.\" $OpenBSD: RSA_meth_new.3,v 1.5 2019/07/13 17:26:38 schwarze Exp $
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.\" The original file was written by Richard Levitte <levitte@openssl.org>.
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.Dd $Mdocdate: July 13 2019 $
.Dt RSA_METH_NEW 3
.Os
.Sh NAME
.Nm RSA_meth_new ,
.Nm RSA_meth_dup ,
.Nm RSA_meth_free ,
.Nm RSA_meth_get0_name ,
.Nm RSA_meth_set1_name ,
.Nm RSA_meth_get_flags ,
.Nm RSA_meth_set_flags ,
.Nm RSA_meth_get0_app_data ,
.Nm RSA_meth_set0_app_data ,
.Nm RSA_meth_get_init ,
.Nm RSA_meth_set_init ,
.Nm RSA_meth_get_finish ,
.Nm RSA_meth_set_finish ,
.Nm RSA_meth_get_pub_enc ,
.Nm RSA_meth_set_pub_enc ,
.Nm RSA_meth_get_pub_dec ,
.Nm RSA_meth_set_pub_dec ,
.Nm RSA_meth_get_priv_enc ,
.Nm RSA_meth_set_priv_enc ,
.Nm RSA_meth_get_priv_dec ,
.Nm RSA_meth_set_priv_dec ,
.Nm RSA_meth_get_sign ,
.Nm RSA_meth_set_sign ,
.Nm RSA_meth_get_verify ,
.Nm RSA_meth_set_verify ,
.Nm RSA_meth_get_mod_exp ,
.Nm RSA_meth_set_mod_exp ,
.Nm RSA_meth_get_bn_mod_exp ,
.Nm RSA_meth_set_bn_mod_exp ,
.Nm RSA_meth_get_keygen ,
.Nm RSA_meth_set_keygen
.Nd build up RSA methods
.Sh SYNOPSIS
.In openssl/rsa.h
.Ft RSA_METHOD *
.Fo RSA_meth_new
.Fa "const char *name"
.Fa "int flags"
.Fc
.Ft RSA_METHOD *
.Fo RSA_meth_dup
.Fa "const RSA_METHOD *meth"
.Fc
.Ft void
.Fo RSA_meth_free
.Fa "RSA_METHOD *meth"
.Fc
.Ft const char *
.Fo RSA_meth_get0_name
.Fa "const RSA_METHOD *meth"
.Fc
.Ft int
.Fo RSA_meth_set1_name
.Fa "RSA_METHOD *meth"
.Fa "const char *name"
.Fc
.Ft int
.Fo RSA_meth_get_flags
.Fa "const RSA_METHOD *meth"
.Fc
.Ft int
.Fo RSA_meth_set_flags
.Fa "RSA_METHOD *meth"
.Fa "int flags"
.Fc
.Ft void *
.Fo RSA_meth_get0_app_data
.Fa "const RSA_METHOD *meth"
.Fc
.Ft int
.Fo RSA_meth_set0_app_data
.Fa "RSA_METHOD *meth"
.Fa "void *app_data"
.Fc
.Ft int
.Fo "(*RSA_meth_get_init(const RSA_METHOD *meth))"
.Fa "RSA *rsa"
.Fc
.Ft int
.Fo "RSA_meth_set_init"
.Fa "RSA_METHOD *meth"
.Fa "int (*init)(RSA *rsa)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_finish(const RSA_METHOD *meth))"
.Fa "RSA *rsa"
.Fc
.Ft int
.Fo RSA_meth_set_finish
.Fa "RSA_METHOD *meth"
.Fa "int (*finish)(RSA *rsa)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_pub_enc(const RSA_METHOD *meth))"
.Fa "int flen"
.Fa "const unsigned char *from"
.Fa "unsigned char *to"
.Fa "RSA *rsa"
.Fa "int padding"
.Fc
.Ft int
.Fo RSA_meth_set_pub_enc
.Fa "RSA_METHOD *meth"
.Fa "int (*pub_enc)(int flen, const unsigned char *from,\
 unsigned char *to, RSA *rsa, int padding)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_pub_dec(const RSA_METHOD *meth))"
.Fa "int flen"
.Fa "const unsigned char *from"
.Fa "unsigned char *to"
.Fa "RSA *rsa"
.Fa "int padding"
.Fc
.Ft int
.Fo RSA_meth_set_pub_dec
.Fa "RSA_METHOD *meth"
.Fa "int (*pub_dec)(int flen, const unsigned char *from,\
 unsigned char *to, RSA *rsa, int padding)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_priv_enc(const RSA_METHOD *meth))"
.Fa "int flen"
.Fa "const unsigned char *from"
.Fa "unsigned char *to"
.Fa "RSA *rsa"
.Fa "int padding"
.Fc
.Ft int
.Fo RSA_meth_set_priv_enc
.Fa "RSA_METHOD *meth"
.Fa "int (*priv_enc)(int flen, const unsigned char *from,\
 unsigned char *to, RSA *rsa, int padding)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_priv_dec(const RSA_METHOD *meth))"
.Fa "int flen"
.Fa "const unsigned char *from"
.Fa "unsigned char *to"
.Fa "RSA *rsa"
.Fa "int padding"
.Fc
.Ft int
.Fo RSA_meth_set_priv_dec
.Fa "RSA_METHOD *meth"
.Fa "int (*priv_dec)(int flen, const unsigned char *from,\
 unsigned char *to, RSA *rsa, int padding)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_sign(const RSA_METHOD *meth))"
.Fa "int type"
.Fa "const unsigned char *m"
.Fa "unsigned int m_length"
.Fa "unsigned char *sigret"
.Fa "unsigned int *siglen"
.Fa "const RSA *rsa"
.Fc
.Ft int
.Fo RSA_meth_set_sign
.Fa "RSA_METHOD *rsa"
.Fa "int (*sign)(int type, const unsigned char *m, unsigned int m_length,\
 unsigned char *sigret, unsigned int *siglen, const RSA *rsa)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_verify(const RSA_METHOD *meth))"
.Fa "int dtype"
.Fa "const unsigned char *m"
.Fa "unsigned int m_length"
.Fa "const unsigned char *sigbuf"
.Fa "unsigned int siglen"
.Fa "const RSA *rsa"
.Fc
.Ft int
.Fo RSA_meth_set_verify
.Fa "RSA_METHOD *rsa"
.Fa "int (*verify)(int dtype, const unsigned char *m,\
 unsigned int m_length, const unsigned char *sigbuf,\
 unsigned int siglen, const RSA *rsa)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_mod_exp(const RSA_METHOD *meth))"
.Fa "BIGNUM *r0"
.Fa "const BIGNUM *i"
.Fa "RSA *rsa"
.Fa "BN_CTX *ctx"
.Fc
.Ft int
.Fo RSA_meth_set_mod_exp
.Fa "RSA_METHOD *meth"
.Fa "int (*mod_exp)(BIGNUM *r0, const BIGNUM *i, RSA *rsa, BN_CTX *ctx)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_bn_mod_exp(const RSA_METHOD *meth))"
.Fa "BIGNUM *r"
.Fa "const BIGNUM *a"
.Fa "const BIGNUM *p"
.Fa "const BIGNUM *m"
.Fa "BN_CTX *ctx"
.Fa "BN_MONT_CTX *m_ctx"
.Fc
.Ft int
.Fo RSA_meth_set_bn_mod_exp
.Fa "RSA_METHOD *meth"
.Fa "int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,\
 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)"
.Fc
.Ft int
.Fo "(*RSA_meth_get_keygen(const RSA_METHOD *meth))"
.Fa "RSA *rsa"
.Fa "int bits"
.Fa "BIGNUM *e"
.Fa "BN_GENCB *cb"
.Fc
.Ft int
.Fo RSA_meth_set_keygen
.Fa "RSA_METHOD *meth"
.Fa "int (*keygen)(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb)"
.Fc
.Sh DESCRIPTION
The
.Vt RSA_METHOD
structure holds function pointers for custom RSA implementations.
.Pp
.Fn RSA_meth_new
creates a new
.Vt RSA_METHOD
structure.
A copy of the NUL-terminated
.Fa name
is stored in the new
.Vt RSA_METHOD
object.
Any new
.Vt RSA
object constructed from this
.Vt RSA_METHOD
will have the given
.Fa flags
set by default, as if they were set with
.Xr RSA_set_flags 3 .
.Pp
.Fn RSA_meth_dup
creates a deep copy of
.Fa meth ,
except that a pointer stored into it with
.Fn RSA_meth_set0_app_data
is copied as a pointer without creating a copy of its content.
This might be useful for creating a new
.Vt RSA_METHOD
based on an existing one, but with some differences.
.Pp
.Fn RSA_meth_free
destroys
.Fa meth
and frees any memory associated with it,
except that memory pointed to by a pointer set with
.Fn RSA_meth_set0_app_data
is not freed.
If
.Fa meth
is
.Dv NULL ,
no action occurs.
.Pp
.Fn RSA_meth_get0_name
returns an internal pointer to the name of
.Fa meth .
.Fn RSA_meth_set1_name
stores a copy of the NUL-terminated
.Fa name
in the
.Vt RSA_METHOD
object after freeing the previously stored name.
Method names are ignored by the default RSA implementation
but can be used by alternative implementations
and by the application program.
.Pp
.Fn RSA_meth_get_flags
retrieves the flags from
.Fa meth .
Flags are documented in
.Xr RSA_test_flags 3 .
.Fn RSA_meth_set_flags
overwrites all flags in
.Fa meth .
Unlike
.Xr RSA_set_flags 3 ,
it does not preserve any flags that were set before the call.
.Pp
.Fn RSA_meth_get0_app_data
and
.Fn RSA_meth_set0_app_data
get and set a pointer to implementation-specific data.
The function
.Fn RSA_meth_free
does not
.Xr free 3
the memory pointed to by
.Fa app_data .
The default RSA implementation does not use
.Fa app_data .
.Pp
.Fn RSA_meth_get_init
and
.Fn RSA_meth_set_init
get and set an optional function used when creating a new
.Vt RSA
object.
Unless
.Fa init
is
.Dv NULL ,
it will be called at the end of
.Xr RSA_new 3 ,
.Xr RSA_new_method 3 ,
and
.Xr RSA_set_method 3 ,
passing a pointer to the newly allocated or reset
.Vt RSA
object as an argument.
The default RSA implementation,
.Xr RSA_PKCS1_SSLeay 3 ,
contains an
.Fa init
function equivalent to calling
.Xr RSA_set_flags 3
with an argument of
.Dv RSA_FLAG_CACHE_PUBLIC | RSA_FLAG_CACHE_PRIVATE .
.Pp
.Fn RSA_meth_get_finish
and
.Fn RSA_meth_set_finish
get and set an optional function for destroying an
.Vt RSA
object.
Unless
.Fa finish
is
.Dv NULL ,
it will be called from
.Xr RSA_set_method 3
and from
.Xr RSA_free 3 .
It takes the same argument as
.Xr RSA_free 3
and is intended to do RSA implementation specific cleanup.
The memory used by the
.Vt RSA
object itself should not be freed by the
.Fa finish
function.
The default RSA implementation contains a
.Fa finish
function freeing the memory used by the
.Dv RSA_FLAG_CACHE_PUBLIC
and
.Dv RSA_FLAG_CACHE_PRIVATE
caches.
.Pp
.Fn RSA_meth_get_pub_enc ,
.Fn RSA_meth_set_pub_enc ,
.Fn RSA_meth_get_pub_dec ,
.Fn RSA_meth_set_pub_dec ,
.Fn RSA_meth_get_priv_enc ,
.Fn RSA_meth_set_priv_enc ,
.Fn RSA_meth_get_priv_dec ,
and
.Fn RSA_meth_set_priv_dec
get and set the mandatory functions
used for public and private key encryption and decryption.
These functions will be called from
.Xr RSA_public_encrypt 3 ,
.Xr RSA_public_decrypt 3 ,
.Xr RSA_private_encrypt 3 ,
and
.Xr RSA_private_decrypt 3 ,
respectively, and take the same parameters as those.
.Pp
.Fn RSA_meth_get_sign ,
.Fn RSA_meth_set_sign ,
.Fn RSA_meth_get_verify ,
and
.Fn RSA_meth_set_verify
get and set the optional functions
used for creating and verifying an RSA signature.
If the flag
.Dv RSA_FLAG_SIGN_VER
is set on the
.Vt RSA
object in question and
.Fa sign
or
.Fa verify
is not
.Dv NULL ,
it will be called from
.Xr RSA_sign 3
or
.Xr RSA_verify 3 ,
respectively, and take the same parameters as those.
Otherwise,
.Xr RSA_private_encrypt 3
or
.Xr RSA_public_decrypt 3
will be used instead.
.Pp
.Fn RSA_meth_get_mod_exp
and
.Fn RSA_meth_set_mod_exp
get and set the function
used for Chinese Remainder Theorem (CRT) computations involving the
.Fa p ,
.Fa q ,
.Fa dmp1 ,
.Fa dmq1 ,
and
.Fa iqmp
fields of an
.Vt RSA
object.
It is used by the default RSA implementation during
.Xr RSA_private_encrypt 3
and
.Xr RSA_private_decrypt 3
when the required components of the private key are available
or when the
.Dv RSA_FLAG_EXT_PKEY
flag is set.
.Pp
.Fn RSA_meth_get_bn_mod_exp
and
.Fn RSA_meth_set_bn_mod_exp
get and set the function used for CRT computations,
specifically the value r =
.Fa a
\(ha
.Fa p
mod
.Fa m .
It is used by the default RSA implementation during
.Xr RSA_public_encrypt 3
and
.Xr RSA_public_decrypt 3
and as a fallback during
.Xr RSA_private_encrypt 3
and
.Xr RSA_private_decrypt 3 .
.Pp
.Fn RSA_meth_get_keygen
and
.Fn RSA_meth_set_keygen
get and set the optional function used for generating a new RSA key pair.
Unless
.Fa keygen
is
.Dv NULL ,
it will be called from
.Xr RSA_generate_key_ex 3
and takes the same parameters.
Otherwise, a builtin default implementation is used.
.Sh RETURN VALUES
.Fn RSA_meth_new
and
.Fn RSA_meth_dup
return the newly allocated
.Vt RSA_METHOD
object or
.Dv NULL
on failure.
.Pp
.Fn RSA_meth_get0_name
returns an internal pointer which must not be freed by the caller.
.Pp
.Fn RSA_meth_get_flags
returns zero or more
.Dv RSA_FLAG_*
constants OR'ed together, or 0 if no flags are set in
.Fa meth .
.Pp
.Fn RSA_meth_get0_app_data
returns the pointer that was earlier passed to
.Fn RSA_meth_set0_app_data
or
.Dv NULL
otherwise.
.Pp
All other
.Fn RSA_meth_get_*
functions return the appropriate function pointer that has been set
with the corresponding
.Fn RSA_meth_set_*
function, or
.Dv NULL
if no such pointer has been set in
.Fa meth .
.Pp
All
.Fn RSA_meth_set*
functions return 1 on success or 0 on failure.
In the current implementation, only
.Fn RSA_meth_set1_name
can actually fail.
.Sh SEE ALSO
.Xr RSA_generate_key_ex 3 ,
.Xr RSA_new 3 ,
.Xr RSA_private_encrypt 3 ,
.Xr RSA_public_encrypt 3 ,
.Xr RSA_set_flags 3 ,
.Xr RSA_set_method 3 ,
.Xr RSA_sign 3
.Sh HISTORY
These functions first appeared in OpenSSL 1.1.0.
.Fn RSA_meth_new ,
.Fn RSA_meth_dup ,
.Fn RSA_meth_free ,
.Fn RSA_meth_set_finish ,
.Fn RSA_meth_set_priv_enc ,
and
.Fn RSA_meth_set_priv_dec
have been available since
.Ox 6.3 ,
.Fn RSA_meth_set1_name
and
.Fn RSA_meth_get_finish
since
.Ox 6.4 ,
and
.Fn RSA_meth_get0_name ,
.Fn RSA_meth_get_flags ,
.Fn RSA_meth_set_flags ,
.Fn RSA_meth_get0_app_data ,
.Fn RSA_meth_set0_app_data ,
.Fn RSA_meth_get_init ,
.Fn RSA_meth_set_init ,
.Fn RSA_meth_set_finish ,
.Fn RSA_meth_get_pub_enc ,
.Fn RSA_meth_set_pub_enc ,
.Fn RSA_meth_get_pub_dec ,
.Fn RSA_meth_set_pub_dec ,
.Fn RSA_meth_get_priv_enc ,
.Fn RSA_meth_get_priv_dec ,
.Fn RSA_meth_get_sign ,
.Fn RSA_meth_set_sign ,
.Fn RSA_meth_get_verify ,
.Fn RSA_meth_set_verify ,
.Fn RSA_meth_get_mod_exp ,
.Fn RSA_meth_set_mod_exp ,
.Fn RSA_meth_get_bn_mod_exp ,
.Fn RSA_meth_set_bn_mod_exp ,
.Fn RSA_meth_get_keygen ,
and
.Fn RSA_meth_set_keygen
since
.Ox 6.6 .