rsa_public_encrypt(3) - Linux man page
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, 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.