falcon.h File Reference

Contains the primary public api for the Falcon asymmetric signature scheme implementation. More...

#include "qsccommon.h"

Go to the source code of this file.

Macros
#define	QSC_FALCON_PRIVATEKEY_SIZE   2305
	The byte size of the secret private-key array.
#define	QSC_FALCON_PUBLICKEY_SIZE   1793
	The byte size of the public-key array.
#define	QSC_FALCON_SIGNATURE_SIZE   1276
	The byte size of the signature array.
#define	QSC_FALCON_ALGNAME   "FALCON"
	The formal algorithm name.

Functions
QSC_EXPORT_API bool	qsc_falcon_generate_keypair (uint8_t *publickey, uint8_t *privatekey, bool(*rng_generate)(uint8_t *, size_t))
	Generates a Falcon public/private key-pair.
QSC_EXPORT_API bool	qsc_falcon_sign (uint8_t *signedmsg, size_t *smsglen, const uint8_t *message, size_t msglen, const uint8_t *privatekey, bool(*rng_generate)(uint8_t *, size_t))
	Takes the message as input and returns an array containing the signature followed by the message.
QSC_EXPORT_API bool	qsc_falcon_verify (uint8_t *message, size_t *msglen, const uint8_t *signedmsg, size_t smsglen, const uint8_t *publickey)
	Verifies a signature-message pair with the public key.

Detailed Description

Contains the primary public api for the Falcon asymmetric signature scheme implementation.

Example

// An example of key-pair creation, encryption, and decryption
#define MSGLEN 32
uint8_t pk[QSC_FALCON_PUBLICKEY_SIZE];
uint8_t sk[QSC_FALCON_SECRETKEY_SIZE];
uint8_t msg[32];
uint8_t smsg[QSC_FALCON_SIGNATURE_SIZE + MSGLEN];
uint8_t rmsg[32];
 
uint32_t rmsglen = 0;
uint32_t smsglen = 0;
 
// create the public and secret keys
qsc_falcon_generate(pk, sk);
// returns the signed the message in smsg
qsc_falcon_sign(smsg, &smsglen, msg, MSGLEN, sk);
// test the signature and return the message bytes in rmsg
if (qsc_falcon_verify(rmsg, &rmsglen, smsg, smsglen, pk) != true)
{
    // authentication failed, do something..
}

Based entirely on the C reference branch of Falcon taken from the NIST Post Quantum Competition Round 3 submission.
The NIST Post Quantum Competition Round 3 Finalists.
The Falcon website.
The Falcon Algorithm Specification.

Function Documentation

qsc_falcon_generate_keypair()

QSC_EXPORT_API bool qsc_falcon_generate_keypair	(	uint8_t *	publickey,
		uint8_t *	privatekey,
		bool(*	rng_generate )(uint8_t *, size_t) )

Generates a Falcon public/private key-pair.

Warning

Arrays must be sized to QSC_FALCON_PUBLICKEY_SIZE and QSC_FALCON_SECRETKEY_SIZE.

Parameters

publickey	Pointer to the public verification-key array
privatekey	Pointer to the private signature-key array
rng_generate	Pointer to the random generator

Returns

Returns true for success

qsc_falcon_sign()

QSC_EXPORT_API bool qsc_falcon_sign	(	uint8_t *	signedmsg,
		size_t *	smsglen,
		const uint8_t *	message,
		size_t	msglen,
		const uint8_t *	privatekey,
		bool(*	rng_generate )(uint8_t *, size_t) )

Takes the message as input and returns an array containing the signature followed by the message.

Warning

Signature array must be sized to the size of the message plus QSC_FALCON_SIGNATURE_SIZE.

Parameters

signedmsg	Pointer to the signed-message array
smsglen	The signed message length
message	[const] Pointer to the message array
msglen	The message array length
privatekey	[const] Pointer to the private signature-key
rng_generate	Pointer to the random generator

Returns

Returns true for success

qsc_falcon_verify()

QSC_EXPORT_API bool qsc_falcon_verify	(	uint8_t *	message,
		size_t *	msglen,
		const uint8_t *	signedmsg,
		size_t	smsglen,
		const uint8_t *	publickey )

Verifies a signature-message pair with the public key.

Parameters

message	Pointer to the message output array
msglen	Length of the message array
signedmsg	[const] Pointer to the signed message array
smsglen	The signed message length
publickey	[const] Pointer to the public verification-key array

Returns

Returns true for success