ciphertest.cpp

The code below shows the normal way to use the QCA::Cipher class.

00001 /*
00002  Copyright (C) 2003 Justin Karneges <justin@affinix.com>
00003  Copyright (C) 2005-2006 Brad Hards <bradh@frogmouth.net>
00004 
00005  Permission is hereby granted, free of charge, to any person obtaining a copy
00006  of this software and associated documentation files (the "Software"), to deal
00007  in the Software without restriction, including without limitation the rights
00008  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00009  copies of the Software, and to permit persons to whom the Software is
00010  furnished to do so, subject to the following conditions:
00011 
00012  The above copyright notice and this permission notice shall be included in
00013  all copies or substantial portions of the Software.
00014 
00015  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00016  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00017  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
00018  AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
00019  AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
00020  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00021 */
00022 
00023 // QtCrypto has the declarations for all of QCA
00024 #include <QtCrypto>
00025 #include <stdio.h>
00026 
00027 #include <QCoreApplication>
00028 
00029 int main(int argc, char **argv)
00030 {
00031     QCoreApplication app(argc, argv);
00032 
00033     // the Initializer object sets things up, and
00034     // also does cleanup when it goes out of scope
00035     QCA::Initializer init;
00036 
00037     // we use the first argument if provided, or
00038     // use "hello" if no arguments
00039     QCA::SecureArray arg = (argc >= 2) ? argv[1] : "hello";
00040 
00041     // AES128 testing
00042     if(!QCA::isSupported("aes128-cbc-pkcs7"))
00043         printf("AES128-CBC not supported!\n");
00044     else {
00045         // Create a random key - you'd probably use one from another
00046         // source in a real application
00047         QCA::SymmetricKey key(16);
00048 
00049         // Create a random initialisation vector - you need this
00050         // value to decrypt the resulting cipher text, but it
00051         // need not be kept secret (unlike the key).
00052         QCA::InitializationVector iv(16);
00053 
00054         // create a 128 bit AES cipher object using Cipher Block Chaining (CBC) mode
00055         QCA::Cipher cipher(QString("aes128"),QCA::Cipher::CBC,
00056                            // use Default padding, which is equivalent to PKCS7 for CBC
00057                            QCA::Cipher::DefaultPadding,
00058                            // this object will encrypt
00059                            QCA::Encode,
00060                            key, iv);
00061 
00062         // we use the cipher object to encrypt the argument we passed in
00063         // the result of that is returned - note that if there is less than
00064         // 16 bytes (1 block), then nothing will be returned - it is buffered
00065         // update() can be called as many times as required.
00066         QCA::SecureArray u = cipher.update(arg);
00067 
00068         // We need to check if that update() call worked.
00069         if (!cipher.ok()) {
00070             printf("Update failed\n");
00071         }
00072         // output the results of that stage
00073         printf("AES128 encryption of %s is [%s]\n",
00074                arg.data(),
00075                qPrintable(QCA::arrayToHex(u.toByteArray())) );
00076 
00077 
00078         // Because we are using PKCS7 padding, we need to output the final (padded) block
00079         // Note that we should always call final() even with no padding, to clean up
00080         QCA::SecureArray f = cipher.final();
00081 
00082         // Check if the final() call worked
00083         if (!cipher.ok()) {
00084             printf("Final failed\n");
00085         }
00086         // and output the resulting block. The ciphertext is the results of update()
00087         // and the result of final()
00088         printf("Final block for AES128 encryption is [0x%s]\n", qPrintable(QCA::arrayToHex(f.toByteArray())) );
00089 
00090         // re-use the Cipher t decrypt. We need to use the same key and
00091         // initialisation vector as in the encryption.
00092         cipher.setup( QCA::Decode, key, iv );
00093 
00094         // Build a single cipher text array. You could also call update() with
00095         // each block as you receive it, if that is more useful.
00096         QCA::SecureArray cipherText = u.append(f);
00097 
00098         // take that cipher text, and decrypt it
00099         QCA::SecureArray plainText = cipher.update(cipherText);
00100 
00101         // check if the update() call worked
00102         if (!cipher.ok()) {
00103             printf("Update failed\n");
00104         }
00105 
00106         // output results
00107         printf("Decryption using AES128 of [0x%s] is %s\n",
00108                qPrintable(QCA::arrayToHex(cipherText.toByteArray())), plainText.data());
00109 
00110         // Again we need to call final(), to get the last block (with its padding removed)
00111         plainText = cipher.final();
00112 
00113         // check if the final() call worked
00114         if (!cipher.ok()) {
00115             printf("Final failed\n");
00116         }
00117 
00118         // output results
00119         printf("Final decryption block using AES128 is %s\n", plainText.data());
00120         // instead of update() and final(), you can do the whole thing
00121         // in one step, using process()
00122         printf("One step decryption using AES128: %s\n",
00123                QCA::SecureArray(cipher.process(cipherText)).data() );
00124 
00125     }
00126 
00127     return 0;
00128 }
00129 

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