net.i2p.crypto.eddsa.math.bigint

Class BigIntegerScalarOps

java.lang.Object

net.i2p.crypto.eddsa.math.bigint.BigIntegerScalarOps

All Implemented Interfaces:

ScalarOps

public class BigIntegerScalarOps
extends java.lang.Object
implements ScalarOps

Field Summary

Fields

Modifier and Type	Field and Description
private BigIntegerLittleEndianEncoding	enc
private java.math.BigInteger	l

Constructor Summary

Constructors

Constructor and Description
BigIntegerScalarOps(Field f, java.math.BigInteger l)

Method Summary

Modifier and Type	Method and Description
byte[]	multiplyAndAdd(byte[] a, byte[] b, byte[] c) $r = (a * b + c) \bmod l$
byte[]	reduce(byte[] s) Reduce the given scalar mod $l$.

Methods inherited from class java.lang.Object

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

Field Detail

l

private final java.math.BigInteger l

enc

private final BigIntegerLittleEndianEncoding enc

Constructor Detail

BigIntegerScalarOps

public BigIntegerScalarOps(Field f,
                           java.math.BigInteger l)

Method Detail

reduce

public byte[] reduce(byte[] s)

Description copied from interface: ScalarOps

Reduce the given scalar mod $l$.

From the Ed25519 paper:
Here we interpret $2b$-bit strings in little-endian form as integers in $\{0, 1,..., 2^{(2b)}-1\}$.

Specified by:

reduce in interface ScalarOps

Parameters:

s - the scalar to reduce

Returns:

$s \bmod l$

multiplyAndAdd

public byte[] multiplyAndAdd(byte[] a,
                             byte[] b,
                             byte[] c)

Description copied from interface: ScalarOps

$r = (a * b + c) \bmod l$

Specified by:

multiplyAndAdd in interface ScalarOps

Parameters:

a - a scalar

b - a scalar

c - a scalar

Returns:

$(a*b + c) \bmod l$