

 
Manual Reference Pages  RSA_PRIVATE_DECRYPT (3)
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NAME
RSA_public_encrypt, RSA_private_decrypt  RSA public key cryptography
CONTENTS
SYNOPSIS
#include <openssl/rsa.h>
int RSA_public_encrypt(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
int RSA_private_decrypt(int flen, 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

EMEOAEP as defined in PKCS #1 v2.0 with SHA1, MGF1 and an empty
encoding parameter. This mode is recommended for all new applications.

RSA_SSLV23_PADDING

PKCS #1 v1.5 padding with an SSLspecific 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.
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).
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.
1.0.1s  RSA_PUBLIC_ENCRYPT (3)  20160301 
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