92 lines
3.6 KiB
C++
92 lines
3.6 KiB
C++
#pragma once
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#ifndef MESSMER_CPPUTILS_CRYPTO_SYMMETRIC_GCMCIPHER_H_
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#define MESSMER_CPPUTILS_CRYPTO_SYMMETRIC_GCMCIPHER_H_
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#include "../../data/FixedSizeData.h"
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#include "../../data/Data.h"
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#include "../../random/Random.h"
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#include <vendor_cryptopp/gcm.h>
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#include "Cipher.h"
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#include "EncryptionKey.h"
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namespace cpputils {
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template<typename BlockCipher, unsigned int KeySize>
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class GCM_Cipher {
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public:
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using EncryptionKey = cpputils::EncryptionKey;
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static constexpr unsigned int KEYSIZE = KeySize;
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static constexpr unsigned int STRING_KEYSIZE = 2 * KEYSIZE;
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static constexpr unsigned int ciphertextSize(unsigned int plaintextBlockSize) {
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return plaintextBlockSize + IV_SIZE + TAG_SIZE;
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}
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static constexpr unsigned int plaintextSize(unsigned int ciphertextBlockSize) {
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return ciphertextBlockSize - IV_SIZE - TAG_SIZE;
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}
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static Data encrypt(const CryptoPP::byte *plaintext, unsigned int plaintextSize, const EncryptionKey &encKey);
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static boost::optional<Data> decrypt(const CryptoPP::byte *ciphertext, unsigned int ciphertextSize, const EncryptionKey &encKey);
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private:
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static constexpr unsigned int IV_SIZE = BlockCipher::BLOCKSIZE;
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static constexpr unsigned int TAG_SIZE = 16;
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};
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template<class BlockCipher, unsigned int KeySize>
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constexpr unsigned int GCM_Cipher<BlockCipher, KeySize>::KEYSIZE;
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template<class BlockCipher, unsigned int KeySize>
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constexpr unsigned int GCM_Cipher<BlockCipher, KeySize>::STRING_KEYSIZE;
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template<typename BlockCipher, unsigned int KeySize>
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Data GCM_Cipher<BlockCipher, KeySize>::encrypt(const CryptoPP::byte *plaintext, unsigned int plaintextSize, const EncryptionKey &encKey) {
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ASSERT(encKey.binaryLength() == KeySize, "Wrong key size");
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FixedSizeData<IV_SIZE> iv = Random::PseudoRandom().getFixedSize<IV_SIZE>();
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typename CryptoPP::GCM<BlockCipher, CryptoPP::GCM_64K_Tables>::Encryption encryption;
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encryption.SetKeyWithIV(static_cast<const CryptoPP::byte*>(encKey.data()), encKey.binaryLength(), iv.data(), IV_SIZE);
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Data ciphertext(ciphertextSize(plaintextSize));
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iv.ToBinary(ciphertext.data());
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CryptoPP::ArraySource(plaintext, plaintextSize, true,
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new CryptoPP::AuthenticatedEncryptionFilter(encryption,
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new CryptoPP::ArraySink(static_cast<CryptoPP::byte*>(ciphertext.data()) + IV_SIZE, ciphertext.size() - IV_SIZE),
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false, TAG_SIZE
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)
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);
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return ciphertext;
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}
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template<typename BlockCipher, unsigned int KeySize>
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boost::optional<Data> GCM_Cipher<BlockCipher, KeySize>::decrypt(const CryptoPP::byte *ciphertext, unsigned int ciphertextSize, const EncryptionKey &encKey) {
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ASSERT(encKey.binaryLength() == KeySize, "Wrong key size");
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if (ciphertextSize < IV_SIZE + TAG_SIZE) {
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return boost::none;
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}
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const CryptoPP::byte *ciphertextIV = ciphertext;
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const CryptoPP::byte *ciphertextData = ciphertext + IV_SIZE;
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typename CryptoPP::GCM<BlockCipher, CryptoPP::GCM_64K_Tables>::Decryption decryption;
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decryption.SetKeyWithIV(static_cast<const CryptoPP::byte*>(encKey.data()), encKey.binaryLength(), ciphertextIV, IV_SIZE);
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Data plaintext(plaintextSize(ciphertextSize));
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try {
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CryptoPP::ArraySource(static_cast<const CryptoPP::byte*>(ciphertextData), ciphertextSize - IV_SIZE, true,
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new CryptoPP::AuthenticatedDecryptionFilter(decryption,
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new CryptoPP::ArraySink(static_cast<CryptoPP::byte*>(plaintext.data()), plaintext.size()),
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CryptoPP::AuthenticatedDecryptionFilter::DEFAULT_FLAGS, TAG_SIZE
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)
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);
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return plaintext;
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} catch (const CryptoPP::HashVerificationFilter::HashVerificationFailed &e) {
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return boost::none;
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}
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}
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}
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#endif
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