com.safenetinc.luna.provider.param

Class LunaECUtils

java.lang.Object

com.safenetinc.luna.provider.param.LunaECUtils

public class LunaECUtils
extends Object

Various static elliptic curve utility methods

Constructor Summary

Constructors

Constructor and Description
LunaECUtils()

Method Summary

Modifier and Type	Method and Description
static BigInteger	bi(String s) Convert the given String representing a hexadecimal number into a BigInteger.
static ECPoint	decodePoint(byte[] data, EllipticCurve curve) Converts the a byte representation of a point on the given elliptic curve into an ECPoint object.
static byte[]	encodePoint(ECPoint point, EllipticCurve curve) Converts an ECPoint on the given elliptic curve into an ASN.1-encoded octet string (as required by the Luna hardware).
static byte[]	encodePointNoAsn(ECPoint point, EllipticCurve curve) Converts an ECPoint on the given elliptic curve into a byte array as specified in SEC1 2.3.3.
static String	getCurveCommonName(ECParameterSpec params) Given a set of parameters, returns the common name of the curve (ex.
static String	getCurveName(ECParameterSpec params) Given a set of parameters, returns the a String representation of the curve's OID (ex.
static int	getFieldSize(ECParameterSpec spec) Return the field size of the curve defined by the given spec
static int	getRawSignatureSize(ECKey key) Returns the size of a raw ECDSA signature generated on the HSM for the given key.
static boolean	isCompressed(byte[] point) Detects if a given encoded EC point is using compressed notation.

Methods inherited from class java.lang.Object

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

Constructor Detail

LunaECUtils

public LunaECUtils()

Method Detail

decodePoint

public static ECPoint decodePoint(byte[] data,
                                  EllipticCurve curve)

Converts the a byte representation of a point on the given elliptic curve into an ECPoint object. The Luna hardware implementation stores these points in ASN.1-encoded format, so the first operation is to find the length of the ASN.1 header. The byte array from this offset onwards is then decoded as specified in SEC1 2.3.4.

Parameters:

data - The ASN.1-encoded byte representation of an EC point

curve - The curve on which the point resides

Returns:

An ECPoint representation of the EC point

Throws:

LunaException - If the encoded point is invalid in any way

encodePointNoAsn

public static byte[] encodePointNoAsn(ECPoint point,
                                      EllipticCurve curve)

Converts an ECPoint on the given elliptic curve into a byte array as specified in SEC1 2.3.3.

Parameters:

point - The ECPoint to convert

curve - The curve on which the point resides

Returns:

A binary-encoded version of the ECPoint as per SEC1 2.3.3

encodePoint

public static byte[] encodePoint(ECPoint point,
                                 EllipticCurve curve)

Converts an ECPoint on the given elliptic curve into an ASN.1-encoded octet string (as required by the Luna hardware). The first operation is to convert the point into a byte array as specified in SEC1 2.3.3. Then we add an ASN.1 header and return the resulting array.

Parameters:

point - The ECPoint to convert

curve - The curve on which the point resides

Returns:

An ASN.1-encoded octet string representation of the EC point

isCompressed

public static boolean isCompressed(byte[] point)

Detects if a given encoded EC point is using compressed notation. This method will return true if the leading byte of the encoded point is 0x02 or 0x03. Invalid points (encoding too long, or leading byte outside the 0x00-0x04 range) are not detected.

Parameters:

point - The encoded point

Returns:

true if the point is compressed

getCurveName

public static String getCurveName(ECParameterSpec params)

Given a set of parameters, returns the a String representation of the curve's OID (ex. "1.3.132.0.6" for secp112r1 or "1.2.840.10045.3.0.20" for X9.62 c2tnb431r1)

Parameters:

params - The EC parameter spec to examine

Returns:

The OID of the curve, as a String

getCurveCommonName

public static String getCurveCommonName(ECParameterSpec params)

Given a set of parameters, returns the common name of the curve (ex. "secp112r1" or "c2tnb431r1"

Parameters:

params - The EC parameter spec to examine

Returns:

The common name of the curve

bi

public static BigInteger bi(String s)

Convert the given String representing a hexadecimal number into a BigInteger.

Parameters:

s - String representation of a hexadecimal number

Returns:

BigInteger representation of the given hex number

getFieldSize

public static int getFieldSize(ECParameterSpec spec)

Return the field size of the curve defined by the given spec

Parameters:

spec - the JCA specification object

Returns:

The field size of the curve

getRawSignatureSize

public static int getRawSignatureSize(ECKey key)

Returns the size of a raw ECDSA signature generated on the HSM for the given key. The signature size is based on the order of the EC curve, so any key on the same curve as key will have the same signature size.

Note that the final ECDSA signature will include ASN.1 encoding which is not figured into this total.

Parameters:

key - the key to analyze

Returns:

the size of a raw ECDSA signature using the given key