NAME
EVP_OpenInit, EVP_OpenUpdate, EVP_OpenFinal — EVP envelope decryption
Synopsis
#include <openssl/evp.h>
int
EVP_OpenInit(EVP_CIPHER_CTX *ctx,EVP_CIPHER *type,unsigned char
*ek, int ekl,unsigned char *iv,EVP_PKEY *priv);
int EVP_OpenUpdate(EVP_CIPHER_CTX
*ctx, unsigned char *out, int *outl, unsigned char *in, int inl);
int
EVP_OpenFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
DESCRIPTION
The EVP envelope routines are a high level interface to envelope
decryption. They decrypt a public key encrypted symmetric key and
then decrypt data using it.
EVP_OpenInit() initializes a cipher context ctx for
decryption with cipher type. It decrypts the
encrypted symmetric key of length ekl bytes
passed in the ek parameter using the private
key priv. The IV is supplied in the iv parameter.
EVP_OpenUpdate() and EVP_OpenFinal() have exactly the same
properties as the EVP_DecryptUpdate() and EVP_DecryptFinal() routines,
as documented on the EVP_EncryptInit(3) manual page.
NOTES
It is possible to call EVP_OpenInit() twice in the same way
as EVP_DecryptInit(). The first call should have priv set
to NULL and (after setting any cipher parameters) it should be called
again with type set to NULL.
If the cipher passed in the type parameter
is a variable length cipher then the key length will be set to the value
of the recovered key length. If the cipher is a fixed length cipher
then the recovered key length must match the fixed cipher length.
RETURN VALUES
EVP_OpenInit() returns 0 on error or a non zero integer (actually
the recovered secret key size) if successful.
EVP_OpenUpdate() returns 1 for success or 0 for failure.
EVP_OpenFinal() returns 0 if the decrypt failed or 1 for success.
SEE ALSO
evp(3), rand(3), EVP_EncryptInit(3), EVP_SealInit(3)
