83 lines
3.1 KiB
C
83 lines
3.1 KiB
C
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#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 <cryptopp/cryptopp/gcm.h>
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#include "Cipher.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 = FixedSizeData<KeySize>;
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static EncryptionKey CreateKey(RandomGenerator &randomGenerator) {
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return randomGenerator.getFixedSize<EncryptionKey::BINARY_LENGTH>();
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}
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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 byte *plaintext, unsigned int plaintextSize, const EncryptionKey &encKey);
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static boost::optional<Data> decrypt(const 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<typename BlockCipher, unsigned int KeySize>
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Data GCM_Cipher<BlockCipher, KeySize>::encrypt(const byte *plaintext, unsigned int plaintextSize, const EncryptionKey &encKey) {
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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(encKey.data(), encKey.BINARY_LENGTH, iv.data(), IV_SIZE);
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Data ciphertext(ciphertextSize(plaintextSize));
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std::memcpy(ciphertext.data(), iv.data(), IV_SIZE);
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CryptoPP::ArraySource(plaintext, plaintextSize, true,
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new CryptoPP::AuthenticatedEncryptionFilter(encryption,
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new CryptoPP::ArraySink((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 byte *ciphertext, unsigned int ciphertextSize, const EncryptionKey &encKey) {
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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 byte *ciphertextIV = ciphertext;
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const 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((byte*)encKey.data(), encKey.BINARY_LENGTH, ciphertextIV, IV_SIZE);
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Data plaintext(plaintextSize(ciphertextSize));
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try {
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CryptoPP::ArraySource((byte*)ciphertextData, ciphertextSize - IV_SIZE, true,
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new CryptoPP::AuthenticatedDecryptionFilter(decryption,
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new CryptoPP::ArraySink((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 std::move(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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