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Fix FakeAuthenticatedCipher test flakyness

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This commit is contained in:
Sebastian Messmer 2017-12-01 23:55:41 +00:00
parent cc7b38b3c1
commit d90e27eb11
1 changed files with 38 additions and 31 deletions
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69
src/cpp-utils/crypto/symmetric/testutils/FakeAuthenticatedCipher.h
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@ -13,20 +13,20 @@ namespace cpputils {
struct FakeKey {
static FakeKey FromBinary(const void *data) {
return FakeKey{*(uint8_t *) data};
return FakeKey{*(uint64_t *) data};
}
static constexpr unsigned int BINARY_LENGTH = 1;
static constexpr unsigned int BINARY_LENGTH = sizeof(uint64_t);
static FakeKey CreateKey(RandomGenerator &randomGenerator) {
auto data = randomGenerator.getFixedSize<1>();
return FakeKey{*((uint8_t *) data.data())};
auto data = randomGenerator.getFixedSize<sizeof(uint64_t)>();
return FakeKey{*((uint64_t *) data.data())};
}
uint8_t value;
uint64_t value;
};
// This is a fake cipher that uses an indeterministic caesar chiffre and a 4-byte checksum for a simple authentication mechanism
// This is a fake cipher that uses an indeterministic xor chiffre and a 8-byte checksum for a simple authentication mechanism
class FakeAuthenticatedCipher {
public:
BOOST_CONCEPT_ASSERT((CipherConcept<FakeAuthenticatedCipher>));
@ -42,71 +42,78 @@ namespace cpputils {
}
static constexpr unsigned int ciphertextSize(unsigned int plaintextBlockSize) {
return plaintextBlockSize + 5;
return plaintextBlockSize + sizeof(uint64_t) + sizeof(uint64_t);
}
static constexpr unsigned int plaintextSize(unsigned int ciphertextBlockSize) {
return ciphertextBlockSize - 5;
return ciphertextBlockSize - sizeof(uint64_t) - sizeof(uint64_t);
}
static Data encrypt(const CryptoPP::byte *plaintext, unsigned int plaintextSize, const EncryptionKey &encKey) {
Data result(ciphertextSize(plaintextSize));
//Add a random IV
uint8_t iv = std::uniform_int_distribution<uint8_t>()(random_);
std::memcpy(result.data(), &iv, 1);
uint64_t iv = std::uniform_int_distribution<uint64_t>()(random_);
std::memcpy(result.data(), &iv, sizeof(uint64_t));
//Use caesar chiffre on plaintext
_caesar((CryptoPP::byte *) result.data() + 1, plaintext, plaintextSize, encKey.value + iv);
//Use xor chiffre on plaintext
_xor((CryptoPP::byte *) result.data() + sizeof(uint64_t), plaintext, plaintextSize, encKey.value ^ iv);
//Add checksum information
int32_t checksum = _checksum((CryptoPP::byte *) result.data(), encKey, plaintextSize + 1);
std::memcpy((CryptoPP::byte *) result.data() + plaintextSize + 1, &checksum, 4);
uint64_t checksum = _checksum((CryptoPP::byte *) result.data(), encKey, plaintextSize + sizeof(uint64_t));
std::memcpy((CryptoPP::byte *) result.data() + plaintextSize + sizeof(uint64_t), &checksum, sizeof(uint64_t));
return result;
}
static boost::optional <Data> decrypt(const CryptoPP::byte *ciphertext, unsigned int ciphertextSize,
const EncryptionKey &encKey) {
//We need at least 5 bytes (iv + checksum)
if (ciphertextSize < 5) {
//We need at least 16 bytes (iv + checksum)
if (ciphertextSize < 16) {
return boost::none;
}
//Check checksum
int32_t expectedParity = _checksum(ciphertext, encKey, plaintextSize(ciphertextSize) + 1);
int32_t actualParity = *(int32_t * )(ciphertext + plaintextSize(ciphertextSize) + 1);
uint64_t expectedParity = _checksum(ciphertext, encKey, plaintextSize(ciphertextSize) + sizeof(uint64_t));
uint64_t actualParity = *(uint64_t * )(ciphertext + plaintextSize(ciphertextSize) + sizeof(uint64_t));
if (expectedParity != actualParity) {
return boost::none;
}
//Decrypt caesar chiffre from ciphertext
int32_t iv = *(int32_t *) ciphertext;
//Decrypt xor chiffre from ciphertext
uint64_t iv = *(uint64_t *) ciphertext;
Data result(plaintextSize(ciphertextSize));
_caesar((CryptoPP::byte *) result.data(), ciphertext + 1, plaintextSize(ciphertextSize), -(encKey.value + iv));
_xor((CryptoPP::byte *) result.data(), ciphertext + sizeof(uint64_t), plaintextSize(ciphertextSize), encKey.value ^ iv);
return std::move(result);
}
static constexpr const char *NAME = "FakeAuthenticatedCipher";
private:
static int32_t _checksum(const CryptoPP::byte *data, FakeKey encKey, unsigned int size) {
int32_t checksum = 34343435 * encKey.value; // some init value
const int32_t *intData = reinterpret_cast<const int32_t *>(data);
unsigned int intSize = size / sizeof(int32_t);
static uint64_t _checksum(const CryptoPP::byte *data, FakeKey encKey, unsigned int size) {
uint64_t checksum = 34343435 * encKey.value; // some init value
const uint64_t *intData = reinterpret_cast<const uint64_t *>(data);
unsigned int intSize = size / sizeof(uint64_t);
for (unsigned int i = 0; i < intSize; ++i) {
checksum = ((int64_t)checksum) + intData[i];
checksum = ((uint64_t)checksum) + intData[i];
}
unsigned int remainingBytes = size - 4 * intSize;
unsigned int remainingBytes = size - sizeof(uint64_t) * intSize;
for (unsigned int i = 0; i < remainingBytes; ++i) {
checksum = ((int64_t)checksum) + (data[4 * intSize + i] << (24 - 8 * i));
checksum = ((uint64_t)checksum) + (data[8 * intSize + i] << (56 - 8 * i));
}
return checksum;
}
static void _caesar(CryptoPP::byte *dst, const CryptoPP::byte *src, unsigned int size, uint8_t key) {
for (unsigned int i = 0; i < size; ++i) {
dst[i] = src[i] + key;
static void _xor(CryptoPP::byte *dst, const CryptoPP::byte *src, unsigned int size, uint64_t key) {
const uint64_t *srcIntData = reinterpret_cast<const uint64_t *>(src);
uint64_t *dstIntData = reinterpret_cast<uint64_t *>(dst);
unsigned int intSize = size / sizeof(uint64_t);
for (unsigned int i = 0; i < intSize; ++i) {
dstIntData[i] = srcIntData[i] ^ key;
}
unsigned int remainingBytes = size - sizeof(uint64_t) * intSize;
for (unsigned int i = 0; i < remainingBytes; ++i) {
dst[8 * intSize + i] = src[8 * intSize + i] ^ ((key >> (56 - 8*i)) & 0xFF);
}
}