hardcoresushi/libcryfs
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CryFS asks back if a cipher without integrity is chosen

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This commit is contained in:
Sebastian Messmer 2015-09-04 16:02:55 +02:00
parent a9a5a5d04d
commit a665e6cdd7
4 changed files with 44 additions and 18 deletions
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35
src/CryCipher.cpp
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@ -10,6 +10,8 @@ using cpputils::make_unique_ref;
using blockstore::BlockStore;
using std::shared_ptr;
using std::make_shared;
using boost::optional;
using boost::none;
using namespace cryfs;
using namespace blockstore::encrypted;
@ -19,13 +21,17 @@ class CryCipherInstance: public CryCipher {
public:
BOOST_CONCEPT_ASSERT((CipherConcept<Cipher>));
CryCipherInstance(const std::string &cipherName): _cipherName(cipherName) {
CryCipherInstance(const std::string &cipherName, const optional<string> warning = none): _cipherName(cipherName), _warning(warning) {
}
string cipherName() const override {
const string &cipherName() const override {
return _cipherName;
}
const optional<string> &warning() const override {
return _warning;
}
unique_ref<BlockStore> createEncryptedBlockstore(unique_ref<BlockStore> baseBlockStore, const string &encKey) const override {
return make_unique_ref<EncryptedBlockStore<Cipher>>(std::move(baseBlockStore), Cipher::EncryptionKey::FromString(encKey));
}
@ -36,30 +42,33 @@ public:
private:
string _cipherName;
optional<string> _warning;
};
const string INTEGRITY_WARNING = "This cipher does not ensure integrity.";
//We have to use shared_ptr instead of unique_ref, because c++ initializer_list needs copyable values
const vector<shared_ptr<CryCipher>> CryCiphers::SUPPORTED_CIPHERS = {
make_shared<CryCipherInstance<AES256_GCM>>("aes-256-gcm"),
make_shared<CryCipherInstance<AES256_CFB>>("aes-256-cfb"),
make_shared<CryCipherInstance<AES256_CFB>>("aes-256-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<AES128_GCM>>("aes-128-gcm"),
make_shared<CryCipherInstance<AES128_CFB>>("aes-128-cfb"),
make_shared<CryCipherInstance<AES128_CFB>>("aes-128-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Twofish256_GCM>>("twofish-256-gcm"),
make_shared<CryCipherInstance<Twofish256_CFB>>("twofish-256-cfb"),
make_shared<CryCipherInstance<Twofish256_CFB>>("twofish-256-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Twofish128_GCM>>("twofish-128-gcm"),
make_shared<CryCipherInstance<Twofish128_CFB>>("twofish-128-cfb"),
make_shared<CryCipherInstance<Twofish128_CFB>>("twofish-128-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Serpent256_GCM>>("serpent-256-gcm"),
make_shared<CryCipherInstance<Serpent256_CFB>>("serpent-256-cfb"),
make_shared<CryCipherInstance<Serpent256_CFB>>("serpent-256-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Serpent128_GCM>>("serpent-128-gcm"),
make_shared<CryCipherInstance<Serpent128_CFB>>("serpent-128-cfb"),
make_shared<CryCipherInstance<Serpent128_CFB>>("serpent-128-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Cast256_GCM>>("cast-256-gcm"),
make_shared<CryCipherInstance<Cast256_CFB>>("cast-256-cfb"),
make_shared<CryCipherInstance<Cast256_CFB>>("cast-256-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Mars448_GCM>>("mars-448-gcm"),
make_shared<CryCipherInstance<Mars448_CFB>>("mars-448-cfb"),
make_shared<CryCipherInstance<Mars448_CFB>>("mars-448-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Mars256_GCM>>("mars-256-gcm"),
make_shared<CryCipherInstance<Mars256_CFB>>("mars-256-cfb"),
make_shared<CryCipherInstance<Mars256_CFB>>("mars-256-cfb", INTEGRITY_WARNING),
make_shared<CryCipherInstance<Mars128_GCM>>("mars-128-gcm"),
make_shared<CryCipherInstance<Mars128_CFB>>("mars-128-cfb")
make_shared<CryCipherInstance<Mars128_CFB>>("mars-128-cfb", INTEGRITY_WARNING)
};
const CryCipher& CryCiphers::find(const string &cipherName) {
@ -71,7 +80,7 @@ const CryCipher& CryCiphers::find(const string &cipherName) {
return **found;
}
vector<string> CryCiphers::supportedCiphers() {
vector<string> CryCiphers::supportedCipherNames() {
vector<string> result;
for (const auto& cipher : CryCiphers::SUPPORTED_CIPHERS) {
result.push_back(cipher->cipherName());

5
src/CryCipher.h
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@ -10,14 +10,15 @@ namespace cryfs {
class CryCipher {
public:
virtual std::string cipherName() const = 0;
virtual const std::string &cipherName() const = 0;
virtual const boost::optional<std::string> &warning() const = 0;
virtual cpputils::unique_ref<blockstore::BlockStore> createEncryptedBlockstore(cpputils::unique_ref<blockstore::BlockStore> baseBlockStore, const std::string &encKey) const = 0;
virtual std::string createKey() const = 0;
};
class CryCiphers {
public:
static std::vector<std::string> supportedCiphers();
static std::vector<std::string> supportedCipherNames();
static const CryCipher& find(const std::string &cipherName);

20
src/CryConfigLoader.cpp
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@ -43,9 +43,23 @@ void CryConfigLoader::_initializeConfigWithWeakKey(CryConfig *config) {
}
void CryConfigLoader::_generateCipher(CryConfig *config) {
vector<string> ciphers = CryCiphers::supportedCiphers();
int cipherIndex = _console->ask("Which block cipher do you want to use?", ciphers);
config->SetCipher(ciphers[cipherIndex]);
vector<string> ciphers = CryCiphers::supportedCipherNames();
string cipherName = "";
bool askAgain = true;
while(askAgain) {
int cipherIndex = _console->ask("Which block cipher do you want to use?", ciphers);
cipherName = ciphers[cipherIndex];
askAgain = !_showWarningForCipherAndReturnIfOk(cipherName);
};
config->SetCipher(cipherName);
}
bool CryConfigLoader::_showWarningForCipherAndReturnIfOk(const string &cipherName) {
auto warning = CryCiphers::find(cipherName).warning();
if (warning == boost::none) {
return true;
}
return _console->askYesNo(string() + (*warning) + " Do you want to take this cipher nevertheless?");
}
void CryConfigLoader::_generateEncKey(CryConfig *config) {

2
src/CryConfigLoader.h
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@ -35,6 +35,8 @@ private:
void _generateWeakEncKey(CryConfig *config); // TODO Rename to _generateTestEncKey
void _generateTestCipher(CryConfig *config);
bool _showWarningForCipherAndReturnIfOk(const std::string &cipherName);
cpputils::unique_ref<Console> _console;
};