hardcoresushi/libcryfs
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Add a header to the inner config encryption so we can change the inner format later without changing the outer format

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This commit is contained in:
Sebastian Messmer 2015-10-27 21:20:12 +01:00
parent 0ae9bb7fca
commit bb507ce241
4 changed files with 41 additions and 9 deletions
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11
src/config/crypto/ConcreteInnerEncryptor.h
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@ -54,12 +54,13 @@ namespace cryfs {
boost::optional<cpputils::Data> ConcreteInnerEncryptor<Cipher>::_deserialize(const cpputils::Data &ciphertext) const {
cpputils::Deserializer deserializer(&ciphertext);
try {
_checkHeader(&deserializer);
std::string readCipherName = deserializer.readString();
if (readCipherName != _cipherName) {
cpputils::logging::LOG(cpputils::logging::ERROR) << "Wrong inner cipher used";
return boost::none;
}
auto result = deserializer.readData();
auto result = deserializer.readTailData();
deserializer.finished();
return result;
} catch (const std::exception &e) {
@ -78,10 +79,12 @@ namespace cryfs {
template<class Cipher>
cpputils::Data ConcreteInnerEncryptor<Cipher>::_serialize(const cpputils::Data &ciphertext) const {
try {
cpputils::Serializer serializer(cpputils::Serializer::StringSize(_cipherName)
+ cpputils::Serializer::DataSize(ciphertext));
cpputils::Serializer serializer(cpputils::Serializer::StringSize(HEADER)
+ cpputils::Serializer::StringSize(_cipherName)
+ ciphertext.size());
serializer.writeString(HEADER);
serializer.writeString(_cipherName);
serializer.writeData(ciphertext);
serializer.writeTailData(ciphertext);
return serializer.finished();
} catch (const std::exception &e) {
cpputils::logging::LOG(cpputils::logging::ERROR) << "Error serializing inner configuration: " << e.what();

8
src/config/crypto/CryConfigEncryptor.cpp
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@ -11,7 +11,7 @@ using boost::none;
using namespace cpputils::logging;
namespace cryfs {
const string CryConfigEncryptor::HEADER = "cryfs.config;0.8.1;scrypt";
const string CryConfigEncryptor::HEADER = "cryfs.config;0;scrypt";
CryConfigEncryptor::CryConfigEncryptor(unique_ref<InnerEncryptor> innerEncryptor, OuterCipher::EncryptionKey outerKey, DerivedKeyConfig keyConfig)
: _innerEncryptor(std::move(innerEncryptor)), _outerKey(std::move(outerKey)), _keyConfig(std::move(keyConfig)) {
@ -39,10 +39,10 @@ namespace cryfs {
try {
Serializer serializer(Serializer::StringSize(HEADER)
+ _keyConfig.serializedSize()
+ Serializer::DataSize(ciphertext));
+ ciphertext.size());
writeHeader(&serializer);
_keyConfig.serialize(&serializer);
serializer.writeData(ciphertext);
serializer.writeTailData(ciphertext);
return serializer.finished();
} catch (const std::exception &e) {
cpputils::logging::LOG(cpputils::logging::ERROR) << "Error serializing CryConfigEncryptor: " << e.what();
@ -69,7 +69,7 @@ namespace cryfs {
}
optional<Data> CryConfigEncryptor::_loadAndDecryptConfigData(Deserializer *deserializer) {
auto ciphertext = deserializer->readData();
auto ciphertext = deserializer->readTailData();
auto inner = OuterCipher::decrypt(static_cast<const uint8_t*>(ciphertext.data()), ciphertext.size(), _outerKey);
if(inner == none) {
return none;

22
src/config/crypto/InnerEncryptor.cpp
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@ -1 +1,21 @@
#include "InnerEncryptor.h"
#include "InnerEncryptor.h"
using std::string;
using cpputils::Deserializer;
using cpputils::Serializer;
namespace cryfs {
const string InnerEncryptor::HEADER = "cryfs.config.inner;0";
void InnerEncryptor::_checkHeader(Deserializer *deserializer) {
string header = deserializer->readString();
if (header != HEADER) {
throw std::runtime_error("Invalid header");
}
}
void InnerEncryptor::_writeHeader(Serializer *serializer) {
serializer->writeString(HEADER);
}
}

9
src/config/crypto/InnerEncryptor.h
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@ -5,12 +5,21 @@
#include <messmer/cpp-utils/data/Data.h>
#include <messmer/cpp-utils/pointer/unique_ref.h>
#include <boost/optional.hpp>
#include <messmer/cpp-utils/data/Deserializer.h>
#include <messmer/cpp-utils/data/Serializer.h>
namespace cryfs {
class InnerEncryptor {
public:
virtual cpputils::Data encrypt(const cpputils::Data &plaintext) const = 0;
virtual boost::optional <cpputils::Data> decrypt(const cpputils::Data &plaintext) const = 0;
protected:
static void _checkHeader(cpputils::Deserializer *deserializer);
static void _writeHeader(cpputils::Serializer *serializer);
private:
static const std::string HEADER;
};
}