/usr/man/cat.3/RSA_private_decrypt.3
RSA_public_encrypt(3) OpenSSL RSA_public_encrypt(3)
NAME
RSA_public_encrypt, RSA_private_decrypt - RSA public key
cryptography
SYNOPSIS
#include <openssl/rsa.h>
int RSA_public_encrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
int RSA_private_decrypt(int flen, const unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
DESCRIPTION
RSA_public_encrypt() encrypts the flen bytes at from
(usually a session key) using the public key rsa and stores
the ciphertext 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 currently is the most widely
used mode.
RSA_PKCS1_OAEP_PADDING
EME-OAEP as defined in PKCS #1 v2.0 with SHA-1, MGF1 and
an empty encoding parameter. This mode is recommended
for all new applications.
RSA_SSLV23_PADDING
PKCS #1 v1.5 padding with an SSL-specific modification
that denotes that the server is SSL3 capable.
RSA_NO_PADDING
Raw RSA encryption. This mode should only be used to
implement cryptographically sound padding modes in the
application code. Encrypting user data directly with
RSA is insecure.
flen must be less than RSA_size(rsa) - 11 for the PKCS #1
v1.5 based padding modes, less than RSA_size(rsa) - 41 for
RSA_PKCS1_OAEP_PADDING and exactly RSA_size(rsa) for
RSA_NO_PADDING. The random number generator must be seeded
prior to calling RSA_public_encrypt().
RSA_private_decrypt() decrypts the flen bytes at from using
the private key rsa and stores the plaintext in to. to must
point to a memory section large enough to hold the decrypted
data (which is smaller than RSA_size(rsa)). padding is the
padding mode that was used to encrypt the data.
1.0.2t Last change: 2019-09-10 1
RSA_public_encrypt(3) OpenSSL RSA_public_encrypt(3)
RETURN VALUES
RSA_public_encrypt() returns the size of the encrypted data
(i.e., RSA_size(rsa)). RSA_private_decrypt() returns the
size of the recovered plaintext.
On error, -1 is returned; the error codes can be obtained by
ERR_get_error(3).
WARNING
Decryption failures in the RSA_PKCS1_PADDING mode leak
information which can potentially be used to mount a
Bleichenbacher padding oracle attack. This is an inherent
weakness in the PKCS #1 v1.5 padding design. Prefer
RSA_PKCS1_OAEP_PADDING.
CONFORMING TO
SSL, PKCS #1 v2.0
SEE ALSO
ERR_get_error(3), rand(3), rsa(3), RSA_size(3)
HISTORY
The padding argument was added in SSLeay 0.8. RSA_NO_PADDING
is available since SSLeay 0.9.0, OAEP was added in OpenSSL
0.9.2b.
1.0.2t Last change: 2019-09-10 2
See also RSA_public_encrypt(3)
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