NAME
RSA_public_encrypt, RSA_private_decrypt — RSA public key cryptography
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
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, and less than RSA_size(rsa)
- 41 for RSA_PKCS1_OAEP_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.
