int EC_GROUP_get_asn1_flag(const EC_GROUP *group);
void EC_GROUP_set_point_conversion_form(EC_GROUP *group, point_conversion_form_t form);
- point_conversion_form_t EC_GROUP_get_point_conversion_form(const EC_GROUP *);
+ point_conversion_form_t EC_GROUP_get_point_conversion_form(const EC_GROUP *group);
unsigned char *EC_GROUP_get0_seed(const EC_GROUP *x);
size_t EC_GROUP_get_seed_len(const EC_GROUP *);
=head1 DESCRIPTION
-EC_GROUP_copy copies the curve B<src> into B<dst>. Both B<src> and B<dst> must use the same EC_METHOD.
+EC_GROUP_copy() copies the curve B<src> into B<dst>. Both B<src> and B<dst> must use the same EC_METHOD.
-EC_GROUP_dup creates a new EC_GROUP object and copies the content from B<src> to the newly created
+EC_GROUP_dup() creates a new EC_GROUP object and copies the content from B<src> to the newly created
EC_GROUP object.
-EC_GROUP_method_of obtains the EC_METHOD of B<group>.
+EC_GROUP_method_of() obtains the EC_METHOD of B<group>.
-EC_GROUP_set_generator sets curve parameters that must be agreed by all participants using the curve. These
+EC_GROUP_set_generator() sets curve parameters that must be agreed by all participants using the curve. These
parameters include the B<generator>, the B<order> and the B<cofactor>. The B<generator> is a well defined point on the
curve chosen for cryptographic operations. Integers used for point multiplications will be between 0 and
n-1 where n is the B<order>. The B<order> multiplied by the B<cofactor> gives the number of points on the curve.
-EC_GROUP_get0_generator returns the generator for the identified B<group>.
+EC_GROUP_get0_generator() returns the generator for the identified B<group>.
-The functions EC_GROUP_get_order and EC_GROUP_get_cofactor populate the provided B<order> and B<cofactor> parameters
-with the respective order and cofactors for the B<group>.
+EC_GROUP_get_order() retrieves the order of B<group> and copies its value into
+B<order>. It fails in case B<group> is not fully initialized (i.e., its order
+is not set or set to zero).
-The functions EC_GROUP_set_curve_name and EC_GROUP_get_curve_name, set and get the NID for the curve respectively
+EC_GROUP_get_cofactor() retrieves the cofactor of B<group> and copies its value
+into B<cofactor>. It fails in case B<group> is not fully initialized or if the
+cofactor is not set (or set to zero).
+
+The functions EC_GROUP_set_curve_name() and EC_GROUP_get_curve_name(), set and get the NID for the curve respectively
(see L<EC_GROUP_new(3)>). If a curve does not have a NID associated with it, then EC_GROUP_get_curve_name
-will return 0.
+will return NID_undef.
The asn1_flag value is used to determine whether the curve encoding uses
explicit parameters or a named curve using an ASN1 OID: many applications only
support the latter form. If asn1_flag is B<OPENSSL_EC_NAMED_CURVE> then the
named curve form is used and the parameters must have a corresponding
named curve NID set. If asn1_flags is B<OPENSSL_EC_EXPLICIT_CURVE> the
-parameters are explicitly encoded. The functions EC_GROUP_get_asn1_flag and
-EC_GROUP_set_asn1_flag get and set the status of the asn1_flag for the curve.
+parameters are explicitly encoded. The functions EC_GROUP_get_asn1_flag() and
+EC_GROUP_set_asn1_flag() get and set the status of the asn1_flag for the curve.
Note: B<OPENSSL_EC_EXPLICIT_CURVE> was added in OpenSSL 1.1.0, for
previous versions of OpenSSL the value 0 must be used instead. Before OpenSSL
1.1.0 the default form was to use explicit parameters (meaning that
For POINT_CONVERSION_HYBRID the point is encoded as an octet signifying the HYBRID form has been used AND which of the two
possible solutions for y has been used, followed by the octets for x, followed by the octets for y.
-The functions EC_GROUP_set_point_conversion_form and EC_GROUP_get_point_conversion_form set and get the point_conversion_form
+The functions EC_GROUP_set_point_conversion_form() and EC_GROUP_get_point_conversion_form(), set and get the point_conversion_form
for the curve respectively.
ANSI X9.62 (ECDSA standard) defines a method of generating the curve parameter b from a random number. This provides advantages
in that a parameter obtained in this way is highly unlikely to be susceptible to special purpose attacks, or have any trapdoors in it.
If the seed is present for a curve then the b parameter was generated in a verifiable fashion using that seed. The OpenSSL EC library
-does not use this seed value but does enable you to inspect it using EC_GROUP_get0_seed. This returns a pointer to a memory block
-containing the seed that was used. The length of the memory block can be obtained using EC_GROUP_get_seed_len. A number of the
-builtin curves within the library provide seed values that can be obtained. It is also possible to set a custom seed using
-EC_GROUP_set_seed and passing a pointer to a memory block, along with the length of the seed. Again, the EC library will not use
+does not use this seed value but does enable you to inspect it using EC_GROUP_get0_seed(). This returns a pointer to a memory block
+containing the seed that was used. The length of the memory block can be obtained using EC_GROUP_get_seed_len(). A number of the
+built-in curves within the library provide seed values that can be obtained. It is also possible to set a custom seed using
+EC_GROUP_set_seed() and passing a pointer to a memory block, along with the length of the seed. Again, the EC library will not use
this seed value, although it will be preserved in any ASN1 based communications.
-EC_GROUP_get_degree gets the degree of the field. For Fp fields this will be the number of bits in p. For F2^m fields this will be
+EC_GROUP_get_degree() gets the degree of the field. For Fp fields this will be the number of bits in p. For F2^m fields this will be
the value m.
-The function EC_GROUP_check_discriminant calculates the discriminant for the curve and verifies that it is valid.
+The function EC_GROUP_check_discriminant() calculates the discriminant for the curve and verifies that it is valid.
For a curve defined over Fp the discriminant is given by the formula 4*a^3 + 27*b^2 whilst for F2^m curves the discriminant is
simply b. In either case for the curve to be valid the discriminant must be non zero.
-The function EC_GROUP_check performs a number of checks on a curve to verify that it is valid. Checks performed include
+The function EC_GROUP_check() performs a number of checks on a curve to verify that it is valid. Checks performed include
verifying that the discriminant is non zero; that a generator has been defined; that the generator is on the curve and has
the correct order.
-EC_GROUP_cmp compares B<a> and B<b> to determine whether they represent the same curve or not.
+EC_GROUP_cmp
() compares B<a> and B<b> to determine whether they represent the same curve or not.
-The functions EC_GROUP_get_basis_type, EC_GROUP_get_trinomial_basis and EC_GROUP_get_pentanomial_basis should only be called for curves
+The functions EC_GROUP_get_basis_type(), EC_GROUP_get_trinomial_basis() and EC_GROUP_get_pentanomial_basis() should only be called for curves
defined over an F2^m field. Addition and multiplication operations within an F2^m field are performed using an irreducible polynomial
function f(x). This function is either a trinomial of the form:
f(x) = x^m + x^k3 + x^k2 + x^k1 + 1 with m > k3 > k2 > k1 >= 1
-The function EC_GROUP_get_basis_type returns a NID identifying whether a trinomial or pentanomial is in use for the field. The
-function EC_GROUP_get_trinomial_basis must only be called where f(x) is of the trinomial form, and returns the value of B<k>. Similarly
-the function EC_GROUP_get_pentanomial_basis must only be called where f(x) is of the pentanomial form, and returns the values of B<k1>,
+The function EC_GROUP_get_basis_type() returns a NID identifying whether a trinomial or pentanomial is in use for the field. The
+function EC_GROUP_get_trinomial_basis() must only be called where f(x) is of the trinomial form, and returns the value of B<k>. Similarly
+the function EC_GROUP_get_pentanomial_basis() must only be called where f(x) is of the pentanomial form, and returns the values of B<k1>,
B<k2> and B<k3> respectively.
=head1 RETURN VALUES
-The following functions return 1 on success or 0 on error: EC_GROUP_copy, EC_GROUP_set_generator, EC_GROUP_check,
-EC_GROUP_check_discriminant, EC_GROUP_get_trinomial_basis and EC_GROUP_get_pentanomial_basis.
+The following functions return 1 on success or 0 on error: EC_GROUP_copy(), EC_GROUP_set_generator(), EC_GROUP_check(),
+EC_GROUP_check_discriminant(), EC_GROUP_get_trinomial_basis() and EC_GROUP_get_pentanomial_basis().
+
+EC_GROUP_dup() returns a pointer to the duplicated curve, or NULL on error.
+
+EC_GROUP_method_of() returns the EC_METHOD implementation in use for the given curve or NULL on error.
+
+EC_GROUP_get0_generator() returns the generator for the given curve or NULL on error.
+
+EC_GROUP_get_order() returns 0 if the order is not set (or set to zero) for
+B<group> or if copying into B<order> fails, 1 otherwise.
+
+EC_GROUP_get_cofactor() returns 0 if the cofactor is not set (or is set to zero) for B<group> or if copying into B<cofactor> fails, 1 otherwise.
-EC_GROUP_dup returns a pointer to the duplicated curve, or NULL on error.
+EC_GROUP_get_curve_name() returns the curve name (NID) for B<group> or will return NID_undef if no curve name is associated.
-EC_GROUP_method_of returns the EC_METHOD implementation in use for the given curve or NULL on error.
+EC_GROUP_get_asn1_flag() returns the ASN1 flag for the specified B<group> .
-EC_GROUP_get0_generator returns the generator for the given curve or NULL on error.
+EC_GROUP_get_point_conversion_form() returns the point_conversion_form for B<group>.
-EC_GROUP_get_order, EC_GROUP_get_cofactor, EC_GROUP_get_curve_name, EC_GROUP_get_asn1_flag, EC_GROUP_get_point_conversion_form
-and EC_GROUP_get_degree return the order, cofactor, curve name (NID), ASN1 flag, point_conversion_form and degree for the
-specified curve respectively. If there is no curve name associated with a curve then EC_GROUP_get_curve_name will return 0.
+EC_GROUP_get_degree() returns the degree for B<group> or 0 if the operation is not supported by the underlying group implementation.
EC_GROUP_get0_order() returns an internal pointer to the group order.
EC_GROUP_order_bits() returns the number of bits in the group order.
EC_GROUP_get0_cofactor() returns an internal pointer to the group cofactor.
-EC_GROUP_get0_seed returns a pointer to the seed that was used to generate the parameter b, or NULL if the seed is not
-specified. EC_GROUP_get_seed_len returns the length of the seed or 0 if the seed is not specified.
+EC_GROUP_get0_seed() returns a pointer to the seed that was used to generate the parameter b, or NULL if the seed is not
+specified. EC_GROUP_get_seed_len() returns the length of the seed or 0 if the seed is not specified.
-EC_GROUP_set_seed returns the length of the seed that has been set. If the supplied seed is NULL, or the supplied seed length is
+EC_GROUP_set_seed() returns the length of the seed that has been set. If the supplied seed is NULL, or the supplied seed length is
0, the return value will be 1. On error 0 is returned.
-EC_GROUP_cmp returns 0 if the curves are equal, 1 if they are not equal, or -1 on error.
+EC_GROUP_cmp() returns 0 if the curves are equal, 1 if they are not equal, or -1 on error.
-EC_GROUP_get_basis_type returns the values NID_X9_62_tpBasis or NID_X9_62_ppBasis (as defined in <openssl/obj_mac.h>) for a
+EC_GROUP_get_basis_type() returns the values NID_X9_62_tpBasis or NID_X9_62_ppBasis (as defined in <openssl/obj_mac.h>) for a
trinomial or pentanomial respectively. Alternatively in the event of an error a 0 is returned.
=head1 SEE ALSO
projects / oweals / openssl.git / commitdiff