ecdhp384base.h File Reference

Elliptic Curve Diffie-Hellman over the NIST P-384 domain. More...

#include "qsccommon.h"

Go to the source code of this file.

Macros
#define	QSC_ECDHP384_PUBLICKEY_SIZE   96U
#define	QSC_ECDHP384_PRIVATEKEY_SIZE   48U
	The byte size of a P-384 private key.
#define	QSC_ECDHP384_SHAREDSECRET_SIZE   48U
	The byte size of the derived P-384 shared secret.
#define	QSC_ECDHP384_SEED_SIZE   48U
	The byte size of the deterministic seed used to derive a P-384 key-pair.

Functions
QSC_EXPORT_API void	qsc_p384_public_from_private (uint8_t *publickey, const uint8_t *privatekey)
	Derive a serialized P-384 public key from a private key.
QSC_EXPORT_API void	qsc_p384_generate_keypair (uint8_t *publickey, uint8_t *privatekey, bool(*rng_generate)(uint8_t *, size_t))
	Generate a random P-384 public and private key-pair.
QSC_EXPORT_API void	qsc_p384_generate_seeded_keypair (uint8_t *publickey, uint8_t *privatekey, const uint8_t *seed)
	Generate a deterministic P-384 public and private key-pair from a seed.
QSC_EXPORT_API bool	qsc_p384_key_exchange (uint8_t *secret, const uint8_t *publickey, const uint8_t *privatekey)
	Derive a P-384 shared secret using a peer public key and a local private key.

Detailed Description

Elliptic Curve Diffie-Hellman over the NIST P-384 domain.

This header exposes the low-level public interface for the QSC P-384 Elliptic Curve Diffie-Hellman implementation. The functions in this module provide private to public key derivation, random or seed-based key-pair generation, and shared secret derivation using a peer public key and a local private key.

The public key is encoded as a fixed-size byte array of QSC_ECDHP384_PUBLICKEY_SIZE bytes. The private key, shared secret, and deterministic seed are each encoded as fixed-size byte arrays of their respective constant sizes.

This interface is intended for base ECDH key establishment operations. Callers are responsible for providing correctly sized buffers and, where applicable, a cryptographically secure random generator callback.

Example:

uint8_t puba[QSC_ECDHP384_PUBLICKEY_SIZE];
uint8_t pria[QSC_ECDHP384_PRIVATEKEY_SIZE];
uint8_t pubb[QSC_ECDHP384_PUBLICKEY_SIZE];
uint8_t prib[QSC_ECDHP384_PRIVATEKEY_SIZE];
uint8_t seca[QSC_ECDHP384_SHAREDSECRET_SIZE];
uint8_t secb[QSC_ECDHP384_SHAREDSECRET_SIZE];
 
qsc_p384_generate_keypair(puba, pria, rng_generate);
qsc_p384_generate_keypair(pubb, prib, rng_generate);
 
if (qsc_p384_key_exchange(seca, pubb, pria) == true &&
    qsc_p384_key_exchange(secb, puba, prib) == true)
{
    // seca and secb should contain the same shared secret
}

Function Documentation

qsc_p384_generate_keypair()

QSC_EXPORT_API void qsc_p384_generate_keypair	(	uint8_t *	publickey,
		uint8_t *	privatekey,
		bool(*	rng_generate )(uint8_t *, size_t) )

Generate a random P-384 public and private key-pair.

Parameters

publickey	[uint8_t*] The output buffer that receives the serialized public key; must be at least QSC_ECDHP384_PUBLICKEY_SIZE bytes.
privatekey	[uint8_t*] The output buffer that receives the private key; must be at least QSC_ECDHP384_PRIVATEKEY_SIZE bytes.
rng_generate	[bool (*)(uint8_t*, size_t)] A pointer to a cryptographically secure random generator function that fills a buffer with random bytes and returns true on success.

Returns

[void] This function does not return a value.

qsc_p384_generate_seeded_keypair()

QSC_EXPORT_API void qsc_p384_generate_seeded_keypair	(	uint8_t *	publickey,
		uint8_t *	privatekey,
		const uint8_t *	seed )

Generate a deterministic P-384 public and private key-pair from a seed.

Parameters

publickey	[uint8_t*] The output buffer that receives the serialized public key; must be at least QSC_ECDHP384_PUBLICKEY_SIZE bytes.
privatekey	[uint8_t*] The output buffer that receives the private key; must be at least QSC_ECDHP384_PRIVATEKEY_SIZE bytes.
seed	[const uint8_t*] The input seed buffer; must contain QSC_ECDHP384_SEED_SIZE bytes.

Returns

[void] This function does not return a value.

qsc_p384_key_exchange()

QSC_EXPORT_API bool qsc_p384_key_exchange	(	uint8_t *	secret,
		const uint8_t *	publickey,
		const uint8_t *	privatekey )

Derive a P-384 shared secret using a peer public key and a local private key.

Parameters

secret	[uint8_t*] The output buffer that receives the shared secret; must be at least QSC_ECDHP384_SHAREDSECRET_SIZE bytes.
publickey	[const uint8_t*] The peer serialized public key; must contain QSC_ECDHP384_PUBLICKEY_SIZE bytes.
privatekey	[const uint8_t*] The local private key; must contain QSC_ECDHP384_PRIVATEKEY_SIZE bytes.

Returns

[bool] Returns true if the shared secret was generated successfully; returns false on failure.

qsc_p384_public_from_private()

QSC_EXPORT_API void qsc_p384_public_from_private	(	uint8_t *	publickey,
		const uint8_t *	privatekey )

Derive a serialized P-384 public key from a private key.

Parameters

publickey	[uint8_t*] The output buffer that receives the serialized public key; must be at least QSC_ECDHP384_PUBLICKEY_SIZE bytes.
privatekey	[const uint8_t*] The input private key buffer; must contain QSC_ECDHP384_PRIVATEKEY_SIZE bytes.

Returns

[void] This function does not return a value.