ecc_dh.h File Reference

– Interface to EC-DH implementation. More...

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Functions
int	uECC_make_key (uint8_t *p_public_key, uint8_t *p_private_key, uECC_Curve curve)
	Create a public/private key pair.
int	uECC_shared_secret (const uint8_t *p_public_key, const uint8_t *p_private_key, uint8_t *p_secret, uECC_Curve curve)
	Compute a shared secret given your secret key and someone else's public key.

Detailed Description

– Interface to EC-DH implementation.

Overview: This software is an implementation of EC-DH. This implementation uses curve NIST p-256.

Security: The curve NIST p-256 provides approximately 128 bits of security.

Function Documentation

uECC_make_key()

int uECC_make_key	(	uint8_t *	p_public_key,
		uint8_t *	p_private_key,
		uECC_Curve	curve
	)

Create a public/private key pair.

Returns

returns TC_CRYPTO_SUCCESS (1) if the key pair was generated successfully returns TC_CRYPTO_FAIL (0) if error while generating key pair

Parameters

p_public_key	OUT – Will be filled in with the public key. Must be at least 2 * the curve size (in bytes) long. For curve secp256r1, p_public_key must be 64 bytes long.
p_private_key	OUT – Will be filled in with the private key. Must be as long as the curve order (for secp256r1, p_private_key must be 32 bytes long).

Note

side-channel countermeasure: algorithm strengthened against timing attack.

Warning

A cryptographically-secure PRNG function must be set (using uECC_set_rng()) before calling uECC_make_key().

uECC_shared_secret()

int uECC_shared_secret	(	const uint8_t *	p_public_key,
		const uint8_t *	p_private_key,
		uint8_t *	p_secret,
		uECC_Curve	curve
	)

Compute a shared secret given your secret key and someone else's public key.

Returns

returns TC_CRYPTO_SUCCESS (1) if the shared secret was computed successfully returns TC_CRYPTO_FAIL (0) otherwise

Parameters

p_secret	OUT – Will be filled in with the shared secret value. Must be the same size as the curve size (for curve secp256r1, secret must be 32 bytes long.
p_public_key	IN – The public key of the remote party.
p_private_key	IN – Your private key.

Warning

It is recommended to use the output of uECC_shared_secret() as the input of a recommended Key Derivation Function (see NIST SP 800-108) in order to produce a cryptographically secure symmetric key.