io.nem.core.crypto.ed25519.arithmetic

Class Ed25519EncodedFieldElement

java.lang.Object

io.nem.core.crypto.ed25519.arithmetic.Ed25519EncodedFieldElement

public class Ed25519EncodedFieldElement
extends java.lang.Object

Represents a field element of the finite field with p=2^255-19 elements. The value of the field element is held in 2^8 bit representation, i.e. in a byte array. The length of the array must be 32 or 64.

Constructor Summary

Constructors

Constructor and Description
Ed25519EncodedFieldElement(byte[] values) Creates a new encoded field element.

Method Summary

Modifier and Type	Method and Description
Ed25519FieldElement	decode() Decodes this encoded (32 byte) representation to a field element in its 10 byte 2^25.5 representation.
boolean	equals(java.lang.Object obj)
byte[]	getRaw() Gets the underlying byte array.
int	hashCode()
boolean	isNegative() Return true if this is in {1,3,5,...,q-2} Return false if this is in {0,2,4,...,q-1} Preconditions: |x| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.
boolean	isNonZero() Gets a value indicating whether or not the field element is non-zero.
Ed25519EncodedFieldElement	modQ() Reduces this encoded field element (64 bytes) modulo the group order q.
Ed25519EncodedFieldElement	multiplyAndAddModQ(Ed25519EncodedFieldElement b, Ed25519EncodedFieldElement c) Multiplies this encoded field element with another and adds a third.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Ed25519EncodedFieldElement

public Ed25519EncodedFieldElement(byte[] values)

Creates a new encoded field element.

Parameters:

values - The byte array that holds the values.

Method Detail

getRaw

public byte[] getRaw()

Gets the underlying byte array.

Returns:

The byte array.

isNegative

public boolean isNegative()

Return true if this is in {1,3,5,...,q-2} Return false if this is in {0,2,4,...,q-1}
Preconditions: |x| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc.

Returns:

true if this is in {1,3,5,...,q-2}, false otherwise.

isNonZero

public boolean isNonZero()

Gets a value indicating whether or not the field element is non-zero.

Returns:

1 if it is non-zero, 0 otherwise.

decode

public Ed25519FieldElement decode()

Decodes this encoded (32 byte) representation to a field element in its 10 byte 2^25.5 representation. The most significant bit is discarded.

Returns:

The field element in its 2^25.5 bit representation.

modQ

public Ed25519EncodedFieldElement modQ()

Reduces this encoded field element (64 bytes) modulo the group order q.

Returns:

Encoded field element (32 bytes).

multiplyAndAddModQ

public Ed25519EncodedFieldElement multiplyAndAddModQ(Ed25519EncodedFieldElement b,
                                                     Ed25519EncodedFieldElement c)

Multiplies this encoded field element with another and adds a third. The result is reduced modulo the group order.
See the comments in the method modQ() for an explanation of the algorithm.

Parameters:

b - The encoded field element which is multiplied with this.

c - The third encoded field element which is added.

Returns:

The encoded field element (32 bytes).

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object