RSA, DSA, DH: Allow some given input to be NULL on already initialised keys

[thirdparty/openssl.git] / doc / crypto / RSA_get0_key.pod

=pod

=head1 NAME

RSA_set0_key, RSA_set0_factors, RSA_set0_crt_params, RSA_get0_key,
RSA_get0_factors, RSA_get0_crt_params, RSA_clear_flags,
RSA_test_flags, RSA_set_flags, RSA_get0_engine - Routines for getting
and setting data in an RSA object

=head1 SYNOPSIS

 #include <openssl/rsa.h>

 int RSA_set0_key(RSA *r, BIGNUM *n, BIGNUM *e, BIGNUM *d);
 int RSA_set0_factors(RSA *r, BIGNUM *p, BIGNUM *q);
 int RSA_set0_crt_params(RSA *r,BIGNUM *dmp1, BIGNUM *dmq1, BIGNUM *iqmp);
 void RSA_get0_key(const RSA *r, BIGNUM **n, BIGNUM **e, BIGNUM **d);
 void RSA_get0_factors(const RSA *r, BIGNUM **p, BIGNUM **q);
 void RSA_get0_crt_params(const RSA *r,
                          BIGNUM **dmp1, BIGNUM **dmq1, BIGNUM **iqmp);
 void RSA_clear_flags(RSA *r, int flags);
 int RSA_test_flags(const RSA *r, int flags);
 void RSA_set_flags(RSA *r, int flags);
 ENGINE *RSA_get0_engine(RSA *r);

=head1 DESCRIPTION

An RSA object contains the components for the public and private key,
B<n>, B<e>, B<d>, B<p>, B<q>, B<dmp1>, B<dmq1> and B<iqmp>.  B<n> is
the modulus common to both public and private key, B<e> is the public
exponent and B<d> is the private exponent.  B<p>, B<q>, B<dmp1>,
B<dmq1> and B<iqmp> are the factors for the second representation of a
private key (see PKCS#1 section 3 Key Types), where B<p> and B<q> are
the first and second factor of B<n> and B<dmp1>, B<dmq1> and B<iqmp>
are the exponents and coefficient for CRT calculations.

The B<n>, B<e> and B<d> parameters can be obtained by calling
RSA_get0_key().  If they have not been set yet, then B<*n>, B<*e> and
B<*d> will be set to NULL.  Otherwise, they are set to pointers to
their respective values. These point directly to the internal
representations of the values and therefore should not be freed
by the caller.

The B<n>, B<e> and B<d> parameter values can be set by calling
RSA_set0_key() and passing the new values for B<n>, B<e> and B<d> as
parameters to the function. Calling this function transfers the memory
management of the values to the RSA object, and therefore the values
that have been passed in should not be freed by the caller after this
function has been called.

In a similar fashion, the B<p> and B<q> parameters can be obtained and
set with RSA_get0_factors() and RSA_set0_factors(), and the B<dmp1>,
B<dmq1> and B<iqmp> parameters can be obtained and set with
RSA_get0_crt_params() and RSA_set0_crt_params().

RSA_set_flags() sets the flags in the B<flags> parameter on the RSA
object. Multiple flags can be passed in one go (bitwise ORed together).
Any flags that are already set are left set. RSA_test_flags() tests to
see whether the flags passed in the B<flags> parameter are currently
set in the RSA object. Multiple flags can be tested in one go. All
flags that are currently set are returned, or zero if none of the
flags are set. RSA_clear_flags() clears the specified flags within the
RSA object.

RSA_get0_engine() returns a handle to the ENGINE that has been set for
this RSA object, or NULL if no such ENGINE has been set.

=head1 RETURN VALUES

RSA_set0_key(), RSA_set0_factors and RSA_set0_crt_params() return 1 on
success or 0 on failure.

RSA_test_flags() returns the current state of the flags in the RSA object.

RSA_get0_engine() returns the ENGINE set for the RSA object or NULL if no
ENGINE has been set.

=head1 SEE ALSO

L<rsa(3)>, L<RSA_new(3)>, L<RSA_size(3)>

=head1 HISTORY

The functions described here were added in OpenSSL version 1.1.0.

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