/*
   * Copyright (c) 2013, Google Inc.
   *
   * (C) Copyright 2008 Semihalf
   *
   * (C) Copyright 2000-2006
   * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   *

   * SPDX-License-Identifier:	GPL-2.0+

   */
  
  #ifndef _RSA_H
  #define _RSA_H
  
  #include <errno.h>
  #include <image.h>

  /**
   * struct rsa_public_key - holder for a public key
   *
   * An RSA public key consists of a modulus (typically called N), the inverse
   * and R^2, where R is 2^(# key bits).
   */
  
  struct rsa_public_key {
  	uint len;		/* len of modulus[] in number of uint32_t */
  	uint32_t n0inv;		/* -1 / modulus[0] mod 2^32 */
  	uint32_t *modulus;	/* modulus as little endian array */
  	uint32_t *rr;		/* R^2 as little endian array */

  	uint64_t exponent;	/* public exponent */

  };

  struct image_sign_info;

  #if IMAGE_ENABLE_SIGN
  /**
   * sign() - calculate and return signature for given input data
   *
   * @info:	Specifies key and FIT information
   * @data:	Pointer to the input data
   * @data_len:	Data length
   * @sigp:	Set to an allocated buffer holding the signature
   * @sig_len:	Set to length of the calculated hash
   *
   * This computes input data signature according to selected algorithm.
   * Resulting signature value is placed in an allocated buffer, the
   * pointer is returned as *sigp. The length of the calculated
   * signature is returned via the sig_len pointer argument. The caller
   * should free *sigp.
   *
   * @return: 0, on success, -ve on error
   */
  int rsa_sign(struct image_sign_info *info,
  	     const struct image_region region[],
  	     int region_count, uint8_t **sigp, uint *sig_len);
  
  /**
   * add_verify_data() - Add verification information to FDT
   *
   * Add public key information to the FDT node, suitable for
   * verification at run-time. The information added depends on the
   * algorithm being used.
   *
   * @info:	Specifies key and FIT information
   * @keydest:	Destination FDT blob for public key data

   * @return: 0, on success, -ENOSPC if the keydest FDT blob ran out of space,
  		other -ve value on error

  */
  int rsa_add_verify_data(struct image_sign_info *info, void *keydest);
  #else
  static inline int rsa_sign(struct image_sign_info *info,
  		const struct image_region region[], int region_count,
  		uint8_t **sigp, uint *sig_len)
  {
  	return -ENXIO;
  }
  
  static inline int rsa_add_verify_data(struct image_sign_info *info,
  				      void *keydest)
  {
  	return -ENXIO;
  }
  #endif
  
  #if IMAGE_ENABLE_VERIFY
  /**
   * rsa_verify() - Verify a signature against some data
   *
   * Verify a RSA PKCS1.5 signature against an expected hash.
   *
   * @info:	Specifies key and FIT information
   * @data:	Pointer to the input data
   * @data_len:	Data length
   * @sig:	Signature
   * @sig_len:	Number of bytes in signature
   * @return 0 if verified, -ve on error
   */
  int rsa_verify(struct image_sign_info *info,
  	       const struct image_region region[], int region_count,
  	       uint8_t *sig, uint sig_len);
  #else
  static inline int rsa_verify(struct image_sign_info *info,
  		const struct image_region region[], int region_count,
  		uint8_t *sig, uint sig_len)
  {
  	return -ENXIO;
  }
  #endif

  #define RSA2048_BYTES	(2048 / 8)
  #define RSA4096_BYTES	(4096 / 8)
  
  /* This is the minimum/maximum key size we support, in bits */
  #define RSA_MIN_KEY_BITS	2048
  #define RSA_MAX_KEY_BITS	4096
  
  /* This is the maximum signature length that we support, in bits */
  #define RSA_MAX_SIG_BITS	4096

  #endif