[Qt-interest] QCA big string encryption

[Jason H]

http://delta.affinix.com/docs/qca/ciphertest_8cpp-example.html#_a7 shows 
everything you need to know.
process() is the convince function which combines update() with finalize()






----- Original Message ----
From: Nicholas Shatokhin <n.shatokhin at gmail.com>
To: qt-interest at qt.nokia.com; Jason H <scorp1us at yahoo.com>
Sent: Sun, April 24, 2011 3:11:56 PM
Subject: Re: [Qt-interest] QCA big string encryption

What class contain method finalize?
How can I realize encode/decode by RSA with QCA?

Sun, 24 Apr 2011 22:06:22 +0300 було написано Jason H <scorp1us at yahoo.com>:

> Generally you need an IV (Initialization vector) this then is fed to the
> routines with the keys. The IV is an important random number so that if you 
can
> encrypt the same message with the same keys multiple times and not get the 
same
> encrypted message (thus ruling out a dictionary attack)
> 
> Anyway, there are two types of cyphers, block and stream. With block cyphers,
> you work a block at a time. The last block will usually be incomplete, and 
>there
> is some final[ize[() method for handling this special block. Normally, the
> enc/decrypt functions in QCA will give you all complete blocks, leaving you to
> call finalize().
> 
> QCA does have convince functions that will do it all without you having to 
call
> finalize(), HOWEVER this should only be used for messages of known, short
> lengths. The non-convenience functions are designed to be used in a streaming
> manner, which is better for memory and scalability.
> 
> 
> 
> HTH, but AFAIAC, this is a QCA question, not a Qt question.
> 
> 
> 
> 
> ----- Original Message ----
> From: Nicholas Shatokhin <n.shatokhin at gmail.com>
> To: qt-interest at qt.nokia.com; Jason H <scorp1us at yahoo.com>
> Sent: Sun, April 24, 2011 2:52:53 PM
> Subject: Re: [Qt-interest] QCA big string encryption
> 
> What do you mean?
> 
> There is my code below. What must I add? (I use 1024bit rsa key and message
> truncate to 1024bit)
> 
> 
> bool CCryptor::generateKeys(int size)
> {
>     if(init())
>     {
>         QCA::PrivateKey seckey = QCA::KeyGenerator().createRSA(size);
> 
>         if(seckey.isNull())
>         {
>             std::cout << "Failed to make private RSA key" << std::endl;
>             return false;
>         }
> 
>         QCA::PublicKey pubkey = seckey.toPublicKey();
> 
>         privateKey = seckey;
>         publicKey = pubkey;
> 
>         return true;
>     }
>     else
>         return false;
> }
> 
> QByteArray CCryptor::dataEnrypt(QByteArray data)
> {
>     // check if the key can encrypt
>     if(!publicKey.canEncrypt())
>     {
>         std::cout << "Error: this kind of key cannot encrypt" << std::endl;
>         return QByteArray();
>     }
> 
>     QCA::SecureArray arg = data;
> 
>     // encrypt some data - note that only the public key is required
>     // you must also choose the algorithm to be used
>     QCA::SecureArray result = publicKey.encrypt(arg, QCA::EME_PKCS1_OAEP);
> 
>     if(result.isEmpty()) {
>         std::cout << "Error encrypting" << std::endl;
>         return QByteArray();
>     }
> 
>     return result.toByteArray();
> }
> 
> QByteArray CCryptor::dataDecrypt(QByteArray data)
> {
>     QCA::SecureArray encrypt = data;
>     QCA::SecureArray decrypt;
>     if(0 == privateKey.decrypt(encrypt, &decrypt, QCA::EME_PKCS1_OAEP))
>     {
>         std::cout << "Error decrypting.\n";
>         return QByteArray();
>     }
> 
>     return decrypt.data();
> }
> 
> 
> 
> Sun, 24 Apr 2011 21:31:38 +0300 було написано Jason H <scorp1us at yahoo.com>:
> 
>> It's beena  while since I used QCA, but do you need to finalize() it for the
>> last block?
>> 
>> 
>> 
>> 
>> ----- Original Message ----
>> From: Nicholas Shatokhin <n.shatokhin at gmail.com>
>> To: qt-interest at qt.nokia.com
>> Sent: Sun, April 24, 2011 1:12:41 PM
>> Subject: [Qt-interest] QCA big string encryption
>> 
>> Hello.
>> 
>> I'm trying to encrypt end decrypt long string. But after decryption, I get
>> only part of string. What's wrong?
>> 
>> Code:
>> 
>>      QCA::SecureArray arg = data;
>>      qDebug() << arg.toByteArray();
>>      QCA::SecureArray result = publicKey.encrypt(arg, QCA::EME_PKCS1_OAEP);
>>      privateKey.decrypt(result, &arg, QCA::EME_PKCS1_OAEP);
>>      qDebug() << arg.toByteArray();
>> 
>> Output:
>> 
>> "{"method": 1, "data": {"email": "dfgh", "usePassword": "false",
>> "password": "", "useFingerprint": false, "fingerprint": "", "publicKey":
>>"LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUlHZk1BMEdDU3FHU0liM0RRRUJBUVVBQTRHTkFEQ0JpUUtCZ1FDN05UNjd6R1pHajZpbDc5K3ErOWo5K2s5cApnVHJJOGxRVlFoQkxuVWxBNFArS01selBEOU9aOEk0UXRWNEdjT0ZOYWFyTjByZFlacllKaVF2VjBUQkdSSnRWCnNEOTVsZzNPMHFzVHBuSVdrYW5rUTVFUmdiTDlqQ0grb0taNFBrUEd0OW9MVjhCOGphNjFRazdhLytBVUZ1UUQKeDBMUGZvUyt5VkVoYXNjM0x3SURBUUFCCi0tLS0tRU5EIFBVQkxJQyBLRVktLS0tLQo="}
>>}
>> }
>> }"
>> 
>> "{"method": 1, "data": {"email": "dfgh", "usePassword": "false",
>> "password": "", "useFi"
>> 
>> 
>> Best regards,
>> Nick.
>> 
> 
> 
> --За використання революційного клієнта електронної пошти Opera:
> http://www.opera.com/mail/
> 


--За використання революційного клієнта електронної пошти Opera: 
http://www.opera.com/mail/