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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
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with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
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*/

/**
 * @file ecdh.h
 * @author Mike Scott and Kealan McCusker
 * @date 2nd June 2015
 * @brief ECDH Header file for implementation of standard EC protocols
 *
 * declares functions
 *
 */

#ifndef ECDH_H
#define ECDH_H

#include "amcl.h"

#define EAS 16 /**< Symmetric Key size - 128 bits */
#define EGS MODBYTES  /**< ECC Group Size in bytes */
#define EFS MODBYTES  /**< ECC Field Size in bytes */

#define HASH_TYPE_ECC SHA256  /**< Hash type */

#define ECDH_OK                     0     /**< Function completed without error */
/*#define ECDH_DOMAIN_ERROR          -1*/
#define ECDH_INVALID_PUBLIC_KEY    -2	/**< Public Key is Invalid */
#define ECDH_ERROR                 -3	/**< ECDH Internal Error */
#define ECDH_INVALID               -4	/**< ECDH Internal Error */
/*#define ECDH_DOMAIN_NOT_FOUND      -5
#define ECDH_OUT_OF_MEMORY         -6
#define ECDH_DIV_BY_ZERO           -7
#define ECDH_BAD_ASSUMPTION        -8*/

/* ECDH Auxiliary Functions */


/**	@brief hash an octet into another octet
 *
 	@param h is the hash type
	@param I input octet
	@param O output octet - H(I)
 */
extern void HASH(int h,octet *I,octet *O);
/**	@brief HMAC of message M using key K to create tag of length len in octet tag
 *
	IEEE-1363 MAC1 function. Uses SHA256 internally.
	@param h is the hash type
	@param M input message octet
	@param K input encryption key
	@param len is output desired length of HMAC tag
	@param tag is the output HMAC
	@return 0 for bad parameters, else 1
 */
extern int HMAC(int h,octet *M,octet *K,int len,octet *tag);

/*extern void KDF1(octet *,int,octet *);*/

/**	@brief Key Derivation Function - generates key K from inputs Z and P
 *
	IEEE-1363 KDF2 Key Derivation Function. Uses SHA256 internally.
	@param h is the hash type
	@param Z input octet
	@param P input key derivation parameters - can be NULL
	@param len is output desired length of key
	@param K is the derived key
 */
extern void KDF2(int h,octet *Z,octet *P,int len,octet *K);
/**	@brief Password Based Key Derivation Function - generates key K from password, salt and repeat counter
 *
	PBKDF2 Password Based Key Derivation Function. Uses SHA256 internally.
	@param h is the hash type
	@param P input password
	@param S input salt
	@param rep Number of times to be iterated.
	@param len is output desired length
	@param K is the derived key
 */
extern void PBKDF2(int h,octet *P,octet *S,int rep,int len,octet *K);
/**	@brief AES encrypts a plaintext to a ciphtertext
 *
	IEEE-1363 AES_CBC_IV0_ENCRYPT function. Encrypts in CBC mode with a zero IV, padding as necessary to create a full final block.
	@param K AES key
	@param P input plaintext octet
	@param C output ciphertext octet
 */
extern void AES_CBC_IV0_ENCRYPT(octet *K,octet *P,octet *C);
/**	@brief AES encrypts a plaintext to a ciphtertext
 *
	IEEE-1363 AES_CBC_IV0_DECRYPT function. Decrypts in CBC mode with a zero IV.
	@param K AES key
	@param C input ciphertext octet
	@param P output plaintext octet
	@return 0 if bad input, else 1
 */
extern int AES_CBC_IV0_DECRYPT(octet *K,octet *C,octet *P);

/* ECDH primitives - support functions */
/**	@brief Generate an ECC public/private key pair
 *
	@param R is a pointer to a cryptographically secure random number generator
	@param s the private key, an output internally randomly generated if R!=NULL, otherwise must be provided as an input
	@param W the output public key, which is s.G, where G is a fixed generator
	@return 0 or an error code
 */
extern int  ECP_KEY_PAIR_GENERATE(csprng *R,octet *s,octet *W);
/**	@brief Validate an ECC public key
 *
	@param f if = 0 just does some simple checks, else tests that W is of the correct order
	@param W the input public key to be validated
	@return 0 if public key is OK, or an error code
 */
extern int  ECP_PUBLIC_KEY_VALIDATE(int f,octet *W);

/* ECDH primitives */

/**	@brief Generate Diffie-Hellman shared key
 *
	IEEE-1363 Diffie-Hellman shared secret calculation
	@param s is the input private key,
	@param W the input public key of the other party
	@param K the output shared key, in fact the x-coordinate of s.W
	@return 0 or an error code
 */
extern int ECPSVDP_DH(octet *s,octet *W,octet *K);
/*extern int ECPSVDP_DHC(octet *,octet *,int,octet *);*/

/*#if CURVETYPE!=MONTGOMERY */
/* ECIES functions */
/*#if CURVETYPE!=MONTGOMERY */
/* ECIES functions */
/**	@brief ECIES Encryption
 *
	IEEE-1363 ECIES Encryption
	@param h is the hash type
	@param P1 input Key Derivation parameters
	@param P2 input Encoding parameters
	@param R is a pointer to a cryptographically secure random number generator
	@param W the input public key of the recieving party
	@param M is the plaintext message to be encrypted
	@param len the length of the HMAC tag
	@param V component of the output ciphertext
	@param C the output ciphertext
	@param T the output HMAC tag, part of the ciphertext
 */
extern void ECP_ECIES_ENCRYPT(int h,octet *P1,octet *P2,csprng *R,octet *W,octet *M,int len,octet *V,octet *C,octet *T);
/**	@brief ECIES Decryption
 *
	IEEE-1363 ECIES Decryption
	@param h is the hash type
	@param P1 input Key Derivation parameters
	@param P2 input Encoding parameters
	@param V component of the input ciphertext
	@param C the input ciphertext
	@param T the input HMAC tag, part of the ciphertext
	@param U the input private key for decryption
	@param M the output plaintext message
	@return 1 if successful, else 0
 */
extern int ECP_ECIES_DECRYPT(int h,octet *P1,octet *P2,octet *V,octet *C,octet *T,octet *U,octet *M);

/* ECDSA functions */
/**	@brief ECDSA Signature
 *
	IEEE-1363 ECDSA Signature
	@param h is the hash type
	@param R is a pointer to a cryptographically secure random number generator
        @param k Ephemeral key. This value is used when R=NULL
	@param s the input private signing key
	@param M the input message to be signed
	@param c component of the output signature
	@param d component of the output signature

 */
extern int ECPSP_DSA(int h,csprng *R,octet *k,octet *s,octet *M,octet *c,octet *d);
/**	@brief ECDSA Signature Verification
 *
	IEEE-1363 ECDSA Signature Verification
	@param h is the hash type
	@param W the input public key
	@param M the input message
	@param c component of the input signature
	@param d component of the input signature
	@return 0 or an error code
 */
extern int ECPVP_DSA(int h,octet *W,octet *M,octet *c,octet *d);
/*#endif*/

#endif