.\" $OpenBSD: RSA_new.3,v 1.17 2022/07/13 21:51:35 schwarze Exp $ .\" full merge up to: .\" OpenSSL doc/man3/RSA_new.pod e9b77246 Jan 20 19:58:49 2017 +0100 .\" OpenSSL doc/crypto/rsa.pod 35d2e327 Jun 3 16:19:49 2016 -0400 (final) .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2018, 2019 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. 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IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: July 13 2022 $ .Dt RSA_NEW 3 .Os .Sh NAME .Nm RSA_new , .Nm RSAPrivateKey_dup , .Nm RSAPublicKey_dup , .Nm RSA_up_ref , .Nm RSA_free .Nd allocate and free RSA objects .Sh SYNOPSIS .In openssl/rsa.h .Ft RSA * .Fn RSA_new void .Ft RSA * .Fo RSAPrivateKey_dup .Fa "RSA *rsa" .Fc .Ft RSA * .Fo RSAPublicKey_dup .Fa "RSA *rsa" .Fc .Ft int .Fo RSA_up_ref .Fa "RSA *rsa" .Fc .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, setting the reference count to 1. It is equivalent to calling .Xr RSA_new_method 3 with a .Dv NULL argument. .Pp .Fn RSAPrivateKey_dup calls .Fn RSA_new and copies the public and private key components from .Fa rsa into the new structure. .Fn RSAPublicKey_dup does the same except that it copies the public key components only. .Pp .Fn RSA_up_ref increments the reference count by 1. .Pp .Fn RSA_free decrements the reference count by 1. If it reaches 0, it calls the optional .Fa finish function set up with .Xr RSA_meth_set_finish 3 , calls .Xr ENGINE_finish 3 if .Fa rsa uses an engine, and 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 .Fn RSA_new , .Fn RSAPrivateKey_dup , and .Fn RSAPublicKey_dup return a pointer to the newly allocated structure, or .Dv NULL if an error occurs. An error code can be obtained by .Xr ERR_get_error 3 . .Pp .Fn RSA_up_ref returns 1 for success or 0 for failure. .Sh SEE ALSO .Xr BN_new 3 , .Xr crypto 3 , .Xr d2i_RSAPublicKey 3 , .Xr DH_new 3 , .Xr DSA_new 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_pkey_ctx_ctrl 3 , .Xr RSA_print 3 , .Xr RSA_private_encrypt 3 , .Xr RSA_PSS_PARAMS_new 3 , .Xr RSA_public_encrypt 3 , .Xr RSA_security_bits 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. .Fn RSAPrivateKey_dup first appeared in SSLeay 0.5.1 and .Fn RSAPublicKey_dup in SSLeay 0.5.2. These functions have been available since .Ox 2.4 . .Pp .Fn RSA_up_ref first appeared in OpenSSL 0.9.7 and has been available since .Ox 3.2 .