aboutsummaryrefslogtreecommitdiff
path: root/doc/man3/EC_GROUP_new.pod
diff options
context:
space:
mode:
Diffstat (limited to 'doc/man3/EC_GROUP_new.pod')
-rw-r--r--doc/man3/EC_GROUP_new.pod102
1 files changed, 60 insertions, 42 deletions
diff --git a/doc/man3/EC_GROUP_new.pod b/doc/man3/EC_GROUP_new.pod
index 1eee494927f5..c80b191785c4 100644
--- a/doc/man3/EC_GROUP_new.pod
+++ b/doc/man3/EC_GROUP_new.pod
@@ -57,49 +57,63 @@ objects
=head1 DESCRIPTION
-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
+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:
+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 B<irreducible polynomial>. All such curves with OpenSSL
-use a trinomial or a pentanomial for this parameter.
-
-A new curve can be constructed by calling EC_GROUP_new, using the implementation provided by B<meth> (see
-L<EC_GFp_simple_method(3)>). It is then necessary to call EC_GROUP_set_curve() to set the curve parameters.
-EC_GROUP_new_from_ecparameters() will create a group from the
-specified B<params> and
-EC_GROUP_new_from_ecpkparameters() will create a group from the specific PK B<params>.
-
-EC_GROUP_set_curve() sets the curve parameters B<p>, B<a> and B<b>. For a curve over Fp B<b>
-is the prime for the field. For a curve over F2^m B<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.
+Operations in a binary field are performed relative to an B<irreducible
+polynomial>. All such curves with OpenSSL use a trinomial or a pentanomial for
+this parameter.
+
+A new curve can be constructed by calling EC_GROUP_new(), using the
+implementation provided by B<meth> (see L<EC_GFp_simple_method(3)>). It is then
+necessary to call EC_GROUP_set_curve() to set the curve parameters.
+EC_GROUP_new_from_ecparameters() will create a group from the specified
+B<params> and EC_GROUP_new_from_ecpkparameters() will create a group from the
+specific PK B<params>.
+
+EC_GROUP_set_curve() sets the curve parameters B<p>, B<a> and B<b>. For a curve
+over Fp B<p> is the prime for the field. For a curve over F2^m B<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, B<a> and B<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 B<r> should be an array of EC_builtin_curve structures of size B<nitems>. The function
-will populate the B<r> array with information about the builtin curves. If B<nitems> is less than the total number of
-curves available, then the first B<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 B<r> or
-not). Passing a NULL B<r>, or setting B<nitems> to 0 will do nothing other than return the total number of curves available.
+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 B<r> should be an array of
+EC_builtin_curve structures of size B<nitems>. The function will populate the
+B<r> array with information about the builtin curves. If B<nitems> is less than
+the total number of curves available, then the first B<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 B<r> or not). Passing a NULL B<r>, or setting B<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 {
@@ -107,24 +121,28 @@ The EC_builtin_curve structure is defined as follows:
const char *comment;
} EC_builtin_curve;
-Each EC_builtin_curve item has a unique integer id (B<nid>), and a human readable comment string describing the curve.
+Each EC_builtin_curve item has a unique integer id (B<nid>), and a human
+readable comment string describing the curve.
-In order to construct a builtin curve use the function EC_GROUP_new_by_curve_name and provide the B<nid> of the curve to
+In order to construct a builtin curve use the function
+EC_GROUP_new_by_curve_name() and provide the B<nid> of the curve to
be constructed.
-EC_GROUP_free frees the memory associated with the EC_GROUP.
+EC_GROUP_free() frees the memory associated with the EC_GROUP.
If B<group> is NULL nothing is done.
-EC_GROUP_clear_free destroys any sensitive data held within the EC_GROUP and then frees its memory.
-If B<group> is NULL nothing is done.
+EC_GROUP_clear_free() destroys any sensitive data held within the EC_GROUP and
+then frees its memory. If B<group> is NULL nothing is done.
=head1 RETURN VALUES
-All EC_GROUP_new* functions return a pointer to the newly constructed group, or NULL on error.
+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 builtin curves that are available.
+EC_get_builtin_curves() returns the number of builtin curves that are available.
-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.
+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.
=head1 SEE ALSO
@@ -134,7 +152,7 @@ L<EC_GFp_simple_method(3)>, L<d2i_ECPKParameters(3)>
=head1 COPYRIGHT
-Copyright 2013-2018 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2013-2019 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy