Diff: include/polarssl/ecp.h

Revision:

0:137634ff4186

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/polarssl/ecp.h	Thu Jun 11 03:27:03 2015 +0000
@@ -0,0 +1,665 @@
+/**
+ * \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://tls.mbed.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          0 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          0 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          0 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 successful (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 */
+