primefld25519.h File Reference

Documentation file for the prime field 25519 APIs. More...

Go to the source code of this file.

Functions
MOC_EXTERN MSTATUS	PF_25519_from_bytes (sbyte4 *pResult, const ubyte *pInput, byteBoolean compareToThePrime)
	Converts a Little Endian byte array representing a finite field element into an element in sbyte4 word array form. More...
MOC_EXTERN byteBoolean	PF_25519_match (const sbyte4 *pA, const sbyte4 *pB)
	Tests if two finite field elements (encoded as sbyte4 word arrays) actually represent the same element. More...
MOC_EXTERN void	PF_25519_multiply (sbyte4 *pResult, const sbyte4 *pA, const sbyte4 *pB)
	Multiplies two finite field elements. More...
MOC_EXTERN MSTATUS	PF_25519_specialExp (sbyte4 *pResult, const sbyte4 *pA, const byteBoolean isInverse)
	Performs a finite field exponentiation that can be used to compute the inverse of an element or a partial result needed for a square root computation. More...
MOC_EXTERN void	PF_25519_square (sbyte4 *pResult, const sbyte4 *pA)
	Squares a finite field elements. More...
MOC_EXTERN void	PF_25519_to_bytes (ubyte *pResult, sbyte4 *pA)
	Converts a finite field element stored as an sbyte4 word array into a Little Endian byte array representing a reduced element mod p. More...

Detailed Description

Documentation file for the prime field 25519 APIs. This is the prime field with 2^255 - 19 elements.

To enable the methods in this file one must define

• __ENABLE_MOCANA_ECC__ and at least one or more of the following flags
• __ENABLE_MOCANA_ECC_EDDH_25519__
• __ENABLE_MOCANA_ECC_EDDSA_25519__

primefld25519.h

Function Documentation

PF_25519_from_bytes()

MOC_EXTERN MSTATUS PF_25519_from_bytes	(	sbyte4 *	pResult,
		const ubyte *	pInput,
		byteBoolean	compareToThePrime
	)

Parameters

pResult	Pointer to the resulting word array form of the element.
pInput	The input element in Little Endian byte array form. This must be 32 bytes.
compareToThePrime	If TRUE then the input element will be checked that it is less than the prime p. If FALSE then no validation check is done.

Returns

OK (0) if successful, otherwise a negative number error code from merrors.h

PF_25519_match()

MOC_EXTERN byteBoolean PF_25519_match	(	const sbyte4 *	pA,
		const sbyte4 *	pB
	)

Parameters

pA	The first element.
pB	The second element.

Returns

TRUE if pA and pB represent the same finite field element. FALSE otherwise.

PF_25519_multiply()

MOC_EXTERN void PF_25519_multiply	(	sbyte4 *	pResult,
		const sbyte4 *	pA,
		const sbyte4 *	pB
	)

The absolute value of the words of pA and pB must be 27 bits or less. pA and pB are allowed to be the same pointer but one should use the more efficient PF_25519_square method in that case. The result will have words that will be 26 bits or less in absolute value. pResult is allowed to be the same pointer as pA or pB.

Parameters

pResult	Buffer to hold the resulting element.
pA	The first input element.
pB	The second input element.

PF_25519_specialExp()

MOC_EXTERN MSTATUS PF_25519_specialExp	(	sbyte4 *	pResult,
		const sbyte4 *	pA,
		const byteBoolean	isInverse
	)

Parameters

pResult	Buffer to hold the resulting element.
pA	The input element.
isInverse	If TRUE then pA^-1 = pA^(p-2) is calculated. If FALSE then pA^((p-5)/8)) is calculated.

Returns

OK (0) if successful, otherwise a negative number error code from merrors.h

PF_25519_square()

MOC_EXTERN void PF_25519_square	(	sbyte4 *	pResult,
		const sbyte4 *	pA
	)

The absolute value of the words of pA must be 27 bits or less. The result will have words that will be 26 bits or less in absolute value. pResult is allowed to be the same pointer as pA.

Parameters

pResult	Buffer to hold the resulting element.
pA	The input element.

PF_25519_to_bytes()

MOC_EXTERN void PF_25519_to_bytes	(	ubyte *	pResult,
		sbyte4 *	pA
	)

The input element must consist of all words that are 26 bits or less in absolute value.

Parameters

pResult	Buffer that will hold the resulting reduced element. This must be 32 bytes in length.
pA	The input element. This value will be mangled.

Warning

This method mangles the input value pA. If use of pA is needed again you must make another copy before calling this method.