.\" $OpenBSD: RSA_pkey_ctx_ctrl.3,v 1.7 2023/05/05 12:22:21 tb Exp $ .\" full merge up to: .\" OpenSSL man3/EVP_PKEY_CTX_ctrl.pod 99d63d46 Oct 26 13:56:48 2016 -0400 .\" OpenSSL man3/EVP_PKEY_CTX_set_rsa_pss_keygen_md.pod .\" 87103969 Oct 1 14:11:57 2018 -0700 .\" selective merge up to: .\" OpenSSL man3/EVP_PKEY_CTX_ctrl.pod df75c2b f Dec 9 01:02:36 2018 +0100 .\" .\" This file was written by Dr. Stephen Henson .\" and Antoine Salon . .\" Copyright (c) 2006, 2009, 2013, 2014, 2015, 2017, 2018 The OpenSSL Project. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. All advertising materials mentioning features or use of this .\" software must display the following acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" .\" .\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to .\" endorse or promote products derived from this software without .\" prior written permission. For written permission, please contact .\" openssl-core@openssl.org. .\" .\" 5. Products derived from this software may not be called "OpenSSL" .\" nor may "OpenSSL" appear in their names without prior written .\" permission of the OpenSSL Project. .\" .\" 6. Redistributions of any form whatsoever must retain the following .\" acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" .\" .\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY .\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. 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: May 5 2023 $ .Dt RSA_PKEY_CTX_CTRL 3 .Os .Sh NAME .Nm RSA_pkey_ctx_ctrl , .Nm EVP_PKEY_CTX_set_rsa_padding , .Nm EVP_PKEY_CTX_get_rsa_padding , .Nm EVP_PKEY_CTX_set_rsa_keygen_bits , .Nm EVP_PKEY_CTX_set_rsa_keygen_pubexp , .Nm EVP_PKEY_CTX_set_rsa_mgf1_md , .Nm EVP_PKEY_CTX_get_rsa_mgf1_md , .Nm EVP_PKEY_CTX_set_rsa_oaep_md , .Nm EVP_PKEY_CTX_get_rsa_oaep_md , .Nm EVP_PKEY_CTX_set0_rsa_oaep_label , .Nm EVP_PKEY_CTX_get0_rsa_oaep_label , .Nm EVP_PKEY_CTX_set_rsa_pss_saltlen , .Nm EVP_PKEY_CTX_get_rsa_pss_saltlen , .Nm EVP_PKEY_CTX_set_rsa_pss_keygen_md , .Nm EVP_PKEY_CTX_set_rsa_pss_keygen_mgf1_md , .Nm EVP_PKEY_CTX_set_rsa_pss_keygen_saltlen .Nd RSA private key control operations .Sh SYNOPSIS .In openssl/rsa.h .Ft int .Fo RSA_pkey_ctx_ctrl .Fa "EVP_PKEY_CTX *ctx" .Fa "int optype" .Fa "int cmd" .Fa "int p1" .Fa "void *p2" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_padding .Fa "EVP_PKEY_CTX *ctx" .Fa "int pad" .Fc .Ft int .Fo EVP_PKEY_CTX_get_rsa_padding .Fa "EVP_PKEY_CTX *ctx" .Fa "int *ppad" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_keygen_bits .Fa "EVP_PKEY_CTX *ctx" .Fa "int mbits" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_keygen_pubexp .Fa "EVP_PKEY_CTX *ctx" .Fa "BIGNUM *pubexp" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_mgf1_md .Fa "EVP_PKEY_CTX *ctx" .Fa "const EVP_MD *md" .Fc .Ft int .Fo EVP_PKEY_CTX_get_rsa_mgf1_md .Fa "EVP_PKEY_CTX *ctx" .Fa "const EVP_MD **pmd" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_oaep_md .Fa "EVP_PKEY_CTX *ctx" .Fa "const EVP_MD *md" .Fc .Ft int .Fo EVP_PKEY_CTX_get_rsa_oaep_md .Fa "EVP_PKEY_CTX *ctx" .Fa "const EVP_MD **pmd" .Fc .Ft int .Fo EVP_PKEY_CTX_set0_rsa_oaep_label .Fa "EVP_PKEY_CTX *ctx" .Fa "unsigned char *label" .Fa "int len" .Fc .Ft int .Fo EVP_PKEY_CTX_get0_rsa_oaep_label .Fa "EVP_PKEY_CTX *ctx" .Fa "unsigned char **plabel" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_pss_saltlen .Fa "EVP_PKEY_CTX *ctx" .Fa "int len" .Fc .Ft int .Fo EVP_PKEY_CTX_get_rsa_pss_saltlen .Fa "EVP_PKEY_CTX *ctx" .Fa "int *plen" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_pss_keygen_md .Fa "EVP_PKEY_CTX *pctx" .Fa "const EVP_MD *md" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_pss_keygen_mgf1_md .Fa "EVP_PKEY_CTX *pctx" .Fa "const EVP_MD *md" .Fc .Ft int .Fo EVP_PKEY_CTX_set_rsa_pss_keygen_saltlen .Fa "EVP_PKEY_CTX *pctx" .Fa "int saltlen" .Fc .Sh DESCRIPTION The function .Fn RSA_pkey_ctx_ctrl is a shallow wrapper around .Xr EVP_PKEY_CTX_ctrl 3 which only succeeds if .Fa ctx matches either .Dv EVP_PKEY_RSA or .Dv EVP_PKEY_RSA_PSS . .Pp All the remaining "functions" are implemented as macros. .Pp The .Fn EVP_PKEY_CTX_set_rsa_padding macro sets the RSA padding mode for .Fa ctx . The .Fa pad parameter can take the value .Dv RSA_PKCS1_PADDING for PKCS#1 padding, .Dv RSA_NO_PADDING for no padding, .Dv RSA_PKCS1_OAEP_PADDING for OAEP padding (encrypt and decrypt only), .Dv RSA_X931_PADDING for X9.31 padding (signature operations only) and .Dv RSA_PKCS1_PSS_PADDING (sign and verify only). Only the last one can be used with keys of the type .Dv EVP_PKEY_RSA_PSS . .Pp Two RSA padding modes behave differently if .Xr EVP_PKEY_CTX_set_signature_md 3 is used. If this macro is called for PKCS#1 padding, the plaintext buffer is an actual digest value and is encapsulated in a .Vt DigestInfo structure according to PKCS#1 when signing and this structure is expected (and stripped off) when verifying. If this control is not used with RSA and PKCS#1 padding then the supplied data is used directly and not encapsulated. In the case of X9.31 padding for RSA the algorithm identifier byte is added or checked and removed if this control is called. If it is not called then the first byte of the plaintext buffer is expected to be the algorithm identifier byte. .Pp The .Fn EVP_PKEY_CTX_get_rsa_padding macro retrieves the RSA padding mode for .Fa ctx . .Pp The .Fn EVP_PKEY_CTX_set_rsa_keygen_bits macro sets the RSA key length for RSA or RSA-PSS key generation to .Fa mbits . The smallest supported value is 512 bits. If not specified, 1024 bits is used. .Pp The .Fn EVP_PKEY_CTX_set_rsa_keygen_pubexp macro sets the public exponent value for RSA or RSA-PSS key generation to .Fa pubexp . Currently, it should be an odd integer. The .Fa pubexp pointer is used internally by this function, so it should not be modified or freed after the call. If this macro is not called, then 65537 is used. .Pp The .Fn EVP_PKEY_CTX_set_rsa_mgf1_md macro sets the MGF1 digest for RSA padding schemes to .Fa md . Unless explicitly specified, the signing digest is used. The padding mode must have been set to .Dv RSA_PKCS1_OAEP_PADDING or .Dv RSA_PKCS1_PSS_PADDING . If the key is of the type .Dv EVP_PKEY_RSA_PSS and has usage restrictions, an error occurs if an attempt is made to set the digest to anything other than the restricted value. .Pp The .Fn EVP_PKEY_CTX_get_rsa_mgf1_md macro retrieves the MGF1 digest for .Fa ctx . Unless explicitly specified, the signing digest is used. The padding mode must have been set to .Dv RSA_PKCS1_OAEP_PADDING or .Dv RSA_PKCS1_PSS_PADDING . .Ss Optimal asymmetric encryption padding The following macros require that the padding mode was set to .Dv RSA_PKCS1_OAEP_PADDING . .Pp The .Fn EVP_PKEY_CTX_set_rsa_oaep_md macro sets the message digest type used in RSA OAEP to .Fa md . .Pp The .Fn EVP_PKEY_CTX_get_rsa_oaep_md macro gets the message digest type used in RSA OAEP to .Pf * Fa pmd . .Pp The .Fn EVP_PKEY_CTX_set0_rsa_oaep_label macro sets the RSA OAEP label to .Fa label and its length to .Fa len . If .Fa label is .Dv NULL or .Fa len is 0, the label is cleared. The library takes ownership of the label so the caller should not free the original memory pointed to by .Fa label . .Pp The .Fn EVP_PKEY_CTX_get0_rsa_oaep_label macro gets the RSA OAEP label to .Pf * Fa plabel . The return value is the label length. The resulting pointer is owned by the library and should not be freed by the caller. .Ss Probabilistic signature scheme The following macros require that the padding mode was set to .Dv RSA_PKCS1_PSS_PADDING . .Pp The .Fn EVP_PKEY_CTX_set_rsa_pss_saltlen macro sets the RSA PSS salt length to .Fa len . Three special values are supported: .Dv RSA_PSS_SALTLEN_DIGEST sets the salt length to the digest length. .Dv RSA_PSS_SALTLEN_MAX sets the salt length to the maximum permissible value. When signing, .Dv RSA_PSS_SALTLEN_AUTO sets the salt length to the maximum permissible value. When verifying, .Dv RSA_PSS_SALTLEN_AUTO causes the salt length to be automatically determined based on the PSS block structure. If this macro is not called, a salt length value of .Dv RSA_PSS_SALTLEN_AUTO is used by default. .Pp If the key has usage restrictions and an attempt is made to set the salt length below the minimum value, an error occurs. Also, if the key has usage restrictions, .Dv RSA_PSS_SALTLEN_AUTO is not supported for verification. .Pp The .Fn EVP_PKEY_CTX_get_rsa_pss_saltlen macro retrieves the RSA PSS salt length for .Fa ctx . .Pp Optional parameter restrictions can be specified when generating a PSS key. If any restrictions are set using the macros described below, then all parameters are restricted. For example, setting a minimum salt length also restricts the digest and MGF1 algorithms. If any restrictions are in place, then they are reflected in the corresponding parameters of the public key when (for example) a certificate request is signed. .Pp .Fn EVP_PKEY_CTX_set_rsa_pss_keygen_md restricts the digest algorithm the generated key can use to .Fa md . .Pp .Fn EVP_PKEY_CTX_set_rsa_pss_keygen_mgf1_md restricts the MGF1 algorithm the generated key can use to .Fa md . .Pp .Fn EVP_PKEY_CTX_set_rsa_pss_keygen_saltlen restricts the minimum salt length to .Fa saltlen . .Sh RETURN VALUES These functions return a positive value for success or 0 or a negative value for failure. In particular, a return value of -2 indicates the operation is not supported by the public key algorithm. .Sh SEE ALSO .Xr EVP_DigestInit 3 , .Xr EVP_PKEY_CTX_ctrl 3 , .Xr EVP_PKEY_CTX_new 3 , .Xr EVP_PKEY_decrypt 3 , .Xr EVP_PKEY_derive 3 , .Xr EVP_PKEY_encrypt 3 , .Xr EVP_PKEY_get_default_digest_nid 3 , .Xr EVP_PKEY_keygen 3 , .Xr EVP_PKEY_meth_set_ctrl 3 , .Xr EVP_PKEY_sign 3 , .Xr EVP_PKEY_verify 3 , .Xr EVP_PKEY_verify_recover 3 .Sh HISTORY The functions .Fn EVP_PKEY_CTX_set_rsa_padding , .Fn EVP_PKEY_CTX_set_rsa_keygen_bits , .Fn EVP_PKEY_CTX_set_rsa_keygen_pubexp , and .Fn EVP_PKEY_CTX_set_rsa_pss_saltlen first appeared in OpenSSL 1.0.0 and have been available since .Ox 4.9 . .Pp The functions .Fn EVP_PKEY_CTX_get_rsa_padding , .Fn EVP_PKEY_CTX_set_rsa_mgf1_md , .Fn EVP_PKEY_CTX_get_rsa_mgf1_md , and .Fn EVP_PKEY_CTX_get_rsa_pss_saltlen first appeared in OpenSSL 1.0.1 and have been available since .Ox 5.3 . .Pp The functions .Fn EVP_PKEY_CTX_set_rsa_oaep_md , .Fn EVP_PKEY_CTX_get_rsa_oaep_md , .Fn EVP_PKEY_CTX_set0_rsa_oaep_label , and .Fn EVP_PKEY_CTX_get0_rsa_oaep_label first appeared in OpenSSL 1.0.2 and have been available since .Ox 6.7 . .Pp The function .Fn RSA_pkey_ctx_ctrl first appeared in OpenSSL 1.1.1 and has been available since .Ox 6.7 .