$NetBSD: RSA_private_encrypt.3,v 1.25 2024/09/08 13:08:29 christos Exp $

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Title "RSA_private_encrypt 3" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
RSA_private_encrypt, RSA_public_decrypt - low-level signature operations Header "SYNOPSIS" .Vb 1 #include <openssl/rsa.h> .Ve

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):

.Vb 2 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); .Ve

Header "DESCRIPTION" Both of the functions described on this page are deprecated. Applications should instead use EVP_PKEY_sign_init_ex\|(3), \fBEVP_PKEY_sign\|(3), EVP_PKEY_verify_recover_init\|(3), and \fBEVP_PKEY_verify_recover\|(3).

These functions handle RSA signatures at a low-level.

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

\fBpadding denotes one of the following modes:

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

\fBRSA_public_decrypt() recovers the message digest from the flen bytes long signature at from using the signer's public key \fBrsa. 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.

Header "RETURN VALUES" \fBRSA_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).

Header "SEE ALSO" \fBERR_get_error\|(3), \fBRSA_sign\|(3), RSA_verify\|(3), \fBEVP_PKEY_sign\|(3), EVP_PKEY_verify_recover\|(3) Header "HISTORY" Both of these functions were deprecated in OpenSSL 3.0. Header "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>.