/usr/man/cat.3/RSA_public_encrypt.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_private_decrypt(3)