/*
   * Copyright (c) 2014, Ruchika Gupta.
   *
   * SPDX-License-Identifier:    GPL-2.0+
  */
  
  #ifndef _RSA_MOD_EXP_H
  #define _RSA_MOD_EXP_H
  
  #include <errno.h>
  #include <image.h>
  
  /**
   * struct key_prop - holder for a public key properties
   *
   * The struct has pointers to modulus (Typically called N),
   * The inverse, R^2, exponent. These can be typecasted and
   * used as byte arrays or converted to the required format
   * as per requirement of RSA implementation.
   */
  struct key_prop {
  	const void *rr;		/* R^2 can be treated as byte array */
  	const void *modulus;	/* modulus as byte array */
  	const void *public_exponent; /* public exponent as byte array */
  	uint32_t n0inv;		/* -1 / modulus[0] mod 2^32 */
  	int num_bits;		/* Key length in bits */
  	uint32_t exp_len;	/* Exponent length in number of uint8_t */
  };
  
  /**
   * rsa_mod_exp_sw() - Perform RSA Modular Exponentiation in sw
   *
   * Operation: out[] = sig ^ exponent % modulus
   *
   * @sig:	RSA PKCS1.5 signature
   * @sig_len:	Length of signature in number of bytes
   * @node:	Node with RSA key elements like modulus, exponent, R^2, n0inv
   * @out:	Result in form of byte array of len equal to sig_len
   */
  int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
  		struct key_prop *node, uint8_t *out);
  
  int rsa_mod_exp(struct udevice *dev, const uint8_t *sig, uint32_t sig_len,
  		struct key_prop *node, uint8_t *out);
  
  /**
   * struct struct mod_exp_ops - Driver model for RSA Modular Exponentiation
   *				operations
   *
   * The uclass interface is implemented by all crypto devices which use
   * driver model.
   */
  struct mod_exp_ops {
  	/**
  	 * Perform Modular Exponentiation
  	 *
  	 * Operation: out[] = sig ^ exponent % modulus
  	 *
  	 * @dev:	RSA Device
  	 * @sig:	RSA PKCS1.5 signature
  	 * @sig_len:	Length of signature in number of bytes
  	 * @node:	Node with RSA key elements like modulus, exponent,
  	 *		R^2, n0inv
  	 * @out:	Result in form of byte array of len equal to sig_len
  	 *
  	 * This function computes exponentiation over the signature.
  	 * Returns: 0 if exponentiation is successful, or a negative value
  	 * if it wasn't.
  	 */
  	int (*mod_exp)(struct udevice *dev, const uint8_t *sig,
  			   uint32_t sig_len, struct key_prop *node,
  			   uint8_t *outp);
  };
  
  #endif