RSA_size(3openssl) OpenSSL RSA_size(3openssl)NAME
RSA_size - get RSA modulus size
SYNOPSIS
#include <openssl/rsa.h>
int RSA_size(const RSA *rsa);
DESCRIPTION
This function returns the RSA modulus size in bytes. It can be used to determine how much memory must be allocated for an RSA encrypted
value.
rsa->n must not be NULL.
RETURN VALUE
The size in bytes.
SEE ALSO rsa(3)HISTORY
RSA_size() is available in all versions of SSLeay and OpenSSL.
OpenSSL-0.9.8 Oct 11 2005 RSA_size(3openssl)
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RSA_public_encrypt(3openssl) OpenSSL RSA_public_encrypt(3openssl)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 applica-
tions.
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. Encrypt-
ing 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.
OpenSSL-0.9.8 Oct 11 2005 RSA_public_encrypt(3openssl)