text: /**
   * \file ecp.h
   *
   * \brief Elliptic curves over GF(p)
   *
   *  Copyright (C) 2006-2013, ARM Limited, All Rights Reserved
   *
   *  This file is part of mbed TLS (https://polarssl.org)
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; either version 2 of the License, or
   *  (at your option) any later version.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along
   *  with this program; if not, write to the Free Software Foundation, Inc.,
   *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   */
  #ifndef POLARSSL_ECP_H
  #define POLARSSL_ECP_H
  
  #include "bignum.h"
  
  /*
   * ECP error codes
   */
  #define POLARSSL_ERR_ECP_BAD_INPUT_DATA                    -0x4F80  /**< Bad input parameters to function. */
  #define POLARSSL_ERR_ECP_BUFFER_TOO_SMALL                  -0x4F00  /**< The buffer is too small to write to. */
  #define POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE               -0x4E80  /**< Requested curve not available. */
  #define POLARSSL_ERR_ECP_VERIFY_FAILED                     -0x4E00  /**< The signature is not valid. */
  #define POLARSSL_ERR_ECP_MALLOC_FAILED                     -0x4D80  /**< Memory allocation failed. */
  #define POLARSSL_ERR_ECP_RANDOM_FAILED                     -0x4D00  /**< Generation of random value, such as (ephemeral) key, failed. */
  #define POLARSSL_ERR_ECP_INVALID_KEY                       -0x4C80  /**< Invalid private or public key. */
  #define POLARSSL_ERR_ECP_SIG_LEN_MISMATCH                  -0x4C00  /**< Signature is valid but shorter than the user-supplied length. */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * Domain parameters (curve, subgroup and generator) identifiers.
   *
   * Only curves over prime fields are supported.
   *
   * \warning This library does not support validation of arbitrary domain
   * parameters. Therefore, only well-known domain parameters from trusted
   * sources should be used. See ecp_use_known_dp().
   */
  typedef enum
  {
      POLARSSL_ECP_DP_NONE = 0,
      POLARSSL_ECP_DP_SECP192R1,      /*!< 192-bits NIST curve  */
      POLARSSL_ECP_DP_SECP224R1,      /*!< 224-bits NIST curve  */
      POLARSSL_ECP_DP_SECP256R1,      /*!< 256-bits NIST curve  */
      POLARSSL_ECP_DP_SECP384R1,      /*!< 384-bits NIST curve  */
      POLARSSL_ECP_DP_SECP521R1,      /*!< 521-bits NIST curve  */
      POLARSSL_ECP_DP_BP256R1,        /*!< 256-bits Brainpool curve */
      POLARSSL_ECP_DP_BP384R1,        /*!< 384-bits Brainpool curve */
      POLARSSL_ECP_DP_BP512R1,        /*!< 512-bits Brainpool curve */
      POLARSSL_ECP_DP_M221,           /*!< (not implemented yet)    */
      POLARSSL_ECP_DP_M255,           /*!< Curve25519               */
      POLARSSL_ECP_DP_M383,           /*!< (not implemented yet)    */
      POLARSSL_ECP_DP_M511,           /*!< (not implemented yet)    */
      POLARSSL_ECP_DP_SECP192K1,      /*!< 192-bits "Koblitz" curve */
      POLARSSL_ECP_DP_SECP224K1,      /*!< 224-bits "Koblitz" curve */
      POLARSSL_ECP_DP_SECP256K1,      /*!< 256-bits "Koblitz" curve */
  } ecp_group_id;
  
  /**
   * Number of supported curves (plus one for NONE).
   *
   * (Montgomery curves excluded for now.)
   */
  #define POLARSSL_ECP_DP_MAX     12
  
  /**
   * Curve information for use by other modules
   */
  typedef struct
  {
      ecp_group_id grp_id;    /*!< Internal identifier        */
      uint16_t tls_id;        /*!< TLS NamedCurve identifier  */
      uint16_t size;          /*!< Curve size in bits         */
      const char *name;       /*!< Human-friendly name        */
  } ecp_curve_info;
  
  /**
   * \brief           ECP point structure (jacobian coordinates)
   *
   * \note            All functions expect and return points satisfying
   *                  the following condition: Z == 0 or Z == 1. (Other
   *                  values of Z are used by internal functions only.)
   *                  The point is zero, or "at infinity", if Z == 0.
   *                  Otherwise, X and Y are its standard (affine) coordinates.
   */
  typedef struct
  {
      mpi X;          /*!<  the point's X coordinate  */
      mpi Y;          /*!<  the point's Y coordinate  */
      mpi Z;          /*!<  the point's Z coordinate  */
  }
  ecp_point;
  
  /**
   * \brief           ECP group structure
   *
   * We consider two types of curves equations:
   * 1. Short Weierstrass y^2 = x^3 + A x + B     mod P   (SEC1 + RFC 4492)
   * 2. Montgomery,       y^2 = x^3 + A x^2 + x   mod P   (M255 + draft)
   * In both cases, a generator G for a prime-order subgroup is fixed. In the
   * short weierstrass, this subgroup is actually the whole curve, and its
   * cardinal is denoted by N.
   *
   * In the case of Short Weierstrass curves, our code requires that N is an odd
   * prime. (Use odd in ecp_mul() and prime in ecdsa_sign() for blinding.)
   *
   * In the case of Montgomery curves, we don't store A but (A + 2) / 4 which is
   * the quantity actually used in the formulas. Also, nbits is not the size of N
   * but the required size for private keys.
   *
   * If modp is NULL, reduction modulo P is done using a generic algorithm.
   * Otherwise, it must point to a function that takes an mpi in the range
   * 0..2^(2*pbits)-1 and transforms it in-place in an integer of little more
   * than pbits, so that the integer may be efficiently brought in the 0..P-1
   * range by a few additions or substractions. It must return 0 on success and
   * non-zero on failure.
   */
  typedef struct
  {
      ecp_group_id id;    /*!<  internal group identifier                     */
      mpi P;              /*!<  prime modulus of the base field               */
      mpi A;              /*!<  1. A in the equation, or 2. (A + 2) / 4       */
      mpi B;              /*!<  1. B in the equation, or 2. unused            */
      ecp_point G;        /*!<  generator of the (sub)group used              */
      mpi N;              /*!<  1. the order of G, or 2. unused               */
      size_t pbits;       /*!<  number of bits in P                           */
      size_t nbits;       /*!<  number of bits in 1. P, or 2. private keys    */
      unsigned int h;     /*!<  internal: 1 if the constants are static       */
      int (*modp)(mpi *); /*!<  function for fast reduction mod P             */
      int (*t_pre)(ecp_point *, void *);  /*!< unused                         */
      int (*t_post)(ecp_point *, void *); /*!< unused                         */
      void *t_data;                       /*!< unused                         */
      ecp_point *T;       /*!<  pre-computed points for ecp_mul_comb()        */
      size_t T_size;      /*!<  number for pre-computed points                */
  }
  ecp_group;
  
  /**
   * \brief           ECP key pair structure
   *
   * A generic key pair that could be used for ECDSA, fixed ECDH, etc.
   *
   * \note Members purposefully in the same order as struc ecdsa_context.
   */
  typedef struct
  {
      ecp_group grp;      /*!<  Elliptic curve and base point     */
      mpi d;              /*!<  our secret value                  */
      ecp_point Q;        /*!<  our public value                  */
  }
  ecp_keypair;
  
  /**
   * \name SECTION: Module settings
   *
   * The configuration options you can set for this module are in this section.
   * Either change them in config.h or define them on the compiler command line.
   * \{
   */
  
  #if !defined(POLARSSL_ECP_MAX_BITS)
  /**
   * Maximum size of the groups (that is, of N and P)
   */
  #define POLARSSL_ECP_MAX_BITS     521   /**< Maximum bit size of groups */
  #endif
  
  #define POLARSSL_ECP_MAX_BYTES    ( ( POLARSSL_ECP_MAX_BITS + 7 ) / 8 )
  #define POLARSSL_ECP_MAX_PT_LEN   ( 2 * POLARSSL_ECP_MAX_BYTES + 1 )
  
  #if !defined(POLARSSL_ECP_WINDOW_SIZE)
  /*
   * Maximum "window" size used for point multiplication.
   * Default: 6.
   * Minimum value: 2. Maximum value: 7.
   *
   * Result is an array of at most ( 1 << ( POLARSSL_ECP_WINDOW_SIZE - 1 ) )
   * points used for point multiplication. This value is directly tied to EC
   * peak memory usage, so decreasing it by one should roughly cut memory usage
   * by two (if large curves are in use).
   *
   * Reduction in size may reduce speed, but larger curves are impacted first.
   * Sample performances (in ECDHE handshakes/s, with FIXED_POINT_OPTIM = 1):
   *      w-size:     6       5       4       3       2
   *      521       145     141     135     120      97
   *      384       214     209     198     177     146
   *      256       320     320     303     262     226
  
   *      224       475     475     453     398     342
   *      192       640     640     633     587     476
   */
  #define POLARSSL_ECP_WINDOW_SIZE    6   /**< Maximum window size used */
  #endif /* POLARSSL_ECP_WINDOW_SIZE */
  
  #if !defined(POLARSSL_ECP_FIXED_POINT_OPTIM)
  /*
   * Trade memory for speed on fixed-point multiplication.
   *
   * This speeds up repeated multiplication of the generator (that is, the
   * multiplication in ECDSA signatures, and half of the multiplications in
   * ECDSA verification and ECDHE) by a factor roughly 3 to 4.
   *
   * The cost is increasing EC peak memory usage by a factor roughly 2.
   *
   * Change this value to 0 to reduce peak memory usage.
   */
  #define POLARSSL_ECP_FIXED_POINT_OPTIM  1   /**< Enable fixed-point speed-up */
  #endif /* POLARSSL_ECP_FIXED_POINT_OPTIM */
  
  /* \} name SECTION: Module settings */
  
  /*
   * Point formats, from RFC 4492's enum ECPointFormat
   */
  #define POLARSSL_ECP_PF_UNCOMPRESSED    0   /**< Uncompressed point format */
  #define POLARSSL_ECP_PF_COMPRESSED      1   /**< Compressed point format */
  
  /*
   * Some other constants from RFC 4492
   */
  #define POLARSSL_ECP_TLS_NAMED_CURVE    3   /**< ECCurveType's named_curve */
  
  /**
   * \brief           Get the list of supported curves in order of preferrence
   *                  (full information)
   *
   * \return          A statically allocated array, the last entry is 0.
   */
  const ecp_curve_info *ecp_curve_list( void );
  
  /**
   * \brief           Get the list of supported curves in order of preferrence
   *                  (grp_id only)
   *
   * \return          A statically allocated array,
   *                  terminated with POLARSSL_ECP_DP_NONE.
   */
  const ecp_group_id *ecp_grp_id_list( void );
  
  /**
   * \brief           Get curve information from an internal group identifier
   *
   * \param grp_id    A POLARSSL_ECP_DP_XXX value
   *
   * \return          The associated curve information or NULL
   */
  const ecp_curve_info *ecp_curve_info_from_grp_id( ecp_group_id grp_id );
  
  /**
   * \brief           Get curve information from a TLS NamedCurve value
   *
   * \param tls_id    A POLARSSL_ECP_DP_XXX value
   *
   * \return          The associated curve information or NULL
   */
  const ecp_curve_info *ecp_curve_info_from_tls_id( uint16_t tls_id );
  
  /**
   * \brief           Get curve information from a human-readable name
   *
   * \param name      The name
   *
   * \return          The associated curve information or NULL
   */
  const ecp_curve_info *ecp_curve_info_from_name( const char *name );
  
  /**
   * \brief           Initialize a point (as zero)
   */
  void ecp_point_init( ecp_point *pt );
  
  /**
   * \brief           Initialize a group (to something meaningless)
   */
  void ecp_group_init( ecp_group *grp );
  
  /**
   * \brief           Initialize a key pair (as an invalid one)
   */
  void ecp_keypair_init( ecp_keypair *key );
  
  /**
   * \brief           Free the components of a point
   */
  void ecp_point_free( ecp_point *pt );
  
  /**
   * \brief           Free the components of an ECP group
   */
  void ecp_group_free( ecp_group *grp );
  
  /**
   * \brief           Free the components of a key pair
   */
  void ecp_keypair_free( ecp_keypair *key );
  
  /**
   * \brief           Copy the contents of point Q into P
   *
   * \param P         Destination point
   * \param Q         Source point
   *
   * \return          0 if successful,
   *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
   */
  int ecp_copy( ecp_point *P, const ecp_point *Q );
  
  /**
   * \brief           Copy the contents of a group object
   *
   * \param dst       Destination group
   * \param src       Source group
   *
   * \return          0 if successful,
   *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
   */
  int ecp_group_copy( ecp_group *dst, const ecp_group *src );
  
  /**
   * \brief           Set a point to zero
   *
   * \param pt        Destination point
   *
   * \return          0 if successful,
   *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
   */
  int ecp_set_zero( ecp_point *pt );
  
  /**
   * \brief           Tell if a point is zero
   *
   * \param pt        Point to test
   *
   * \return          1 if point is zero, 0 otherwise
   */
  int ecp_is_zero( ecp_point *pt );
  
  /**
   * \brief           Import a non-zero point from two ASCII strings
   *
   * \param P         Destination point
   * \param radix     Input numeric base
   * \param x         First affine coordinate as a null-terminated string
   * \param y         Second affine coordinate as a null-terminated string
   *
   * \return          0 if successful, or a POLARSSL_ERR_MPI_XXX error code
   */
  int ecp_point_read_string( ecp_point *P, int radix,
                             const char *x, const char *y );
  
  /**
   * \brief           Export a point into unsigned binary data
   *
   * \param grp       Group to which the point should belong
   * \param P         Point to export
   * \param format    Point format, should be a POLARSSL_ECP_PF_XXX macro
   * \param olen      Length of the actual output
   * \param buf       Output buffer
   * \param buflen    Length of the output buffer
   *
   * \return          0 if successful,
   *                  or POLARSSL_ERR_ECP_BAD_INPUT_DATA
   *                  or POLARSSL_ERR_ECP_BUFFER_TOO_SMALL
   */
  int ecp_point_write_binary( const ecp_group *grp, const ecp_point *P,
                              int format, size_t *olen,
                              unsigned char *buf, size_t buflen );
  
  /**
   * \brief           Import a point from unsigned binary data
   *
   * \param grp       Group to which the point should belong
   * \param P         Point to import
   * \param buf       Input buffer
   * \param ilen      Actual length of input
   *
   * \return          0 if successful,
   *                  POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid,
   *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed,
   *                  POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE if the point format
   *                  is not implemented.
   *
   * \note            This function does NOT check that the point actually
   *                  belongs to the given group, see ecp_check_pubkey() for
   *                  that.
   */
  int ecp_point_read_binary( const ecp_group *grp, ecp_point *P,
                             const unsigned char *buf, size_t ilen );
  
  /**
   * \brief           Import a point from a TLS ECPoint record
   *
   * \param grp       ECP group used
   * \param pt        Destination point
   * \param buf       $(Start of input buffer)
   * \param len       Buffer length
   *
   * \note            buf is updated to point right after the ECPoint on exit
   *
   * \return          O if successful,
   *                  POLARSSL_ERR_MPI_XXX if initialization failed
   *                  POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid
   */
  int ecp_tls_read_point( const ecp_group *grp, ecp_point *pt,
                          const unsigned char **buf, size_t len );
  
  /**
   * \brief           Export a point as a TLS ECPoint record
   *
   * \param grp       ECP group used
   * \param pt        Point to export
   * \param format    Export format
   * \param olen      length of data written
   * \param buf       Buffer to write to
   * \param blen      Buffer length
   *
   * \return          0 if successful,
   *                  or POLARSSL_ERR_ECP_BAD_INPUT_DATA
   *                  or POLARSSL_ERR_ECP_BUFFER_TOO_SMALL
   */
  int ecp_tls_write_point( const ecp_group *grp, const ecp_point *pt,
                           int format, size_t *olen,
                           unsigned char *buf, size_t blen );
  
  /**
   * \brief           Import an ECP group from null-terminated ASCII strings
   *
   * \param grp       Destination group
   * \param radix     Input numeric base
   * \param p         Prime modulus of the base field
   * \param b         Constant term in the equation
   * \param gx        The generator's X coordinate
   * \param gy        The generator's Y coordinate
   * \param n         The generator's order
   *
   * \return          0 if successful, or a POLARSSL_ERR_MPI_XXX error code
   *
   * \note            Sets all fields except modp.
   */
  int ecp_group_read_string( ecp_group *grp, int radix,
                             const char *p, const char *b,
                             const char *gx, const char *gy, const char *n);
  
  /**
   * \brief           Set a group using well-known domain parameters
   *
   * \param grp       Destination group
   * \param index     Index in the list of well-known domain parameters
   *
   * \return          O if successful,
   *                  POLARSSL_ERR_MPI_XXX if initialization failed
   *                  POLARSSL_ERR_ECP_FEATURE_UNAVAILABLE for unkownn groups
   *
   * \note            Index should be a value of RFC 4492's enum NamdeCurve,
   *                  possibly in the form of a POLARSSL_ECP_DP_XXX macro.
   */
  int ecp_use_known_dp( ecp_group *grp, ecp_group_id index );
  
  /**
   * \brief           Set a group from a TLS ECParameters record
   *
   * \param grp       Destination group
   * \param buf       &(Start of input buffer)
   * \param len       Buffer length
   *
   * \note            buf is updated to point right after ECParameters on exit
   *
   * \return          O if successful,
   *                  POLARSSL_ERR_MPI_XXX if initialization failed
   *                  POLARSSL_ERR_ECP_BAD_INPUT_DATA if input is invalid
   */
  int ecp_tls_read_group( ecp_group *grp, const unsigned char **buf, size_t len );
  
  /**
   * \brief           Write the TLS ECParameters record for a group
   *
   * \param grp       ECP group used
   * \param olen      Number of bytes actually written
   * \param buf       Buffer to write to
   * \param blen      Buffer length
   *
   * \return          0 if successful,
   *                  or POLARSSL_ERR_ECP_BUFFER_TOO_SMALL
   */
  int ecp_tls_write_group( const ecp_group *grp, size_t *olen,
                           unsigned char *buf, size_t blen );
  
  /**
   * \brief           Addition: R = P + Q
   *
   * \param grp       ECP group
   * \param R         Destination point
   * \param P         Left-hand point
   * \param Q         Right-hand point
   *
   * \return          0 if successful,
   *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
   *
   * \note            This function does not support Montgomery curves, such as
   *                  Curve25519.
   */
  int ecp_add( const ecp_group *grp, ecp_point *R,
               const ecp_point *P, const ecp_point *Q );
  
  /**
   * \brief           Subtraction: R = P - Q
   *
   * \param grp       ECP group
   * \param R         Destination point
   * \param P         Left-hand point
   * \param Q         Right-hand point
   *
   * \return          0 if successful,
   *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
   *
   * \note            This function does not support Montgomery curves, such as
   *                  Curve25519.
   */
  int ecp_sub( const ecp_group *grp, ecp_point *R,
               const ecp_point *P, const ecp_point *Q );
  
  /**
   * \brief           Multiplication by an integer: R = m * P
   *                  (Not thread-safe to use same group in multiple threads)
   *
   * \param grp       ECP group
   * \param R         Destination point
   * \param m         Integer by which to multiply
   * \param P         Point to multiply
   * \param f_rng     RNG function (see notes)
   * \param p_rng     RNG parameter
   *
   * \return          0 if successful,
   *                  POLARSSL_ERR_ECP_INVALID_KEY if m is not a valid privkey
   *                  or P is not a valid pubkey,
   *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
   *
   * \note            In order to prevent timing attacks, this function
   *                  executes the exact same sequence of (base field)
   *                  operations for any valid m. It avoids any if-branch or
   *                  array index depending on the value of m.
   *
   * \note            If f_rng is not NULL, it is used to randomize intermediate
   *                  results in order to prevent potential timing attacks
   *                  targeting these results. It is recommended to always
   *                  provide a non-NULL f_rng (the overhead is negligible).
   */
  int ecp_mul( ecp_group *grp, ecp_point *R,
               const mpi *m, const ecp_point *P,
               int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
  
  /**
   * \brief           Check that a point is a valid public key on this curve
   *
   * \param grp       Curve/group the point should belong to
   * \param pt        Point to check
   *
   * \return          0 if point is a valid public key,
   *                  POLARSSL_ERR_ECP_INVALID_KEY otherwise.
   *
   * \note            This function only checks the point is non-zero, has valid
   *                  coordinates and lies on the curve, but not that it is
   *                  indeed a multiple of G. This is additional check is more
   *                  expensive, isn't required by standards, and shouldn't be
   *                  necessary if the group used has a small cofactor. In
   *                  particular, it is useless for the NIST groups which all
   *                  have a cofactor of 1.
   *
   * \note            Uses bare components rather than an ecp_keypair structure
   *                  in order to ease use with other structures such as
   *                  ecdh_context of ecdsa_context.
   */
  int ecp_check_pubkey( const ecp_group *grp, const ecp_point *pt );
  
  /**
   * \brief           Check that an mpi is a valid private key for this curve
   *
   * \param grp       Group used
   * \param d         Integer to check
   *
   * \return          0 if point is a valid private key,
   *                  POLARSSL_ERR_ECP_INVALID_KEY otherwise.
   *
   * \note            Uses bare components rather than an ecp_keypair structure
   *                  in order to ease use with other structures such as
   *                  ecdh_context of ecdsa_context.
   */
  int ecp_check_privkey( const ecp_group *grp, const mpi *d );
  
  /**
   * \brief           Generate a keypair
   *
   * \param grp       ECP group
   * \param d         Destination MPI (secret part)
   * \param Q         Destination point (public part)
   * \param f_rng     RNG function
   * \param p_rng     RNG parameter
   *
   * \return          0 if successful,
   *                  or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
   *
   * \note            Uses bare components rather than an ecp_keypair structure
   *                  in order to ease use with other structures such as
   *                  ecdh_context of ecdsa_context.
   */
  int ecp_gen_keypair( ecp_group *grp, mpi *d, ecp_point *Q,
                       int (*f_rng)(void *, unsigned char *, size_t),
                       void *p_rng );
  
  /**
   * \brief           Generate a keypair
   *
   * \param grp_id    ECP group identifier
   * \param key       Destination keypair
   * \param f_rng     RNG function
   * \param p_rng     RNG parameter
   *
   * \return          0 if successful,
   *                  or a POLARSSL_ERR_ECP_XXX or POLARSSL_MPI_XXX error code
   */
  int ecp_gen_key( ecp_group_id grp_id, ecp_keypair *key,
                  int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
  
  /**
   * \brief           Check a public-private key pair
   *
   * \param pub       Keypair structure holding a public key
   * \param prv       Keypair structure holding a private (plus public) key
   *
   * \return          0 if successfull (keys are valid and match), or
   *                  POLARSSL_ERR_ECP_BAD_INPUT_DATA, or
   *                  a POLARSSL_ERR_ECP_XXX or POLARSSL_ERR_MPI_XXX code.
   */
  int ecp_check_pub_priv( const ecp_keypair *pub, const ecp_keypair *prv );
  
  #if defined(POLARSSL_SELF_TEST)
  /**
   * \brief          Checkup routine
   *
   * \return         0 if successful, or 1 if a test failed
   */
  int ecp_self_test( int verbose );
  #endif
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* ecp.h */
  