Field Detail

• f

  protected Field f

Constructor Detail

• Encoding

  public Encoding()

Method Detail

• setField

  public void setField​(Field f)

• encode

  public abstract byte[] encode​(FieldElement x)

  Encode a FieldElement in its (b-1)-bit encoding.

  Returns:

  the (b-1)-bit encoding of this FieldElement.

• decode

  public abstract FieldElement decode​(byte[] in)

  Decode a FieldElement from its (b-1)-bit encoding. The highest bit is masked out.

  Parameters:

  in - the (b-1)-bit encoding of a FieldElement.

  Returns:

  the FieldElement represented by 'val'.

• isNegative

  public abstract boolean isNegative​(FieldElement x)

  From the Ed25519 paper:
  x is negative if the (b-1)-bit encoding of x is lexicographically larger than the (b-1)-bit encoding of -x. If q is an odd prime and the encoding is the little-endian representation of {0, 1,..., q-1} then the negative elements of F_q are {1, 3, 5,..., q-2}.

  Returns:

  true if negative