further details. |
| */ |
| public class X9Curve |
| extends ASN1Encodable |
| implements X9ObjectIdentifiers |
| { |
| private ECCurve curve; |
| private byte[] seed; |
| private DERObjectIdentifier fieldIdentifier = null; |
| |
| public X9Curve( |
| ECCurve curve) |
| { |
| this.curve = curve; |
| this.seed = null; |
| setFieldIdentifier(); |
| } |
| |
| public X9Curve( |
| ECCurve curve, |
| byte[] seed) |
| { |
| this.curve = curve; |
| this.seed = seed; |
| setFieldIdentifier(); |
| } |
| |
| public X9Curve( |
| X9FieldID fieldID, |
| ASN1Sequence seq) |
| { |
| fieldIdentifier = fieldID.getIdentifier(); |
| if (fieldIdentifier.equals(prime_field)) |
| { |
| BigInteger p = ((DERInteger)fieldID.getParameters()).getValue(); |
| X9FieldElement x9A = new X9FieldElement(p, (ASN1OctetString)seq.getObjectAt(0)); |
| X9FieldElement x9B = new X9FieldElement(p, (ASN1OctetString)seq.getObjectAt(1)); |
| curve = new ECCurve.Fp(p, x9A.getValue().toBigInteger(), x9B.getValue().toBigInteger()); |
| } |
| else |
| { |
| if (fieldIdentifier.equals(characteristic_two_field)) |
| { |
| // Characteristic two field |
| DERSequence parameters = (DERSequence)fieldID.getParameters(); |
| int m = ((DERInteger)parameters.getObjectAt(0)).getValue(). |
| intValue(); |
| DERObjectIdentifier representation |
| = (DERObjectIdentifier)parameters.getObjectAt(1); |
| |
| int k1 = 0; |
| int k2 = 0; |
| int k3 = 0; |
| if (representation.equals(tpBasis)) |
| { |
| // Trinomial basis representation |
| k1 = ((DERInteger)parameters.getObjectAt(2)).getValue(). |
| intValue(); |
| } |
| else |
| { |
| // Pentanomial basis representation |
| DERSequence pentanomial |
| = (DERSequence)parameters.getObjectAt(2); |
| k1 = ((DERInteger)pentanomial.getObjectAt(0)).getValue(). |
| intValue(); |
| k2 = ((DERInteger)pentanomial.getObjectAt(1)).getValue(). |
| intValue(); |
| k3 = ((DERInteger)pentanomial.getObjectAt(2)).getValue(). |
| intValue(); |
| } |
| X9FieldElement x9A = new X9FieldElement(m, k1, k2, k3, (ASN1OctetString)seq.getObjectAt(0)); |
| X9FieldElement x9B = new X9FieldElement(m, k1, k2, k3, (ASN1OctetString)seq.getObjectAt(1)); |
| // TODO Is it possible to get the order (n) and cofactor(h) too? |
| curve = new ECCurve.F2m(m, k1, k2, k3, x9A.getValue().toBigInteger(), x9B.getValue().toBigInteger()); |
| } |
| } |
| |
| if (seq.size() == 3) |
| { |
| seed = ((DERBitString)seq.getObjectAt(2)).getBytes(); |
| } |
| } |
| |
| private void setFieldIdentifier() |
| { |
| if (curve instanceof ECCurve.Fp) |
| { |
| fieldIdentifier = prime_field; |
| } |
| else if (curve instanceof ECCurve.F2m) |
| { |
| fieldIdentifier = characteristic_two_field; |
| } |
| else |
| { |
| throw new IllegalArgumentException("This type of ECCurve is not " |
| + "implemented"); |
| } |
| } |
| |
| public ECCurve getCurve() |
| { |
| return curve; |
| } |
| |
| public byte[] getSeed() |
| { |
| return seed; |
| } |
| |
| /** |
| * Produce an object suitable for an ASN1OutputStream. |
| * <pre> |
| * Curve ::= SEQUENCE { |
| * a FieldElement, |
| * b FieldElement, |
| * seed BIT STRING OPTIONAL |
| * } |
| * </pre> |
| */ |
| public DERObject toASN1Object() |
| { |
| ASN1EncodableVector v = new ASN1EncodableVector(); |
| |
| if (fieldIdentifier.equals(prime_field)) |
| { |
| v.add(new X9FieldElement(curve.getA()).getDERObject()); |
| v.add(new X9FieldElement(curve.getB()).getDERObject()); |
| } |
| else if (fieldIdentifier.equals(characteristic_two_field)) |
| { |
| v.add(new X9FieldElement(curve.getA()).getDERObject()); |
| v.add(new X9FieldElement(curve.getB()).getDERObject()); |
| } |
| |
| if (seed != null) |
| { |
| v.add(new DERBitString(seed)); |
| } |
| |
| return new DERSequence(v); |
| } |
| } |