1=pod 2 3=head1 NAME 4 5EVP_OpenInit, EVP_OpenUpdate, EVP_OpenFinal - EVP envelope decryption 6 7=head1 SYNOPSIS 8 9 #include <openssl/evp.h> 10 11 int EVP_OpenInit(EVP_CIPHER_CTX *ctx, EVP_CIPHER *type, unsigned char *ek, 12 int ekl, unsigned char *iv, EVP_PKEY *priv); 13 int EVP_OpenUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, 14 int *outl, unsigned char *in, int inl); 15 int EVP_OpenFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl); 16 17=head1 DESCRIPTION 18 19The EVP envelope routines are a high-level interface to envelope 20decryption. They decrypt a public key encrypted symmetric key and 21then decrypt data using it. 22 23EVP_OpenInit() initializes a cipher context B<ctx> for decryption 24with cipher B<type>. It decrypts the encrypted symmetric key of length 25B<ekl> bytes passed in the B<ek> parameter using the private key B<priv>. 26The IV is supplied in the B<iv> parameter. 27 28EVP_OpenUpdate() and EVP_OpenFinal() have exactly the same properties 29as the EVP_DecryptUpdate() and EVP_DecryptFinal() routines, as 30documented on the L<EVP_EncryptInit(3)> manual 31page. 32 33=head1 NOTES 34 35It is possible to call EVP_OpenInit() twice in the same way as 36EVP_DecryptInit(). The first call should have B<priv> set to NULL 37and (after setting any cipher parameters) it should be called again 38with B<type> set to NULL. 39 40If the cipher passed in the B<type> parameter is a variable length 41cipher then the key length will be set to the value of the recovered 42key length. If the cipher is a fixed length cipher then the recovered 43key length must match the fixed cipher length. 44 45=head1 RETURN VALUES 46 47EVP_OpenInit() returns 0 on error or a non zero integer (actually the 48recovered secret key size) if successful. 49 50EVP_OpenUpdate() returns 1 for success or 0 for failure. 51 52EVP_OpenFinal() returns 0 if the decrypt failed or 1 for success. 53 54=head1 SEE ALSO 55 56L<evp(7)>, L<RAND_bytes(3)>, 57L<EVP_EncryptInit(3)>, 58L<EVP_SealInit(3)> 59 60=head1 COPYRIGHT 61 62Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. 63 64Licensed under the Apache License 2.0 (the "License"). You may not use 65this file except in compliance with the License. You can obtain a copy 66in the file LICENSE in the source distribution or at 67L<https://www.openssl.org/source/license.html>. 68 69=cut 70