ecc_dsa.h File Reference

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

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Functions
int	uECC_sign (const uint8_t *p_private_key, const uint8_t *p_message_hash, unsigned p_hash_size, uint8_t *p_signature, uECC_Curve curve)
	Generate an ECDSA signature for a given hash value.
int	uECC_verify (const uint8_t *p_public_key, const uint8_t *p_message_hash, unsigned int p_hash_size, const uint8_t *p_signature, uECC_Curve curve)
	Verify an ECDSA signature.

Detailed Description

– Interface to EC-DSA implementation.

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

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

Usage: - To sign: Compute a hash of the data you wish to sign (SHA-2 is recommended) and pass it in to ecdsa_sign function along with your private key and a random number. You must use a new non-predictable random number to generate each new signature.

• To verify a signature: Compute the hash of the signed data using the same hash as the signer and pass it to this function along with the signer's public key and the signature values (r and s).

Function Documentation

uECC_sign()

int uECC_sign	(	const uint8_t *	p_private_key,
		const uint8_t *	p_message_hash,
		unsigned	p_hash_size,
		uint8_t *	p_signature,
		uECC_Curve	curve
	)

Generate an ECDSA signature for a given hash value.

Returns

returns TC_CRYPTO_SUCCESS (1) if the signature generated successfully returns TC_CRYPTO_FAIL (0) if an error occurred.

Parameters

p_private_key	IN – Your private key.
p_message_hash	IN – The hash of the message to sign.
p_hash_size	IN – The size of p_message_hash in bytes.
p_signature	OUT – Will be filled in with the signature value. Must be at least 2 * curve size long (for secp256r1, signature must be 64 bytes long).

Warning

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

Note

Usage: Compute a hash of the data you wish to sign (SHA-2 is recommended) and pass it in to this function along with your private key.

side-channel countermeasure: algorithm strengthened against timing attack.

uECC_verify()

int uECC_verify	(	const uint8_t *	p_public_key,
		const uint8_t *	p_message_hash,
		unsigned int	p_hash_size,
		const uint8_t *	p_signature,
		uECC_Curve	curve
	)

Verify an ECDSA signature.

Returns

returns TC_SUCCESS (1) if the signature is valid returns TC_FAIL (0) if the signature is invalid.

Parameters

p_public_key	IN – The signer's public key.
p_message_hash	IN – The hash of the signed data.
p_hash_size	IN – The size of p_message_hash in bytes.
p_signature	IN – The signature values.

Note

Usage: Compute the hash of the signed data using the same hash as the signer and pass it to this function along with the signer's public key and the signature values (hash_size and signature).