| yuezonghe | 824eb0c | 2024-06-27 02:32:26 -0700 | [diff] [blame] | 1 | =pod |
| 2 | |
| 3 | =head1 NAME |
| 4 | |
| 5 | EVP_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 | |
| 19 | The EVP envelope routines are a high-level interface to envelope |
| 20 | decryption. They decrypt a public key encrypted symmetric key and |
| 21 | then decrypt data using it. |
| 22 | |
| 23 | EVP_OpenInit() initializes a cipher context B<ctx> for decryption |
| 24 | with cipher B<type>. It decrypts the encrypted symmetric key of length |
| 25 | B<ekl> bytes passed in the B<ek> parameter using the private key B<priv>. |
| 26 | The IV is supplied in the B<iv> parameter. |
| 27 | |
| 28 | EVP_OpenUpdate() and EVP_OpenFinal() have exactly the same properties |
| 29 | as the EVP_DecryptUpdate() and EVP_DecryptFinal() routines, as |
| 30 | documented on the L<EVP_EncryptInit(3)> manual |
| 31 | page. |
| 32 | |
| 33 | =head1 NOTES |
| 34 | |
| 35 | It is possible to call EVP_OpenInit() twice in the same way as |
| 36 | EVP_DecryptInit(). The first call should have B<priv> set to NULL |
| 37 | and (after setting any cipher parameters) it should be called again |
| 38 | with B<type> set to NULL. |
| 39 | |
| 40 | If the cipher passed in the B<type> parameter is a variable length |
| 41 | cipher then the key length will be set to the value of the recovered |
| 42 | key length. If the cipher is a fixed length cipher then the recovered |
| 43 | key length must match the fixed cipher length. |
| 44 | |
| 45 | =head1 RETURN VALUES |
| 46 | |
| 47 | EVP_OpenInit() returns 0 on error or a non zero integer (actually the |
| 48 | recovered secret key size) if successful. |
| 49 | |
| 50 | EVP_OpenUpdate() returns 1 for success or 0 for failure. |
| 51 | |
| 52 | EVP_OpenFinal() returns 0 if the decrypt failed or 1 for success. |
| 53 | |
| 54 | =head1 SEE ALSO |
| 55 | |
| 56 | L<evp(7)>, L<RAND_bytes(3)>, |
| 57 | L<EVP_EncryptInit(3)>, |
| 58 | L<EVP_SealInit(3)> |
| 59 | |
| 60 | =head1 COPYRIGHT |
| 61 | |
| 62 | Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. |
| 63 | |
| 64 | Licensed under the OpenSSL license (the "License"). You may not use |
| 65 | this file except in compliance with the License. You can obtain a copy |
| 66 | in the file LICENSE in the source distribution or at |
| 67 | L<https://www.openssl.org/source/license.html>. |
| 68 | |
| 69 | =cut |