Set encryption padding in Poco Crypto - poco-libraries

Question

Is there a possibility to set the padding for encryption with AES128 in Poco Crypto? I can't find any option for this.
std::string Crypto::Encrypt(const std::string &input, const std::string &key)
{
Poco::Crypto::Cipher::ByteVec iv { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
Poco::Crypto::Cipher::ByteVec key2 {key.begin(), key.end()};
Poco::Crypto::Cipher::Ptr pCipher = Poco::Crypto::CipherFactory::defaultFactory()
.createCipher(Poco::Crypto::CipherKey("aes128", key2, iv));
std::string output = pCipher->encryptString(input);
return std::move(output);
}
In simple OpenSSL I have this option:
EVP_CIPHER_CTX *ctx;
EVP_CIPHER_CTX_set_padding(ctx, 0)

Answer 1

By default padding is enabled.
From comment in Crypto/include/Poco/Crypto/CryptoTransform.h or https://pocoproject.org/docs/Poco.Crypto.CryptoTransform.html#230, encryption operations are padded by default.
...
virtual int setPadding(int padding);
/// Enables or disables padding. By default encryption operations are padded using standard block
/// padding and the padding is checked and removed when decrypting. If the padding parameter is zero then
/// no padding is performed, the total amount of data encrypted or decrypted must then be a multiple of
/// the block size or an error will occur.
...
If you want to change padding option, you should override createEncryptor(), creatoreDecryptor() in Poco::Crypto::Cipher like below
class CipherWithPadding : public Poco::Crypto::Cipher
{
public:
// by default no padding, for more information refer to CryptoTransform::setPadding
CipherWithPadding(Poco::Crypto::Cipher::Ptr cipher_impl, int padding = 0)
: cipher_(cipher_impl)
, padding_(padding)
{
}
virtual ~CipherWithPadding()
{
}
virtual const std::string& name() const
{
return cipher_->name();
}
virtual Poco::Crypto::CryptoTransform* createEncryptor() override
{
auto ptransform = cipher_->createEncryptor();
if (ptransform)
ptransform->setPadding(padding_);
return ptransform;
}
virtual Poco::Crypto::CryptoTransform* createDecryptor() override
{
auto ptransform = cipher_->createDecryptor();
if (ptransform)
ptransform->setPadding(padding_);
return ptransform;
}
protected:
int padding_;
Poco::Crypto::Cipher::Ptr cipher_;
protected:
CipherWithPadding();
private:
CipherWithPadding(const CipherWithPadding&);
CipherWithPadding& operator= (const CipherWithPadding&);
};
Then your function should be like below
std::string Crypto::Encrypt(const std::string &input, const std::string &key)
{
Poco::Crypto::Cipher::ByteVec iv { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
Poco::Crypto::Cipher::ByteVec key2 {key.begin(), key.end()};
CipherWithPadding cipher(Poco::Crypto::CipherFactory::defaultFactory()
.createCipher(Poco::Crypto::CipherKey("aes128", key2, iv)));
std::string output = cipher.encryptString(input);
return std::move(output);
}