/* ecc_dh.h - TinyCrypt interface to EC-DSA implementation */

/*
    Copyright (c) 2014, Kenneth MacKay
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

 * * Redistributions of source code must retain the above copyright notice, this
     list of conditions and the following disclaimer.

 * * Redistributions in binary form must reproduce the above copyright notice,
     this list of conditions and the following disclaimer in the documentation
     and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

/*
    Copyright (C) 2017 by Intel Corporation, All Rights Reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

      - Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.

      - Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.

      - Neither the name of Intel Corporation nor the names of its contributors
      may be used to endorse or promote products derived from this software
      without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

/**
    @file
    @brief -- 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).
*/

#ifndef __TC_ECC_DSA_H__
#define __TC_ECC_DSA_H__

#include <tinycrypt/ecc.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
    @brief Generate an ECDSA signature for a given hash value.
    @return returns TC_CRYPTO_SUCCESS (1) if the signature generated successfully
           returns TC_CRYPTO_FAIL (0) if an error occurred.

    @param p_private_key IN -- Your private key.
    @param p_message_hash IN -- The hash of the message to sign.
    @param p_hash_size IN -- The size of p_message_hash in bytes.
    @param 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.
    @note side-channel countermeasure: algorithm strengthened against timing
    attack.
*/
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);

#ifdef ENABLE_TESTS
/*
    THIS FUNCTION SHOULD BE CALLED FOR TEST PURPOSES ONLY.
    Refer to uECC_sign() function for real applications.
*/
int uECC_sign_with_k(const uint8_t* private_key, const uint8_t* message_hash,
                     unsigned int hash_size, uECC_word_t* k, uint8_t* signature,
                     uECC_Curve curve);
#endif

/**
    @brief Verify an ECDSA signature.
    @return returns TC_SUCCESS (1) if the signature is valid
       returns TC_FAIL (0) if the signature is invalid.

    @param p_public_key IN -- The signer's public key.
    @param p_message_hash IN -- The hash of the signed data.
    @param p_hash_size IN -- The size of p_message_hash in bytes.
    @param 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).
*/
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);

#ifdef __cplusplus
}
#endif

#endif /* __TC_ECC_DSA_H__ */
