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| 1 | =pod | ||
| 2 | |||
| 3 | =head1 NAME | ||
| 4 | |||
| 5 | EC_GFp_simple_method, EC_GFp_mont_method, EC_GFp_nist_method, EC_GFp_nistp224_method, EC_GFp_nistp256_method, EC_GFp_nistp521_method, EC_GF2m_simple_method, EC_METHOD_get_field_type - Functions for obtaining B<EC_METHOD> objects. | ||
| 6 | |||
| 7 | =head1 SYNOPSIS | ||
| 8 | |||
| 9 | #include <openssl/ec.h> | ||
| 10 | |||
| 11 | const EC_METHOD *EC_GFp_simple_method(void); | ||
| 12 | const EC_METHOD *EC_GFp_mont_method(void); | ||
| 13 | const EC_METHOD *EC_GFp_nist_method(void); | ||
| 14 | const EC_METHOD *EC_GFp_nistp224_method(void); | ||
| 15 | const EC_METHOD *EC_GFp_nistp256_method(void); | ||
| 16 | const EC_METHOD *EC_GFp_nistp521_method(void); | ||
| 17 | |||
| 18 | const EC_METHOD *EC_GF2m_simple_method(void); | ||
| 19 | |||
| 20 | int EC_METHOD_get_field_type(const EC_METHOD *meth); | ||
| 21 | |||
| 22 | =head1 DESCRIPTION | ||
| 23 | |||
| 24 | The Elliptic Curve library provides a number of different implementations through a single common interface. | ||
| 25 | When constructing a curve using EC_GROUP_new (see L<EC_GROUP_new(3)|EC_GROUP_new(3)>) an | ||
| 26 | implementation method must be provided. The functions described here all return a const pointer to an | ||
| 27 | B<EC_METHOD> structure that can be passed to EC_GROUP_NEW. It is important that the correct implementation | ||
| 28 | type for the form of curve selected is used. | ||
| 29 | |||
| 30 | For F2^m curves there is only one implementation choice, i.e. EC_GF2_simple_method. | ||
| 31 | |||
| 32 | For Fp curves the lowest common denominator implementation is the EC_GFp_simple_method implementation. All | ||
| 33 | other implementations are based on this one. EC_GFp_mont_method builds on EC_GFp_simple_method but adds the | ||
| 34 | use of montgomery multiplication (see L<BN_mod_mul_montgomery(3)|BN_mod_mul_montgomery(3)>). EC_GFp_nist_method | ||
| 35 | offers an implementation optimised for use with NIST recommended curves (NIST curves are available through | ||
| 36 | EC_GROUP_new_by_curve_name as described in L<EC_GROUP_new(3)|EC_GROUP_new(3)>). | ||
| 37 | |||
| 38 | The functions EC_GFp_nistp224_method, EC_GFp_nistp256_method and EC_GFp_nistp521_method offer 64 bit | ||
| 39 | optimised implementations for the NIST P224, P256 and P521 curves respectively. Note, however, that these | ||
| 40 | implementations are not available on all platforms. | ||
| 41 | |||
| 42 | EC_METHOD_get_field_type identifies what type of field the EC_METHOD structure supports, which will be either | ||
| 43 | F2^m or Fp. If the field type is Fp then the value B<NID_X9_62_prime_field> is returned. If the field type is | ||
| 44 | F2^m then the value B<NID_X9_62_characteristic_two_field> is returned. These values are defined in the | ||
| 45 | obj_mac.h header file. | ||
| 46 | |||
| 47 | =head1 RETURN VALUES | ||
| 48 | |||
| 49 | All EC_GFp* functions and EC_GF2m_simple_method always return a const pointer to an EC_METHOD structure. | ||
| 50 | |||
| 51 | EC_METHOD_get_field_type returns an integer that identifies the type of field the EC_METHOD structure supports. | ||
| 52 | |||
| 53 | =head1 SEE ALSO | ||
| 54 | |||
| 55 | L<crypto(3)|crypto(3)>, L<ec(3)|ec(3)>, L<EC_GROUP_new(3)|EC_GROUP_new(3)>, L<EC_GROUP_copy(3)|EC_GROUP_copy(3)>, | ||
| 56 | L<EC_POINT_new(3)|EC_POINT_new(3)>, L<EC_POINT_add(3)|EC_POINT_add(3)>, L<EC_KEY_new(3)|EC_KEY_new(3)>, | ||
| 57 | L<d2i_ECPKParameters(3)|d2i_ECPKParameters(3)>, | ||
| 58 | L<BN_mod_mul_montgomery(3)|BN_mod_mul_montgomery(3)> | ||
| 59 | |||
| 60 | =cut | ||
