NAME

       RSA_private_encrypt, RSA_public_decrypt - low-level signature operations

SYNOPSIS

        #include <openssl/rsa.h>

       The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely
       by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

        int RSA_private_encrypt(int flen, unsigned char *from,
                                unsigned char *to, RSA *rsa, int padding);

        int RSA_public_decrypt(int flen, unsigned char *from,
                               unsigned char *to, RSA *rsa, int padding);

DESCRIPTION

       Both of the functions described on this page are deprecated.  Applications should instead
       use EVP_PKEY_sign_init_ex(3), EVP_PKEY_sign(3), EVP_PKEY_verify_recover_init(3), and
       EVP_PKEY_verify_recover(3).

       These functions handle RSA signatures at a low-level.

       RSA_private_encrypt() signs the flen bytes at from (usually a message digest with an
       algorithm identifier) using the private key rsa and stores the signature in to. to must
       point to RSA_size(rsa) bytes of memory.

       padding denotes one of the following modes:

       RSA_PKCS1_PADDING
           PKCS #1 v1.5 padding. This function does not handle the algorithmIdentifier specified
           in PKCS #1. When generating or verifying PKCS #1 signatures, RSA_sign(3) and
           RSA_verify(3) should be used.

       RSA_NO_PADDING
           Raw RSA signature. This mode should only be used to implement cryptographically sound
           padding modes in the application code.  Signing user data directly with RSA is
           insecure.

       RSA_public_decrypt() recovers the message digest from the flen bytes long signature at
       from using the signer's public key rsa. to must point to a memory section large enough to
       hold the message digest (which is smaller than RSA_size(rsa) - 11). padding is the padding
       mode that was used to sign the data.

RETURN VALUES

       RSA_private_encrypt() returns the size of the signature (i.e., RSA_size(rsa)).
       RSA_public_decrypt() returns the size of the recovered message digest.

       On error, -1 is returned; the error codes can be obtained by ERR_get_error(3).

SEE ALSO

       ERR_get_error(3), RSA_sign(3), RSA_verify(3), EVP_PKEY_sign(3), EVP_PKEY_verify_recover(3)

HISTORY

       Both of these functions were deprecated in OpenSSL 3.0.

COPYRIGHT

       Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except
       in compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.