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EC_GROUP_new(3)                     OpenSSL                    EC_GROUP_new(3)

       EC_GROUP_get_ecparameters, EC_GROUP_get_ecpkparameters,
       EC_GROUP_new_from_params, EC_GROUP_new_from_ecparameters,
       EC_GROUP_new_from_ecpkparameters, EC_GROUP_new, EC_GROUP_free,
       EC_GROUP_clear_free, EC_GROUP_new_curve_GFp, EC_GROUP_new_curve_GF2m,
       EC_GROUP_new_by_curve_name_ex, EC_GROUP_new_by_curve_name,
       EC_GROUP_set_curve, EC_GROUP_get_curve, EC_GROUP_set_curve_GFp,
       EC_GROUP_get_curve_GFp, EC_GROUP_set_curve_GF2m,
       EC_GROUP_get_curve_GF2m, EC_get_builtin_curves, OSSL_EC_curve_nid2name
       - Functions for creating and destroying EC_GROUP objects

       libcrypto, -lcrypto

        #include <openssl/ec.h>

        EC_GROUP *EC_GROUP_new_from_params(const OSSL_PARAM params[],
                                           OSSL_LIB_CTX *libctx, const char *propq);
        EC_GROUP *EC_GROUP_new_from_ecparameters(const ECPARAMETERS *params);
        EC_GROUP *EC_GROUP_new_from_ecpkparameters(const ECPKPARAMETERS *params);
        void EC_GROUP_free(EC_GROUP *group);

        EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,
                                         const BIGNUM *b, BN_CTX *ctx);
        EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,
                                          const BIGNUM *b, BN_CTX *ctx);
        EC_GROUP *EC_GROUP_new_by_curve_name_ex(OSSL_LIB_CTX *libctx, const char *propq,
                                                int nid);
        EC_GROUP *EC_GROUP_new_by_curve_name(int nid);

        int EC_GROUP_set_curve(EC_GROUP *group, const BIGNUM *p, const BIGNUM *a,
                               const BIGNUM *b, BN_CTX *ctx);
        int EC_GROUP_get_curve(const EC_GROUP *group, BIGNUM *p, BIGNUM *a, BIGNUM *b,
                               BN_CTX *ctx);

        ECPARAMETERS *EC_GROUP_get_ecparameters(const EC_GROUP *group,
                                                ECPARAMETERS *params);
        ECPKPARAMETERS *EC_GROUP_get_ecpkparameters(const EC_GROUP *group,
                                                    ECPKPARAMETERS *params);

        size_t EC_get_builtin_curves(EC_builtin_curve *r, size_t nitems);
        const char *OSSL_EC_curve_nid2name(int nid);

       The following functions have been deprecated since OpenSSL 3.0, and can
       be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
       version value, see openssl_user_macros(7):

        EC_GROUP *EC_GROUP_new(const EC_METHOD *meth);
        void EC_GROUP_clear_free(EC_GROUP *group);

        int EC_GROUP_set_curve_GFp(EC_GROUP *group, const BIGNUM *p,
                                   const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
        int EC_GROUP_get_curve_GFp(const EC_GROUP *group, BIGNUM *p,
                                   BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
        int EC_GROUP_set_curve_GF2m(EC_GROUP *group, const BIGNUM *p,
                                    const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
        int EC_GROUP_get_curve_GF2m(const EC_GROUP *group, BIGNUM *p,
                                    BIGNUM *a, BIGNUM *b, BN_CTX *ctx);

       Within the library there are two forms of elliptic curve that are of
       interest.  The first form is those defined over the prime field Fp. The
       elements of Fp are the integers 0 to p-1, where p is a prime number.
       This gives us a revised elliptic curve equation as follows:

       y^2 mod p = x^3 +ax + b mod p

       The second form is those defined over a binary field F2^m where the
       elements of the field are integers of length at most m bits. For this
       form the elliptic curve equation is modified to:

       y^2 + xy = x^3 + ax^2 + b (where b != 0)

       Operations in a binary field are performed relative to an irreducible
       polynomial. All such curves with OpenSSL use a trinomial or a
       pentanomial for this parameter.

       Although deprecated since OpenSSL 3.0 and should no longer be used, a
       new curve can be constructed by calling EC_GROUP_new(), using the
       implementation provided by meth (see EC_GFp_simple_method(3)) and
       associated with the library context ctx (see OSSL_LIB_CTX(3)).  The ctx
       parameter may be NULL in which case the default library context is
       used.  It is then necessary to call EC_GROUP_set_curve() to set the
       curve parameters.  Applications should instead use one of the other
       EC_GROUP_new_* constructors.

       EC_GROUP_new_from_params() creates a group with parameters specified by
       params.  The library context libctx (see OSSL_LIB_CTX(3)) and property
       query string propq are used to fetch algorithms from providers.  params
       may be either a list of explicit params or a named group, The values
       for ctx and propq may be NULL. The params that can be used are
       described in EVP_PKEY-EC(7).

       EC_GROUP_new_from_ecparameters() will create a group from the specified
       params and EC_GROUP_new_from_ecpkparameters() will create a group from
       the specific PK params.

       EC_GROUP_set_curve() sets the curve parameters p, a and b. For a curve
       over Fp p is the prime for the field. For a curve over F2^m p
       represents the irreducible polynomial - each bit represents a term in
       the polynomial.  Therefore, there will either be three or five bits set
       dependent on whether the polynomial is a trinomial or a pentanomial.
       In either case, a and b represents the coefficients a and b from the
       relevant equation introduced above.

       EC_group_get_curve() obtains the previously set curve parameters.

       EC_GROUP_set_curve_GFp() and EC_GROUP_set_curve_GF2m() are synonyms for
       EC_GROUP_set_curve(). They are defined for backwards compatibility only
       and should not be used.

       EC_GROUP_get_curve_GFp() and EC_GROUP_get_curve_GF2m() are synonyms for
       EC_GROUP_get_curve(). They are defined for backwards compatibility only
       and should not be used.

       The functions EC_GROUP_new_curve_GFp() and EC_GROUP_new_curve_GF2m()
       are shortcuts for calling EC_GROUP_new() and then the
       EC_GROUP_set_curve() function.  An appropriate default implementation
       method will be used.

       Whilst the library can be used to create any curve using the functions
       described above, there are also a number of predefined curves that are
       available. In order to obtain a list of all of the predefined curves,
       call the function EC_get_builtin_curves(). The parameter r should be an
       array of EC_builtin_curve structures of size nitems. The function will
       populate the r array with information about the built-in curves. If
       nitems is less than the total number of curves available, then the
       first nitems curves will be returned. Otherwise the total number of
       curves will be provided. The return value is the total number of curves
       available (whether that number has been populated in r or not). Passing
       a NULL r, or setting nitems to 0 will do nothing other than return the
       total number of curves available.  The EC_builtin_curve structure is
       defined as follows:

        typedef struct {
               int nid;
               const char *comment;
               } EC_builtin_curve;

       Each EC_builtin_curve item has a unique integer id (nid), and a human
       readable comment string describing the curve.

       In order to construct a built-in curve use the function
       EC_GROUP_new_by_curve_name_ex() and provide the nid of the curve to be
       constructed, the associated library context to be used in ctx (see
       OSSL_LIB_CTX(3)) and any property query string in propq. The ctx value
       may be NULL in which case the default library context is used. The
       propq value may also be NULL.

       EC_GROUP_new_by_curve_name() is the same as
       EC_GROUP_new_by_curve_name_ex() except that the default library context
       is always used along with a NULL property query string.

       EC_GROUP_free() frees the memory associated with the EC_GROUP. If group
       is NULL nothing is done.

       EC_GROUP_clear_free() is deprecated: it was meant to destroy any
       sensitive data held within the EC_GROUP and then free its memory, but
       since all the data stored in the EC_GROUP is public anyway, this
       function is unnecessary.  Its use can be safely replaced with
       EC_GROUP_free().  If group is NULL nothing is done.

       OSSL_EC_curve_nid2name() converts a curve nid into the corresponding

       All EC_GROUP_new* functions return a pointer to the newly constructed
       group, or NULL on error.

       EC_get_builtin_curves() returns the number of built-in curves that are

       EC_GROUP_set_curve_GFp(), EC_GROUP_get_curve_GFp(),
       EC_GROUP_set_curve_GF2m(), EC_GROUP_get_curve_GF2m() return 1 on
       success or 0 on error.

       OSSL_EC_curve_nid2name() returns a character string constant, or NULL
       on error.

       crypto(7), EC_GROUP_copy(3), EC_POINT_new(3), EC_POINT_add(3),
       EC_KEY_new(3), EC_GFp_simple_method(3), d2i_ECPKParameters(3),
       OSSL_LIB_CTX(3), EVP_PKEY-EC(7)

HISTORYEC_GROUP_new() was deprecated in OpenSSL 3.0.

         EC_GROUP_new_by_curve_name_ex() and EC_GROUP_new_from_params() were
         added in OpenSSL 3.0.

       ⊕ EC_GROUP_clear_free() was deprecated in OpenSSL 3.0; use
         EC_GROUP_free() instead.


          EC_GROUP_set_curve_GFp(), EC_GROUP_get_curve_GFp(),
          EC_GROUP_set_curve_GF2m() and EC_GROUP_get_curve_GF2m() were deprecated in
          OpenSSL 3.0; use EC_GROUP_set_curve() and EC_GROUP_get_curve() instead.

       Copyright 2013-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at

3.0.12                            2023-05-07                   EC_GROUP_new(3)