.\"	$OpenBSD: RSA_new.3,v 1.9 2018/04/03 21:20:49 tb Exp $
.\"	OpenSSL doc/man3/RSA_new.pod 99d63d46 Oct 26 13:56:48 2016 -0400
.\"	OpenSSL doc/crypto/rsa.pod 35d2e327 Jun 3 16:19:49 2016 -0400
.\"
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.Dd $Mdocdate: April 3 2018 $
.Dt RSA_NEW 3
.Os
.Sh NAME
.Nm RSA_new ,
.Nm RSA_free
.Nd allocate and free RSA objects
.Sh SYNOPSIS
.In openssl/rsa.h
.Ft RSA *
.Fn RSA_new void
.Ft void
.Fo RSA_free
.Fa "RSA *rsa"
.Fc
.Sh DESCRIPTION
The RSA functions implement RSA public key encryption and signatures
as defined in PKCS #1 v2.0 (RFC 2437).
.Pp
.Fn RSA_new
allocates and initializes an
.Vt RSA
structure.
It is equivalent to calling
.Fn RSA_new_method NULL .
.Pp
.Fn RSA_free
frees the
.Vt RSA
structure and its components.
The key is erased before the memory is returned to the system.
If
.Fa rsa
is a
.Dv NULL
pointer, no action occurs.
.Pp
The
.Vt RSA
structure consists of several
.Vt BIGNUM
components.
It can contain public as well as private RSA keys:
.Bd -literal
typedef struct {
	BIGNUM *n;		// public modulus
	BIGNUM *e;		// public exponent
	BIGNUM *d;		// private exponent
	BIGNUM *p;		// secret prime factor
	BIGNUM *q;		// secret prime factor
	BIGNUM *dmp1;		// d mod (p-1)
	BIGNUM *dmq1;		// d mod (q-1)
	BIGNUM *iqmp;		// q^-1 mod p
	// ...
} RSA;
.Ed
.Pp
In public keys, the private exponent
.Fa d
and the related secret values
.Fa p , q , dmp1 , dmp2 ,
and
.Fa iqmp
are
.Dv NULL .
.Pp
.Fa p ,
.Fa q ,
.Fa dmp1 ,
.Fa dmq1 ,
and
.Fa iqmp
may be
.Dv NULL
in private keys, but the RSA operations are much faster when these
values are available.
.Pp
Note that RSA keys may use non-standard
.Vt RSA_METHOD
implementations, either directly or by the use of
.Vt ENGINE
modules.
In some cases (e.g. an
.Vt ENGINE
providing support for hardware-embedded keys), these
.Vt BIGNUM
values will not be used by the implementation or may be used for
alternative data storage.
For this reason, applications should generally avoid using
.Vt RSA
structure elements directly and instead use API functions to query
or modify keys.
.Sh RETURN VALUES
If the allocation fails,
.Fn RSA_new
returns
.Dv NULL
and sets an error code that can be obtained by
.Xr ERR_get_error 3 .
Otherwise it returns a pointer to the newly allocated structure.
.Sh SEE ALSO
.Xr BN_new 3 ,
.Xr d2i_RSAPublicKey 3 ,
.Xr DH_new 3 ,
.Xr DSA_new 3 ,
.Xr engine 3 ,
.Xr ERR_get_error 3 ,
.Xr EVP_PKEY_set1_RSA 3 ,
.Xr RSA_blinding_on 3 ,
.Xr RSA_check_key 3 ,
.Xr RSA_generate_key 3 ,
.Xr RSA_get0_key 3 ,
.Xr RSA_get_ex_new_index 3 ,
.Xr RSA_meth_new 3 ,
.Xr RSA_padding_add_PKCS1_type_1 3 ,
.Xr RSA_print 3 ,
.Xr RSA_private_encrypt 3 ,
.Xr RSA_public_encrypt 3 ,
.Xr RSA_set_method 3 ,
.Xr RSA_sign 3 ,
.Xr RSA_sign_ASN1_OCTET_STRING 3 ,
.Xr RSA_size 3
.Sh STANDARDS
SSL, PKCS #1 v2.0
.Pp
RSA was covered by a US patent which expired in September 2000.
.Sh HISTORY
.Fn RSA_new
and
.Fn RSA_free
appeared in SSLeay 0.4 or earlier and have been available since
.Ox 2.4 .