[Qt-interest] QCA big string encryption

[Nicholas Shatokhin]

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.
>>
>
>
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