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.Dd $Mdocdate: July 13 2019 $
.Dt RSA_GET0_KEY 3
.Os
.Sh NAME
.Nm RSA_get0_key ,
.Nm RSA_set0_key ,
.Nm RSA_get0_factors ,
.Nm RSA_set0_factors ,
.Nm RSA_get0_crt_params ,
.Nm RSA_set0_crt_params ,
.Nm RSA_clear_flags ,
.Nm RSA_test_flags ,
.Nm RSA_set_flags
.Nd get and set data in an RSA object
.Sh SYNOPSIS
.In openssl/rsa.h
.Ft void
.Fo RSA_get0_key
.Fa "const RSA *r"
.Fa "const BIGNUM **n"
.Fa "const BIGNUM **e"
.Fa "const BIGNUM **d"
.Fc
.Ft int
.Fo RSA_set0_key
.Fa "RSA *r"
.Fa "BIGNUM *n"
.Fa "BIGNUM *e"
.Fa "BIGNUM *d"
.Fc
.Ft void
.Fo RSA_get0_factors
.Fa "const RSA *r"
.Fa "const BIGNUM **p"
.Fa "const BIGNUM **q"
.Fc
.Ft int
.Fo RSA_set0_factors
.Fa "RSA *r"
.Fa "BIGNUM *p"
.Fa "BIGNUM *q"
.Fc
.Ft void
.Fo RSA_get0_crt_params
.Fa "const RSA *r"
.Fa "const BIGNUM **dmp1"
.Fa "const BIGNUM **dmq1"
.Fa "const BIGNUM **iqmp"
.Fc
.Ft int
.Fo RSA_set0_crt_params
.Fa "RSA *r"
.Fa "BIGNUM *dmp1"
.Fa "BIGNUM *dmq1"
.Fa "BIGNUM *iqmp"
.Fc
.Ft void
.Fo RSA_clear_flags
.Fa "RSA *r"
.Fa "int flags"
.Fc
.Ft int
.Fo RSA_test_flags
.Fa "const RSA *r"
.Fa "int flags"
.Fc
.Ft void
.Fo RSA_set_flags
.Fa "RSA *r"
.Fa "int flags"
.Fc
.Sh DESCRIPTION
An
.Vt RSA
object contains the components for the public and private key.
.Fa n
is the modulus common to both public and private key,
.Fa e
is the public exponent and
.Fa d
is the private exponent.
.Fa p ,
.Fa q ,
.Fa dmp1 ,
.Fa dmq1 ,
and
.Fa iqmp
are the factors for the second representation of a private key
(see PKCS#1 section 3 Key Types), where
.Fa p
and
.Fa q
are the first and second factor of
.Fa n .
.Fa dmp1 ,
.Fa dmq1 ,
and
.Fa iqmp
are the exponents and coefficient
for Chinese Remainder Theorem (CRT) calculations.
.Pp
The
.Fa n ,
.Fa e ,
and
.Fa d
parameters can be obtained by calling
.Fn RSA_get0_key .
If they have not been set yet, then
.Pf * Fa n ,
.Pf * Fa e ,
and
.Pf * Fa d
are set to
.Dv NULL .
Otherwise, they are set to pointers to the internal representations
of the values that should not be freed by the caller.
.Pp
The
.Fa n ,
.Fa e ,
and
.Fa d
parameter values can be set by calling
.Fn RSA_set0_key .
The values
.Fa n
and
.Fa e
must be
.Pf non- Dv NULL
the first time this function is called on a given
.Vt RSA
object.
The value
.Fa d
may be
.Dv NULL .
On subsequent calls, any of these values may be
.Dv NULL ,
which means that the corresponding field is left untouched.
Calling this function transfers the memory management of the values to
the RSA object.
Therefore, the values that have been passed in
should not be freed by the caller.
.Pp
In a similar fashion, the
.Fa p
and
.Fa q
parameters can be obtained and set with
.Fn RSA_get0_factors
and
.Fn RSA_set0_factors ,
and the
.Fa dmp1 ,
.Fa dmq1 ,
and
.Fa iqmp
parameters can be obtained and set with
.Fn RSA_get0_crt_params
and
.Fn RSA_set0_crt_params .
.Pp
For
.Fn RSA_get0_key ,
.Fn RSA_get0_factors ,
and
.Fn RSA_get0_crt_params ,
.Dv NULL
value
.Vt BIGNUM **
output arguments are permitted.
The functions
ignore
.Dv NULL
arguments but return values for other,
.Pf non- Dv NULL ,
arguments.
.Pp
Values retrieved with
.Fn RSA_get0_key ,
.Fn RSA_get0_factors ,
and
.Fn RSA_get0_crt_params
are owned by the
.Vt RSA
object used in the call and may therefore
.Em not
be passed to
.Fn RSA_set0_key ,
.Fn RSA_set0_factors ,
or
.Fn RSA_set0_crt_params .
If needed, duplicate the received value using
.Xr BN_dup 3
and pass the duplicate.
.Pp
.Fn RSA_clear_flags
clears the specified
.Fa flags
in
.Fa r .
.Fn RSA_test_flags
tests the
.Fa flags
in
.Fa r .
.Fn RSA_set_flags
sets the
.Fa flags
in
.Fa r ;
any flags already set remain set.
For all three functions, multiple flags can be passed in one call,
OR'ed together bitwise.
.Pp
The following flags are supported:
.Bl -tag -width Ds
.It Dv RSA_FLAG_CACHE_PRIVATE No and Dv RSA_FLAG_CACHE_PUBLIC
Precompute information needed for Montgomery multiplication
from the private and public key, respectively, and cache it in
.Fa r
for repeated use.
These two flags are set by default for the default RSA implementation,
.Xr RSA_PKCS1_SSLeay 3 .
.It Dv RSA_FLAG_EXT_PKEY
The function set with
.Xr RSA_meth_set_mod_exp 3
is used for private key operations even if
.Fa p ,
.Fa q ,
.Fa dmp1 ,
.Fa dmq1 ,
and
.Fa iqmp
are all
.Dv NULL .
This flag may be useful with RSA implementations that do not use the
private key components stored in the standard fields, for example
because they store the private key in external hardware.
If this flag is unset, the function set with
.Xr RSA_meth_set_bn_mod_exp 3
is used with
.Fa n
and
.Fa d
instead.
.It Dv RSA_FLAG_NO_BLINDING
Turn off blinding during private key encryption and decryption.
This flag is set by
.Xr RSA_blinding_off 3 .
.It Dv RSA_FLAG_SIGN_VER
Enable the use of the functions set with
.Xr RSA_meth_set_sign 3
and
.Xr RSA_meth_set_verify 3 .
If unset, the functions set with
.Xr RSA_meth_set_priv_enc 3
and
.Xr RSA_meth_set_pub_dec 3
are used instead, respectively.
.El
.Pp
The flags
.Dv RSA_FLAG_BLINDING ,
.Dv RSA_FLAG_CHECKED ,
.Dv RSA_FLAG_FIPS_METHOD ,
.Dv RSA_FLAG_NON_FIPS_ALLOW ,
and
.Dv RSA_FLAG_THREAD_SAFE
are defined for compatibility with existing code but have no effect.
.Sh RETURN VALUES
.Fn RSA_set0_key ,
.Fn RSA_set0_factors ,
and
.Fn RSA_set0_crt_params
return 1 on success or 0 on failure.
.Pp
.Fn RSA_test_flags
returns those of the given
.Fa flags
currently set in
.Fa r
or 0 if none of the given
.Fa flags
are set.
.Sh SEE ALSO
.Xr RSA_check_key 3 ,
.Xr RSA_generate_key 3 ,
.Xr RSA_new 3 ,
.Xr RSA_print 3 ,
.Xr RSA_size 3
.Sh HISTORY
These functions first appeared in OpenSSL 1.1.0
and have been available since
.Ox 6.3 .