RSA_private_encrypt - low level signature operations
#include <openssl/rsa.h> int RSA_private_encrypt(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding); int RSA_public_decrypt(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding);
OpenSSL RSA_private_encrypt(3openssl)
NAME
RSA_private_encrypt, RSA_public_decrypt - low level signature
operations
SYNOPSIS
#include <openssl/rsa.h>
int RSA_private_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
int RSA_public_decrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
DESCRIPTION
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).
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+--------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+--------------------------+
|Availability | library/security/openssl |
+---------------+--------------------------+
|Stability | Pass-through uncommitted |
+---------------+--------------------------+
SEE ALSO
ERR_get_error(3), rsa(3), RSA_sign(3), RSA_verify(3)
HISTORY
The padding argument was added in SSLeay 0.8. RSA_NO_PADDING is
available since SSLeay 0.9.0.
NOTES
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from
https://www.openssl.org/source/openssl-1.0.2ze.tar.gz.
Further information about this software can be found on the open source
community website at https://www.openssl.org/.
1.0.2ze 2022-05-03
RSA_private_encrypt(3openssl)