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There was recently an instance where a user was confused by the deprecation warnings in the docs. They believed the warning applied to the immediately preceding function declarations, when it fact it applied to the following function declarations. https://mta.openssl.org/pipermail/openssl-users/2021-December/014665.html We clarify the wording to make it clear that the warning applies to the following functions. Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/17180)
234 lines
9.2 KiB
Plaintext
234 lines
9.2 KiB
Plaintext
=pod
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=head1 NAME
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EC_GROUP_get_ecparameters,
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EC_GROUP_get_ecpkparameters,
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EC_GROUP_new_from_params,
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EC_GROUP_new_from_ecparameters,
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EC_GROUP_new_from_ecpkparameters,
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EC_GROUP_new,
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EC_GROUP_free,
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EC_GROUP_clear_free,
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EC_GROUP_new_curve_GFp,
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EC_GROUP_new_curve_GF2m,
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EC_GROUP_new_by_curve_name_ex,
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EC_GROUP_new_by_curve_name,
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EC_GROUP_set_curve,
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EC_GROUP_get_curve,
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EC_GROUP_set_curve_GFp,
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EC_GROUP_get_curve_GFp,
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EC_GROUP_set_curve_GF2m,
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EC_GROUP_get_curve_GF2m,
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EC_get_builtin_curves,
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OSSL_EC_curve_nid2name -
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Functions for creating and destroying EC_GROUP objects
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=head1 SYNOPSIS
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#include <openssl/ec.h>
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EC_GROUP *EC_GROUP_new_from_params(const OSSL_PARAM params[],
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OSSL_LIB_CTX *libctx, const char *propq);
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EC_GROUP *EC_GROUP_new_from_ecparameters(const ECPARAMETERS *params);
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EC_GROUP *EC_GROUP_new_from_ecpkparameters(const ECPKPARAMETERS *params);
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void EC_GROUP_free(EC_GROUP *group);
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EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a,
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const BIGNUM *b, BN_CTX *ctx);
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EC_GROUP *EC_GROUP_new_curve_GF2m(const BIGNUM *p, const BIGNUM *a,
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const BIGNUM *b, BN_CTX *ctx);
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EC_GROUP *EC_GROUP_new_by_curve_name_ex(OSSL_LIB_CTX *libctx, const char *propq,
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int nid);
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EC_GROUP *EC_GROUP_new_by_curve_name(int nid);
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int EC_GROUP_set_curve(EC_GROUP *group, const BIGNUM *p, const BIGNUM *a,
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const BIGNUM *b, BN_CTX *ctx);
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int EC_GROUP_get_curve(const EC_GROUP *group, BIGNUM *p, BIGNUM *a, BIGNUM *b,
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BN_CTX *ctx);
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ECPARAMETERS *EC_GROUP_get_ecparameters(const EC_GROUP *group,
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ECPARAMETERS *params);
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ECPKPARAMETERS *EC_GROUP_get_ecpkparameters(const EC_GROUP *group,
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ECPKPARAMETERS *params);
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size_t EC_get_builtin_curves(EC_builtin_curve *r, size_t nitems);
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const char *OSSL_EC_curve_nid2name(int nid);
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The following functions have been deprecated since OpenSSL 3.0, and can be
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hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
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see L<openssl_user_macros(7)>:
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EC_GROUP *EC_GROUP_new(const EC_METHOD *meth);
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void EC_GROUP_clear_free(EC_GROUP *group);
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int EC_GROUP_set_curve_GFp(EC_GROUP *group, const BIGNUM *p,
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const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
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int EC_GROUP_get_curve_GFp(const EC_GROUP *group, BIGNUM *p,
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BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
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int EC_GROUP_set_curve_GF2m(EC_GROUP *group, const BIGNUM *p,
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const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx);
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int EC_GROUP_get_curve_GF2m(const EC_GROUP *group, BIGNUM *p,
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BIGNUM *a, BIGNUM *b, BN_CTX *ctx);
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=head1 DESCRIPTION
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Within the library there are two forms of elliptic curve that are of interest.
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The first form is those defined over the prime field Fp. The elements of Fp are
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the integers 0 to p-1, where p is a prime number. This gives us a revised
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elliptic curve equation as follows:
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y^2 mod p = x^3 +ax + b mod p
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The second form is those defined over a binary field F2^m where the elements of
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the field are integers of length at most m bits. For this form the elliptic
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curve equation is modified to:
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y^2 + xy = x^3 + ax^2 + b (where b != 0)
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Operations in a binary field are performed relative to an
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B<irreducible polynomial>. All such curves with OpenSSL use a trinomial or a
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pentanomial for this parameter.
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Although deprecated since OpenSSL 3.0 and should no longer be used,
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a new curve can be constructed by calling EC_GROUP_new(), using the
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implementation provided by I<meth> (see L<EC_GFp_simple_method(3)>) and
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associated with the library context I<ctx> (see L<OSSL_LIB_CTX(3)>).
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The I<ctx> parameter may be NULL in which case the default library context is
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used.
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It is then necessary to call EC_GROUP_set_curve() to set the curve parameters.
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Applications should instead use one of the other EC_GROUP_new_* constructors.
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EC_GROUP_new_from_params() creates a group with parameters specified by I<params>.
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The library context I<libctx> (see L<OSSL_LIB_CTX(3)>) and property query string
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I<propq> are used to fetch algorithms from providers.
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I<params> may be either a list of explicit params or a named group,
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The values for I<ctx> and I<propq> may be NULL.
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The I<params> that can be used are described in
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L<B<EVP_PKEY-EC>(7)|EVP_PKEY-EC(7)/Common EC parameters>.
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EC_GROUP_new_from_ecparameters() will create a group from the
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specified I<params> and
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EC_GROUP_new_from_ecpkparameters() will create a group from the specific PK
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I<params>.
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EC_GROUP_set_curve() sets the curve parameters I<p>, I<a> and I<b>. For a curve
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over Fp I<p> is the prime for the field. For a curve over F2^m I<p> represents
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the irreducible polynomial - each bit represents a term in the polynomial.
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Therefore, there will either be three or five bits set dependent on whether the
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polynomial is a trinomial or a pentanomial.
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In either case, I<a> and I<b> represents the coefficients a and b from the
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relevant equation introduced above.
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EC_group_get_curve() obtains the previously set curve parameters.
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EC_GROUP_set_curve_GFp() and EC_GROUP_set_curve_GF2m() are synonyms for
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EC_GROUP_set_curve(). They are defined for backwards compatibility only and
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should not be used.
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EC_GROUP_get_curve_GFp() and EC_GROUP_get_curve_GF2m() are synonyms for
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EC_GROUP_get_curve(). They are defined for backwards compatibility only and
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should not be used.
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The functions EC_GROUP_new_curve_GFp() and EC_GROUP_new_curve_GF2m() are
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shortcuts for calling EC_GROUP_new() and then the EC_GROUP_set_curve() function.
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An appropriate default implementation method will be used.
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Whilst the library can be used to create any curve using the functions described
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above, there are also a number of predefined curves that are available. In order
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to obtain a list of all of the predefined curves, call the function
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EC_get_builtin_curves(). The parameter I<r> should be an array of
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EC_builtin_curve structures of size I<nitems>. The function will populate the
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I<r> array with information about the built-in curves. If I<nitems> is less than
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the total number of curves available, then the first I<nitems> curves will be
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returned. Otherwise the total number of curves will be provided. The return
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value is the total number of curves available (whether that number has been
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populated in I<r> or not). Passing a NULL I<r>, or setting I<nitems> to 0 will
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do nothing other than return the total number of curves available.
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The EC_builtin_curve structure is defined as follows:
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typedef struct {
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int nid;
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const char *comment;
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} EC_builtin_curve;
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Each EC_builtin_curve item has a unique integer id (I<nid>), and a human
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readable comment string describing the curve.
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In order to construct a built-in curve use the function
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EC_GROUP_new_by_curve_name_ex() and provide the I<nid> of the curve to
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be constructed, the associated library context to be used in I<ctx> (see
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L<OSSL_LIB_CTX(3)>) and any property query string in I<propq>. The I<ctx> value
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may be NULL in which case the default library context is used. The I<propq>
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value may also be NULL.
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EC_GROUP_new_by_curve_name() is the same as
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EC_GROUP_new_by_curve_name_ex() except that the default library context
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is always used along with a NULL property query string.
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EC_GROUP_free() frees the memory associated with the EC_GROUP.
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If I<group> is NULL nothing is done.
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EC_GROUP_clear_free() is deprecated: it was meant to destroy any sensitive data
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held within the EC_GROUP and then free its memory, but since all the data stored
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in the EC_GROUP is public anyway, this function is unnecessary.
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Its use can be safely replaced with EC_GROUP_free().
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If I<group> is NULL nothing is done.
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OSSL_EC_curve_nid2name() converts a curve I<nid> into the corresponding name.
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=head1 RETURN VALUES
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All EC_GROUP_new* functions return a pointer to the newly constructed group, or
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NULL on error.
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EC_get_builtin_curves() returns the number of built-in curves that are
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available.
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EC_GROUP_set_curve_GFp(), EC_GROUP_get_curve_GFp(), EC_GROUP_set_curve_GF2m(),
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EC_GROUP_get_curve_GF2m() return 1 on success or 0 on error.
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OSSL_EC_curve_nid2name() returns a character string constant, or NULL on error.
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=head1 SEE ALSO
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L<crypto(7)>, L<EC_GROUP_copy(3)>,
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L<EC_POINT_new(3)>, L<EC_POINT_add(3)>, L<EC_KEY_new(3)>,
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L<EC_GFp_simple_method(3)>, L<d2i_ECPKParameters(3)>,
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L<OSSL_LIB_CTX(3)>, L<EVP_PKEY-EC(7)>
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=head1 HISTORY
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=over 2
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=item *
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EC_GROUP_new() was deprecated in OpenSSL 3.0.
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EC_GROUP_new_by_curve_name_ex() and EC_GROUP_new_from_params() were
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added in OpenSSL 3.0.
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=item *
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EC_GROUP_clear_free() was deprecated in OpenSSL 3.0; use EC_GROUP_free()
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instead.
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=item *
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EC_GROUP_set_curve_GFp(), EC_GROUP_get_curve_GFp(),
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EC_GROUP_set_curve_GF2m() and EC_GROUP_get_curve_GF2m() were deprecated in
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OpenSSL 3.0; use EC_GROUP_set_curve() and EC_GROUP_get_curve() instead.
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=back
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=head1 COPYRIGHT
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Copyright 2013-2021 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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