The returned ciphertext in to will always be zero padded to exactly RSA_size( rsa) bytes. When a padding mode other than RSA_NO_PADDING is in use, then RSA_public_encrypt() will include some random bytes into the ciphertext and therefore the ciphertext will be different each time, even if the plaintext and the public key are exactly identical. Encrypting user data directly with RSA is insecure.įlen must not be more than RSA_size( rsa) - 11 for the PKCS #1 v1.5 based padding modes, not more than RSA_size( rsa) - 42 for RSA_PKCS1_OAEP_PADDING and exactly RSA_size( rsa) for RSA_NO_PADDING. This mode should only be used to implement cryptographically sound padding modes in the application code. This mode is recommended for all new applications. SEE WARNING BELOW.ĮME-OAEP as defined in PKCS #1 v2.0 with SHA-1, MGF1 and an empty encoding parameter. However, it is highly recommended to use RSA_PKCS1_OAEP_PADDING in new applications. This currently is the most widely used mode. Padding denotes one of the following modes: to must point to RSA_size( rsa) bytes of memory. RSA_public_encrypt() encrypts the flen bytes at from (usually a session key) using the public key rsa and stores the ciphertext in to. Applications should instead use EVP_PKEY_encrypt_init_ex(3), EVP_PKEY_encrypt(3), EVP_PKEY_decrypt_init_ex(3) and EVP_PKEY_decrypt(3). Int RSA_private_decrypt(int flen, const unsigned char *from,īoth of the functions described on this page are deprecated.

Unsigned char *to, RSA *rsa, int padding) Int RSA_public_encrypt(int flen, const unsigned char *from, The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7): RSA_public_encrypt, RSA_private_decrypt - RSA public key cryptography

Python 3 openssl decrypt rsa