text: /*
   * Copyright (c) 2018-2021, [Ribose Inc](https://www.ribose.com).
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. 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 HOLDERS 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.
   */
  
  #ifndef RNP_SIGNATURES_H_
  #define RNP_SIGNATURES_H_
  
  #include "types.h"
  #include "crypto/hash.h"
  
  /**
   * @brief Initialize a signature computation.
   * @param key the key that will be used to sign or verify
   * @param hash_alg the digest algo to be used
   * @param hash digest object that will be initialized
   */
  void signature_init(const pgp_key_material_t &key, pgp_hash_alg_t hash_alg, rnp::Hash &hash);
  
  /**
   * @brief Calculate signature with pre-populated hash
   * @param sig signature to calculate
   * @param seckey signing secret key material
   * @param hash pre-populated with signed data hash context. It is finalized and destroyed
   *             during the execution. Signature fields and trailer are hashed in this function.
   * @param rng random number generator
   */
  void signature_calculate(pgp_signature_t &         sig,
                           const pgp_key_material_t &seckey,
                           rnp::Hash &               hash,
                           rng_t &                   rng);
  
  /**
   * @brief Validate a signature with pre-populated hash. This method just checks correspondence
   *        between the hash and signature material. Expiration time and other fields are not
   *        checked for validity.
   * @param sig signature to validate
   * @param key public key material of the verifying key
   * @param hash pre-populated with signed data hash context. It is finalized
   *             during the execution. Signature fields and trailer are hashed in this function.
   * @return RNP_SUCCESS if signature was successfully validated or error code otherwise.
   */
  rnp_result_t signature_validate(const pgp_signature_t &   sig,
                                  const pgp_key_material_t &key,
                                  rnp::Hash &               hash);
  
  #endif
  