iaik.security.ec.math.curve

Interface PointCompressorDecompressor

public interface PointCompressorDecompressor

Interface specifying a point compressor/decompressor.

Author:

Christian Hanser

Field Summary

Fields

Modifier and Type	Field and Description
static byte	PC_COMPRESSED The bit mask for compressed points.
static byte	PC_UNCOMPRESSED The bit mask for uncompressed points.

Method Summary

Modifier and Type	Method and Description
ECPoint	decode(byte[] encodedPoint) Decompresses a compressed point.
ECPoint	decode(byte[] encodedPoint, int length) Decompresses a compressed point.
byte[]	encode(ECPoint p) Compresses a point, i.e.

Field Detail

PC_COMPRESSED

static final byte PC_COMPRESSED

The bit mask for compressed points. Used as first byte in the encoded form.

PC_UNCOMPRESSED

static final byte PC_UNCOMPRESSED

The bit mask for uncompressed points. Used as first byte in the encoded form.

Method Detail

encode

byte[] encode(ECPoint p)

Compresses a point, i.e. converts it to a byte[], where only one bit is used to represent the y-coordinate.

Parameters:

p - the point to be compressed.

Returns:

a byte[] holding the compressed point

decode

ECPoint decode(byte[] encodedPoint)
        throws DecodingException

Decompresses a compressed point.

Parameters:

encodedPoint - the byte[]-encoding of the point

Returns:

the decompressed point

Throws:

DecodingException - if the point could not be decoded

decode

ECPoint decode(byte[] encodedPoint,
               int length)
        throws DecodingException

Decompresses a compressed point.

Parameters:

encodedPoint - the byte[]-encoding of the point

length - the length of the sub-array to be considered

Returns:

the decompressed point

Throws:

DecodingException - if the point could not be decoded