.\" Automatically generated by Pod::Man 4.11 (Pod::Simple 3.35)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
.    ds C`
.    ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\"
.\" If the F register is >0, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{\
.    if \nF \{\
.        de IX
.        tm Index:\\$1\t\\n%\t"\\$2"
..
.        if !\nF==2 \{\
.            nr % 0
.            nr F 2
.        \}
.    \}
.\}
.rr rF
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "RSA_set_method 3"
.TH RSA_set_method 3 "2019-12-20" "1.0.2u" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
RSA_set_default_method, RSA_get_default_method, RSA_set_method,
RSA_get_method, RSA_PKCS1_SSLeay, RSA_null_method, RSA_flags,
RSA_new_method \- select RSA method
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/rsa.h>
\&
\& void RSA_set_default_method(const RSA_METHOD *meth);
\&
\& RSA_METHOD *RSA_get_default_method(void);
\&
\& int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);
\&
\& RSA_METHOD *RSA_get_method(const RSA *rsa);
\&
\& RSA_METHOD *RSA_PKCS1_SSLeay(void);
\&
\& RSA_METHOD *RSA_null_method(void);
\&
\& int RSA_flags(const RSA *rsa);
\&
\& RSA *RSA_new_method(RSA_METHOD *method);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
An \fB\s-1RSA_METHOD\s0\fR specifies the functions that OpenSSL uses for \s-1RSA\s0
operations. By modifying the method, alternative implementations such as
hardware accelerators may be used. \s-1IMPORTANT:\s0 See the \s-1NOTES\s0 section for
important information about how these \s-1RSA API\s0 functions are affected by the
use of \fB\s-1ENGINE\s0\fR \s-1API\s0 calls.
.PP
Initially, the default \s-1RSA_METHOD\s0 is the OpenSSL internal implementation,
as returned by \fBRSA_PKCS1_SSLeay()\fR.
.PP
\&\fBRSA_set_default_method()\fR makes \fBmeth\fR the default method for all \s-1RSA\s0
structures created later. \fB\s-1NB\s0\fR: This is true only whilst no \s-1ENGINE\s0 has
been set as a default for \s-1RSA,\s0 so this function is no longer recommended.
.PP
\&\fBRSA_get_default_method()\fR returns a pointer to the current default
\&\s-1RSA_METHOD.\s0 However, the meaningfulness of this result is dependent on
whether the \s-1ENGINE API\s0 is being used, so this function is no longer 
recommended.
.PP
\&\fBRSA_set_method()\fR selects \fBmeth\fR to perform all operations using the key
\&\fBrsa\fR. This will replace the \s-1RSA_METHOD\s0 used by the \s-1RSA\s0 key and if the
previous method was supplied by an \s-1ENGINE,\s0 the handle to that \s-1ENGINE\s0 will
be released during the change. It is possible to have \s-1RSA\s0 keys that only
work with certain \s-1RSA_METHOD\s0 implementations (eg. from an \s-1ENGINE\s0 module
that supports embedded hardware-protected keys), and in such cases
attempting to change the \s-1RSA_METHOD\s0 for the key can have unexpected
results.
.PP
\&\fBRSA_get_method()\fR returns a pointer to the \s-1RSA_METHOD\s0 being used by \fBrsa\fR.
This method may or may not be supplied by an \s-1ENGINE\s0 implementation, but if
it is, the return value can only be guaranteed to be valid as long as the
\&\s-1RSA\s0 key itself is valid and does not have its implementation changed by
\&\fBRSA_set_method()\fR.
.PP
\&\fBRSA_flags()\fR returns the \fBflags\fR that are set for \fBrsa\fR's current
\&\s-1RSA_METHOD.\s0 See the \s-1BUGS\s0 section.
.PP
\&\fBRSA_new_method()\fR allocates and initializes an \s-1RSA\s0 structure so that
\&\fBengine\fR will be used for the \s-1RSA\s0 operations. If \fBengine\fR is \s-1NULL,\s0 the
default \s-1ENGINE\s0 for \s-1RSA\s0 operations is used, and if no default \s-1ENGINE\s0 is set,
the \s-1RSA_METHOD\s0 controlled by \fBRSA_set_default_method()\fR is used.
.PP
\&\fBRSA_flags()\fR returns the \fBflags\fR that are set for \fBrsa\fR's current method.
.PP
\&\fBRSA_new_method()\fR allocates and initializes an \fB\s-1RSA\s0\fR structure so that
\&\fBmethod\fR will be used for the \s-1RSA\s0 operations. If \fBmethod\fR is \fB\s-1NULL\s0\fR,
the default method is used.
.SH "THE RSA_METHOD STRUCTURE"
.IX Header "THE RSA_METHOD STRUCTURE"
.Vb 4
\& typedef struct rsa_meth_st
\& {
\&     /* name of the implementation */
\&        const char *name;
\&
\&     /* encrypt */
\&        int (*rsa_pub_enc)(int flen, unsigned char *from,
\&          unsigned char *to, RSA *rsa, int padding);
\&
\&     /* verify arbitrary data */
\&        int (*rsa_pub_dec)(int flen, unsigned char *from,
\&          unsigned char *to, RSA *rsa, int padding);
\&
\&     /* sign arbitrary data */
\&        int (*rsa_priv_enc)(int flen, unsigned char *from,
\&          unsigned char *to, RSA *rsa, int padding);
\&
\&     /* decrypt */
\&        int (*rsa_priv_dec)(int flen, unsigned char *from,
\&          unsigned char *to, RSA *rsa, int padding);
\&
\&     /* compute r0 = r0 ^ I mod rsa\->n (May be NULL for some
\&                                        implementations) */
\&        int (*rsa_mod_exp)(BIGNUM *r0, BIGNUM *I, RSA *rsa);
\&
\&     /* compute r = a ^ p mod m (May be NULL for some implementations) */
\&        int (*bn_mod_exp)(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
\&          const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
\&
\&     /* called at RSA_new */
\&        int (*init)(RSA *rsa);
\&
\&     /* called at RSA_free */
\&        int (*finish)(RSA *rsa);
\&
\&     /* RSA_FLAG_EXT_PKEY        \- rsa_mod_exp is called for private key
\&      *                            operations, even if p,q,dmp1,dmq1,iqmp
\&      *                            are NULL
\&      * RSA_FLAG_SIGN_VER        \- enable rsa_sign and rsa_verify
\&      * RSA_METHOD_FLAG_NO_CHECK \- don\*(Aqt check pub/private match
\&      */
\&        int flags;
\&
\&        char *app_data; /* ?? */
\&
\&     /* sign. For backward compatibility, this is used only
\&      * if (flags & RSA_FLAG_SIGN_VER)
\&      */
\&        int (*rsa_sign)(int type,
\&                const unsigned char *m, unsigned int m_length,
\&                unsigned char *sigret, unsigned int *siglen, const RSA *rsa);
\&     /* verify. For backward compatibility, this is used only
\&      * if (flags & RSA_FLAG_SIGN_VER)
\&      */
\&        int (*rsa_verify)(int dtype,
\&                const unsigned char *m, unsigned int m_length,
\&                const unsigned char *sigbuf, unsigned int siglen,
\&                                                                const RSA *rsa);
\&     /* keygen. If NULL builtin RSA key generation will be used */
\&        int (*rsa_keygen)(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
\&
\& } RSA_METHOD;
.Ve
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBRSA_PKCS1_SSLeay()\fR, \fBRSA_PKCS1_null_method()\fR, \fBRSA_get_default_method()\fR
and \fBRSA_get_method()\fR return pointers to the respective RSA_METHODs.
.PP
\&\fBRSA_set_default_method()\fR returns no value.
.PP
\&\fBRSA_set_method()\fR returns a pointer to the old \s-1RSA_METHOD\s0 implementation
that was replaced. However, this return value should probably be ignored
because if it was supplied by an \s-1ENGINE,\s0 the pointer could be invalidated
at any time if the \s-1ENGINE\s0 is unloaded (in fact it could be unloaded as a
result of the \fBRSA_set_method()\fR function releasing its handle to the
\&\s-1ENGINE\s0). For this reason, the return type may be replaced with a \fBvoid\fR
declaration in a future release.
.PP
\&\fBRSA_new_method()\fR returns \s-1NULL\s0 and sets an error code that can be obtained
by \fBERR_get_error\fR\|(3) if the allocation fails. Otherwise
it returns a pointer to the newly allocated structure.
.SH "NOTES"
.IX Header "NOTES"
As of version 0.9.7, \s-1RSA_METHOD\s0 implementations are grouped together with
other algorithmic APIs (eg. \s-1DSA_METHOD, EVP_CIPHER,\s0 etc) into \fB\s-1ENGINE\s0\fR
modules. If a default \s-1ENGINE\s0 is specified for \s-1RSA\s0 functionality using an
\&\s-1ENGINE API\s0 function, that will override any \s-1RSA\s0 defaults set using the \s-1RSA
API\s0 (ie.  \fBRSA_set_default_method()\fR). For this reason, the \s-1ENGINE API\s0 is the
recommended way to control default implementations for use in \s-1RSA\s0 and other
cryptographic algorithms.
.SH "BUGS"
.IX Header "BUGS"
The behaviour of \fBRSA_flags()\fR is a mis-feature that is left as-is for now
to avoid creating compatibility problems. \s-1RSA\s0 functionality, such as the
encryption functions, are controlled by the \fBflags\fR value in the \s-1RSA\s0 key
itself, not by the \fBflags\fR value in the \s-1RSA_METHOD\s0 attached to the \s-1RSA\s0 key
(which is what this function returns). If the flags element of an \s-1RSA\s0 key
is changed, the changes will be honoured by \s-1RSA\s0 functionality but will not
be reflected in the return value of the \fBRSA_flags()\fR function \- in effect
\&\fBRSA_flags()\fR behaves more like an \fBRSA_default_flags()\fR function (which does
not currently exist).
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBrsa\fR\|(3), \fBRSA_new\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fBRSA_new_method()\fR and \fBRSA_set_default_method()\fR appeared in SSLeay 0.8.
\&\fBRSA_get_default_method()\fR, \fBRSA_set_method()\fR and \fBRSA_get_method()\fR as
well as the rsa_sign and rsa_verify components of \s-1RSA_METHOD\s0 were
added in OpenSSL 0.9.4.
.PP
\&\fBRSA_set_default_openssl_method()\fR and \fBRSA_get_default_openssl_method()\fR
replaced \fBRSA_set_default_method()\fR and \fBRSA_get_default_method()\fR
respectively, and \fBRSA_set_method()\fR and \fBRSA_new_method()\fR were altered to use
\&\fB\s-1ENGINE\s0\fRs rather than \fB\s-1RSA_METHOD\s0\fRs during development of the engine
version of OpenSSL 0.9.6. For 0.9.7, the handling of defaults in the \s-1ENGINE
API\s0 was restructured so that this change was reversed, and behaviour of the
other functions resembled more closely the previous behaviour. The
behaviour of defaults in the \s-1ENGINE API\s0 now transparently overrides the
behaviour of defaults in the \s-1RSA API\s0 without requiring changing these
function prototypes.