2 Copyright (C) 2018 Carl Hetherington <cth@carlh.net>
4 This file is part of DCP-o-matic.
6 DCP-o-matic is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 DCP-o-matic is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with DCP-o-matic. If not, see <http://www.gnu.org/licenses/>.
21 /* Based on code from https://wiki.openssl.org/index.php/EVP_Symmetric_Encryption_and_Decryption */
24 #include "exceptions.h"
25 #include <openssl/conf.h>
26 #include <openssl/evp.h>
27 #include <openssl/err.h>
28 #include <openssl/rand.h>
29 #include <boost/scoped_array.hpp>
32 using namespace dcpomatic;
34 /** The cipher that this code uses */
35 #define CIPHER EVP_aes_256_cbc()
38 dcpomatic::random_iv ()
40 EVP_CIPHER const * cipher = CIPHER;
41 dcp::Data iv (EVP_CIPHER_iv_length(cipher));
42 RAND_bytes (iv.data().get(), iv.size());
47 dcpomatic::encrypt (string plaintext, dcp::Data key, dcp::Data iv)
49 EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new ();
51 throw CryptoError ("could not create cipher context");
54 int r = EVP_EncryptInit_ex (ctx, CIPHER, 0, key.data().get(), iv.data().get());
56 throw CryptoError ("could not initialise cipher context for encryption");
59 dcp::Data ciphertext (plaintext.size() * 2);
62 r = EVP_EncryptUpdate (ctx, ciphertext.data().get(), &len, (uint8_t const *) plaintext.c_str(), plaintext.size());
64 throw CryptoError ("could not encrypt data");
67 int ciphertext_len = len;
69 r = EVP_EncryptFinal_ex (ctx, ciphertext.data().get() + len, &len);
71 throw CryptoError ("could not finish encryption");
74 ciphertext.set_size (ciphertext_len + len);
76 EVP_CIPHER_CTX_free (ctx);
82 dcpomatic::decrypt (dcp::Data ciphertext, dcp::Data key, dcp::Data iv)
84 EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new ();
86 throw CryptoError ("could not create cipher context");
89 int r = EVP_DecryptInit_ex (ctx, CIPHER, 0, key.data().get(), iv.data().get());
91 throw CryptoError ("could not initialise cipher context for decryption");
94 dcp::Data plaintext (ciphertext.size() * 2);
97 r = EVP_DecryptUpdate (ctx, plaintext.data().get(), &len, ciphertext.data().get(), ciphertext.size());
99 throw CryptoError ("could not decrypt data");
102 int plaintext_len = len;
104 r = EVP_DecryptFinal_ex (ctx, plaintext.data().get() + len, &len);
106 throw CryptoError ("could not finish decryption");
109 plaintext_len += len;
110 plaintext.set_size (plaintext_len + 1);
111 plaintext.data().get()[plaintext_len] = '\0';
113 EVP_CIPHER_CTX_free (ctx);
115 return string ((char *) plaintext.data().get());
119 dcpomatic::crypto_key_length ()
121 return EVP_CIPHER_key_length (CIPHER);