diff --git a/ChangeLog.txt b/ChangeLog.txt
index 69451c10..26b82937 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -4,3 +4,6 @@ Version 0.8.1
 * Password Encryption: If the configuration file is not specified as command line parameter, it will be put into the base directory. The filesystem can be mounted with the password only, without specifying a config file on command line.
 * Logfiles: Added a --logfile option to specify where logs should be written to. If the option is not specified, CryFs logs to syslog.
 * Running in Background: Fixed daemonization. When CryFs is run without "-f" flag, it will run in background.
+* Better error messages when base directory is not existing, not readable or not writeable.
+* Allow --cipher=xxx to specify cipher on command line. If cryfs is creating a new filesystem, it will use this cipher. If it is opening an existing filesystem, it will check whether this is the cipher used by it.
+* --show-ciphers shows a list of all supported ciphers
\ No newline at end of file
diff --git a/src/Cli.cpp b/src/Cli.cpp
index dd5e9278..be901ae6 100644
--- a/src/Cli.cpp
+++ b/src/Cli.cpp
@@ -102,7 +102,7 @@ namespace cryfs {
             auto console = make_unique_ref<IOStreamConsole>();
             auto &keyGenerator = Random::OSRandom();
             std::cout << "Loading config file..." << std::endl;
-            auto config = CryConfigLoader(std::move(console), keyGenerator, &Cli::_askPassword).loadOrCreate(configFile);
+            auto config = CryConfigLoader(std::move(console), keyGenerator, &Cli::_askPassword, options.cipher()).loadOrCreate(configFile);
             std::cout << "Loading config file...done" << std::endl;
             if (config == none) {
                 std::cerr << "Could not load config file. Did you enter the correct password?" << std::endl;
@@ -218,7 +218,7 @@ namespace cryfs {
         cpputils::showBacktraceOnSigSegv();
         _showVersion();
 
-        ProgramOptions options = program_options::Parser(argc, argv).parse();
+        ProgramOptions options = program_options::Parser(argc, argv).parse(CryCiphers::supportedCipherNames());
 
         try {
             _sanityChecks(options);
diff --git a/src/config/CryConfigCreator.cpp b/src/config/CryConfigCreator.cpp
index 2ed33493..61a1bdb1 100644
--- a/src/config/CryConfigCreator.cpp
+++ b/src/config/CryConfigCreator.cpp
@@ -6,21 +6,33 @@ using cpputils::unique_ref;
 using cpputils::RandomGenerator;
 using std::string;
 using std::vector;
+using boost::optional;
+using boost::none;
+
 namespace cryfs {
 
     CryConfigCreator::CryConfigCreator(unique_ref<Console> console, RandomGenerator &encryptionKeyGenerator)
         :_console(std::move(console)), _encryptionKeyGenerator(encryptionKeyGenerator) {
     }
 
-    CryConfig CryConfigCreator::create() {
+    CryConfig CryConfigCreator::create(const optional<string> &cipher) {
         CryConfig config;
-        config.SetCipher(_generateCipher());
+        config.SetCipher(_generateCipher(cipher));
         config.SetEncryptionKey(_generateEncKey(config.Cipher()));
         config.SetRootBlob(_generateRootBlobKey());
         return config;
     }
 
-    string CryConfigCreator::_generateCipher() {
+    string CryConfigCreator::_generateCipher(const optional<string> &cipher) {
+        if (cipher != none) {
+            ASSERT(std::find(CryCiphers::supportedCipherNames().begin(), CryCiphers::supportedCipherNames().end(), *cipher) != CryCiphers::supportedCipherNames().end(), "Invalid cipher");
+            return *cipher;
+        } else {
+            return _askCipher();
+        }
+    }
+
+    string CryConfigCreator::_askCipher() {
         vector<string> ciphers = CryCiphers::supportedCipherNames();
         string cipherName = "";
         bool askAgain = true;
diff --git a/src/config/CryConfigCreator.h b/src/config/CryConfigCreator.h
index 66731b46..ecc92123 100644
--- a/src/config/CryConfigCreator.h
+++ b/src/config/CryConfigCreator.h
@@ -13,9 +13,10 @@ namespace cryfs {
         CryConfigCreator(cpputils::unique_ref<cpputils::Console> console, cpputils::RandomGenerator &encryptionKeyGenerator);
         CryConfigCreator(CryConfigCreator &&rhs) = default;
 
-        CryConfig create();
+        CryConfig create(const boost::optional<std::string> &cipher);
     private:
-        std::string _generateCipher();
+        std::string _generateCipher(const boost::optional<std::string> &cipher);
+        std::string _askCipher();
         std::string _generateEncKey(const std::string &cipher);
         std::string _generateRootBlobKey();
         bool _showWarningForCipherAndReturnIfOk(const std::string &cipherName);
diff --git a/src/config/CryConfigLoader.cpp b/src/config/CryConfigLoader.cpp
index 1fbe3a82..a47299a5 100644
--- a/src/config/CryConfigLoader.cpp
+++ b/src/config/CryConfigLoader.cpp
@@ -20,8 +20,8 @@ using namespace cpputils::logging;
 
 namespace cryfs {
 
-CryConfigLoader::CryConfigLoader(unique_ref<Console> console, RandomGenerator &keyGenerator, function<string()> askPassword)
-    : _creator(std::move(console), keyGenerator), _askPassword(askPassword) {
+CryConfigLoader::CryConfigLoader(unique_ref<Console> console, RandomGenerator &keyGenerator, function<string()> askPassword, const optional<string> &cipher)
+    : _creator(std::move(console), keyGenerator), _askPassword(askPassword), _cipher(cipher) {
 }
 
 optional<CryConfigFile> CryConfigLoader::_loadConfig(const bf::path &filename) {
@@ -31,6 +31,9 @@ optional<CryConfigFile> CryConfigLoader::_loadConfig(const bf::path &filename) {
     LOG(ERROR) << "Could not load config file. Wrong password?";
     return none;
   }
+  if (_cipher != none && config->config()->Cipher() != *_cipher) {
+    throw std::runtime_error("Filesystem uses "+config->config()->Cipher()+" cipher and not "+*_cipher+" as specified.");
+  }
   return std::move(*config);
 }
 
diff --git a/src/config/CryConfigLoader.h b/src/config/CryConfigLoader.h
index 634f38ef..062495ec 100644
--- a/src/config/CryConfigLoader.h
+++ b/src/config/CryConfigLoader.h
@@ -13,7 +13,7 @@ namespace cryfs {
 
 class CryConfigLoader {
 public:
-  CryConfigLoader(cpputils::unique_ref<cpputils::Console> console, cpputils::RandomGenerator &keyGenerator, std::function<std::string()> askPassword);
+  CryConfigLoader(cpputils::unique_ref<cpputils::Console> console, cpputils::RandomGenerator &keyGenerator, std::function<std::string()> askPassword, const boost::optional<std::string> &cipher);
   CryConfigLoader(CryConfigLoader &&rhs) = default;
 
   template<class SCryptSettings = cpputils::SCryptDefaultSettings>
@@ -26,6 +26,7 @@ private:
 
     CryConfigCreator _creator;
     std::function<std::string()> _askPassword;
+    boost::optional<std::string> _cipher;
 
     DISALLOW_COPY_AND_ASSIGN(CryConfigLoader);
 };
@@ -41,7 +42,7 @@ boost::optional<CryConfigFile> CryConfigLoader::loadOrCreate(const boost::filesy
 
 template<class SCryptSettings>
 CryConfigFile CryConfigLoader::_createConfig(const boost::filesystem::path &filename) {
-    auto config = _creator.create();
+    auto config = _creator.create(_cipher);
     //TODO Ask confirmation if using insecure password (<8 characters)
     std::string password = _askPassword();
     return CryConfigFile::create<SCryptSettings>(filename, std::move(config), password);
diff --git a/src/program_options/Parser.cpp b/src/program_options/Parser.cpp
index df49b4ad..8caf859c 100644
--- a/src/program_options/Parser.cpp
+++ b/src/program_options/Parser.cpp
@@ -13,7 +13,9 @@ using std::string;
 using boost::optional;
 using boost::none;
 
-Parser::Parser(int argc, char *argv[]) :_options(_argsToVector(argc, argv)) {}
+Parser::Parser(int argc, char *argv[])
+        :_options(_argsToVector(argc, argv)) {
+}
 
 vector<char*> Parser::_argsToVector(int argc, char *argv[]) {
     vector<char*> result;
@@ -23,9 +25,9 @@ vector<char*> Parser::_argsToVector(int argc, char *argv[]) {
     return result;
 }
 
-ProgramOptions Parser::parse() const {
+ProgramOptions Parser::parse(const vector<string> &supportedCiphers) const {
     pair<vector<char*>, vector<char*>> options = splitAtDoubleDash(_options);
-    po::variables_map vm = _parseOptionsOrShowHelp(options.first);
+    po::variables_map vm = _parseOptionsOrShowHelp(options.first, supportedCiphers);
 
     string baseDir = vm["base-dir"].as<string>();
     string mountDir = vm["mount-dir"].as<string>();
@@ -38,19 +40,31 @@ ProgramOptions Parser::parse() const {
     if (vm.count("logfile")) {
         logfile = vm["logfile"].as<string>();
     }
+    optional<string> cipher = none;
+    if (vm.count("cipher")) {
+        cipher = vm["cipher"].as<string>();
+        _checkValidCipher(*cipher, supportedCiphers);
+    }
 
-    return ProgramOptions(baseDir, mountDir, configfile, foreground, logfile, options.second);
+    return ProgramOptions(baseDir, mountDir, configfile, foreground, logfile, cipher, options.second);
 }
 
-po::variables_map Parser::_parseOptionsOrShowHelp(const vector<char*> options) {
+void Parser::_checkValidCipher(const string &cipher, const vector<string> &supportedCiphers) {
+    if (std::find(supportedCiphers.begin(), supportedCiphers.end(), cipher) == supportedCiphers.end()) {
+        std::cerr << "Invalid cipher: " << cipher << std::endl;
+        exit(1);
+    }
+}
+
+po::variables_map Parser::_parseOptionsOrShowHelp(const vector<char*> options, const vector<string> &supportedCiphers) {
     try {
-        return _parseOptions(options);
+        return _parseOptions(options, supportedCiphers);
     } catch(const std::exception &e) {
         _showHelpAndExit();
     }
 }
 
-po::variables_map Parser::_parseOptions(const vector<char*> options) {
+po::variables_map Parser::_parseOptions(const vector<char*> options, const vector<string> &supportedCiphers) {
     po::options_description desc;
     po::positional_options_description positional_desc;
     _addAllowedOptions(&desc);
@@ -62,6 +76,9 @@ po::variables_map Parser::_parseOptions(const vector<char*> options) {
     if (vm.count("help")) {
         _showHelpAndExit();
     }
+    if (vm.count("show-ciphers")) {
+        _showCiphersAndExit(supportedCiphers);
+    }
     po::notify(vm);
 
     return vm;
@@ -73,6 +90,8 @@ void Parser::_addAllowedOptions(po::options_description *desc) {
             ("help,h", "show help message")
             ("config,c", po::value<string>(), "Configuration file")
             ("foreground,f", "Run CryFS in foreground.")
+            ("cipher", po::value<string>(), "Cipher to use for encryption. See possible values by calling cryfs with --show-ciphers")
+            ("show-ciphers", "Show list of supported ciphers.")
             ("logfile", po::value<string>(), "Specify the file to write log messages to. If this is not specified, log messages will go to stdout, or syslog if CryFS is running in the background.")
             ;
     desc->add(options);
@@ -89,6 +108,13 @@ void Parser::_addPositionalOptionForBaseDir(po::options_description *desc, po::p
     desc->add(hidden);
 }
 
+[[noreturn]] void Parser::_showCiphersAndExit(const vector<string> &supportedCiphers) {
+    for (const auto &cipher : supportedCiphers) {
+        std::cerr << cipher << "\n";
+    }
+    exit(0);
+}
+
 [[noreturn]] void Parser::_showHelpAndExit() {
     cerr << "Usage: cryfs [options] rootDir mountPoint [-- [FUSE Mount Options]]\n";
     po::options_description desc;
diff --git a/src/program_options/Parser.h b/src/program_options/Parser.h
index 852686a4..c884cda1 100644
--- a/src/program_options/Parser.h
+++ b/src/program_options/Parser.h
@@ -11,7 +11,7 @@ namespace cryfs {
         public:
             Parser(int argc, char *argv[]);
 
-            ProgramOptions parse() const;
+            ProgramOptions parse(const std::vector<std::string> &supportedCiphers) const;
 
         private:
             static std::vector<char *> _argsToVector(int argc, char *argv[]);
@@ -19,8 +19,10 @@ namespace cryfs {
             static void _addPositionalOptionForBaseDir(boost::program_options::options_description *desc,
                                                        boost::program_options::positional_options_description *positional);
             [[noreturn]] static void _showHelpAndExit();
-            static boost::program_options::variables_map _parseOptionsOrShowHelp(const std::vector<char*> options);
-            static boost::program_options::variables_map _parseOptions(const std::vector<char*> options);
+            [[noreturn]] static void _showCiphersAndExit(const std::vector<std::string> &supportedCiphers);
+            static boost::program_options::variables_map _parseOptionsOrShowHelp(const std::vector<char*> options, const std::vector<std::string> &supportedCiphers);
+            static boost::program_options::variables_map _parseOptions(const std::vector<char*> options, const std::vector<std::string> &supportedCiphers);
+            static void _checkValidCipher(const std::string &cipher, const std::vector<std::string> &supportedCiphers);
 
             std::vector<char*> _options;
         };
diff --git a/src/program_options/ProgramOptions.cpp b/src/program_options/ProgramOptions.cpp
index 7d5ac080..d7bca823 100644
--- a/src/program_options/ProgramOptions.cpp
+++ b/src/program_options/ProgramOptions.cpp
@@ -8,9 +8,10 @@ using std::vector;
 using boost::optional;
 
 ProgramOptions::ProgramOptions(const string &baseDir, const string &mountDir, const optional<string> &configFile,
-                               bool foreground, const optional<string> &logFile, const vector<char*> &fuseOptions)
+                               bool foreground, const optional<string> &logFile, const optional<string> &cipher,
+                               const vector<char*> &fuseOptions)
     :_baseDir(baseDir), _mountDir(new char[mountDir.size()+1]), _configFile(configFile), _foreground(foreground),
-     _logFile(logFile), _fuseOptions(fuseOptions) {
+     _logFile(logFile), _cipher(cipher), _fuseOptions(fuseOptions) {
     std::memcpy(_mountDir, mountDir.c_str(), mountDir.size()+1);
     // Fuse needs the mountDir passed as first option (first option = position 1, since 0 is the executable name)
     ASSERT(_fuseOptions.size() >= 1, "There has to be one parameter at least for the executable name");
@@ -50,6 +51,10 @@ const optional<string> &ProgramOptions::logFile() const {
     return _logFile;
 }
 
+const optional<string> &ProgramOptions::cipher() const {
+    return _cipher;
+}
+
 const vector<char *> &ProgramOptions::fuseOptions() const {
     return _fuseOptions;
 }
diff --git a/src/program_options/ProgramOptions.h b/src/program_options/ProgramOptions.h
index f242fd52..113777f2 100644
--- a/src/program_options/ProgramOptions.h
+++ b/src/program_options/ProgramOptions.h
@@ -12,7 +12,7 @@ namespace cryfs {
         class ProgramOptions final {
         public:
             ProgramOptions(const std::string &baseDir, const std::string &mountDir, const boost::optional<std::string> &configFile,
-                           bool foreground, const boost::optional<std::string> &logFile,
+                           bool foreground, const boost::optional<std::string> &logFile, const boost::optional<std::string> &cipher,
                            const std::vector<char *> &fuseOptions);
             ProgramOptions(ProgramOptions &&rhs);
             ~ProgramOptions();
@@ -22,6 +22,7 @@ namespace cryfs {
             const boost::optional<std::string> &configFile() const;
             bool foreground() const;
             const boost::optional<std::string> &logFile() const;
+            const boost::optional<std::string> &cipher() const;
             const std::vector<char *> &fuseOptions() const;
 
         private:
@@ -30,6 +31,7 @@ namespace cryfs {
             boost::optional<std::string> _configFile;
             bool _foreground;
             boost::optional<std::string> _logFile;
+            boost::optional<std::string> _cipher;
             std::vector<char *> _fuseOptions;
 
             DISALLOW_COPY_AND_ASSIGN(ProgramOptions);
diff --git a/test/cli/CliTest_Setup.cpp b/test/cli/CliTest_Setup.cpp
index 33a429a9..3012178e 100644
--- a/test/cli/CliTest_Setup.cpp
+++ b/test/cli/CliTest_Setup.cpp
@@ -6,24 +6,24 @@ using cpputils::TempFile;
 using CliTest_Setup = CliTest;
 
 TEST_F(CliTest_Setup, NoSpecialOptions) {
-    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str()});
+    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str(), "--cipher", "aes-256-gcm"}, basedir);
 }
 
 TEST_F(CliTest_Setup, NotexistingLogfileGiven) {
     TempFile notexisting_logfile(false);
-    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str(), "--logfile", notexisting_logfile.path().c_str()});
+    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str(), "--logfile", notexisting_logfile.path().c_str()}, basedir);
     //TODO Expect logfile is used (check logfile content)
 }
 
 TEST_F(CliTest_Setup, ExistingLogfileGiven) {
-    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str(), "--logfile", logfile.path().c_str()});
+    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str(), "--logfile", logfile.path().c_str()}, basedir);
     //TODO Expect logfile is used (check logfile content)
 }
 
 TEST_F(CliTest_Setup, ConfigfileGiven) {
-    EXPECT_RUN_SUCCESS({basedir.c_str(), "--config", configfile.path().c_str(), mountdir.c_str()});
+    EXPECT_RUN_SUCCESS({basedir.c_str(), "--config", configfile.path().c_str(), mountdir.c_str()}, basedir);
 }
 
 TEST_F(CliTest_Setup, FuseOptionGiven) {
-    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str(), "--", "-f"});
+    EXPECT_RUN_SUCCESS({basedir.c_str(), mountdir.c_str(), "--", "-f"}, basedir);
 }
\ No newline at end of file
diff --git a/test/cli/CliTest_WrongEnvironment.cpp b/test/cli/CliTest_WrongEnvironment.cpp
index 87a02995..235a28b8 100644
--- a/test/cli/CliTest_WrongEnvironment.cpp
+++ b/test/cli/CliTest_WrongEnvironment.cpp
@@ -43,7 +43,7 @@ public:
     }
 
     void Test_Run_Success() {
-        EXPECT_RUN_SUCCESS(args());
+        EXPECT_RUN_SUCCESS(args(), basedir);
     }
 
     void Test_Run_Error(const char *expectedError) {
diff --git a/test/cli/testutils/CliTest.h b/test/cli/testutils/CliTest.h
index 46b811f5..efdaa31a 100644
--- a/test/cli/testutils/CliTest.h
+++ b/test/cli/testutils/CliTest.h
@@ -6,6 +6,7 @@
 #include <messmer/cpp-utils/tempfile/TempDir.h>
 #include <messmer/cpp-utils/tempfile/TempFile.h>
 #include "../../../src/Cli.h"
+#include <messmer/cpp-utils/logging/logging.h>
 
 class CliTest : public ::testing::Test {
 public:
@@ -40,14 +41,25 @@ public:
         );
     }
 
-    void EXPECT_RUN_SUCCESS(std::vector<const char*> args) {
-        //TODO
-        /*EXPECT_EXIT(
+    class _UnmountFilesystemInDestructor final {
+    public:
+        _UnmountFilesystemInDestructor(const boost::filesystem::path &baseDir) :_baseDir(baseDir) {}
+        ~_UnmountFilesystemInDestructor() {
+            if (0 != system((std::string("fusermount -u ")+_baseDir.c_str()).c_str()), "Could not unmount cryfs") {
+                cpputils::logging::LOG(cpputils::logging::ERROR) << "Could not unmount cryfs";
+            }
+        }
+    private:
+        boost::filesystem::path _baseDir;
+    };
+
+    void EXPECT_RUN_SUCCESS(std::vector<const char*> args, const boost::filesystem::path &baseDir) {
+        /*_UnmountFilesystemInDestructor raii(baseDir);
+        EXPECT_EXIT(
             run(args),
             ::testing::ExitedWithCode(0),
             "Filesystem is running"
         );*/
-        //TODO Then stop running cryfs process again
     }
 };
 
diff --git a/test/config/CryConfigCreatorTest.cpp b/test/config/CryConfigCreatorTest.cpp
index 2badcaa1..c0523798 100644
--- a/test/config/CryConfigCreatorTest.cpp
+++ b/test/config/CryConfigCreatorTest.cpp
@@ -36,33 +36,38 @@ public:
 
 #define EXPECT_ASK_FOR_CIPHER() EXPECT_CALL(*console, ask(HasSubstr("block cipher"), UnorderedElementsAreArray(CryCiphers::supportedCipherNames())))
 
-TEST_F(CryConfigCreatorTest, DoesNotCrash) {
-    EXPECT_ASK_FOR_CIPHER().WillOnce(ChooseAnyCipher());
-    CryConfig config = creator.create();
+TEST_F(CryConfigCreatorTest, DoesAskForCipherIfNotSpecified) {
+    EXPECT_ASK_FOR_CIPHER().Times(1).WillOnce(ChooseAnyCipher());
+    CryConfig config = creator.create(none);
+}
+
+TEST_F(CryConfigCreatorTest, DoesNotAskForCipherIfSpecified) {
+    EXPECT_ASK_FOR_CIPHER().Times(0);
+    CryConfig config = creator.create(string("aes-256-gcm"));
 }
 
 TEST_F(CryConfigCreatorTest, ChoosesEmptyRootBlobId) {
     EXPECT_ASK_FOR_CIPHER().WillOnce(ChooseAnyCipher());
-    CryConfig config = creator.create();
+    CryConfig config = creator.create(none);
     EXPECT_EQ("", config.RootBlob()); // This tells CryFS to create a new root blob
 }
 
 TEST_F(CryConfigCreatorTest, ChoosesValidEncryptionKey_448) {
     EXPECT_ASK_FOR_CIPHER().WillOnce(ChooseCipher("mars-448-gcm"));
-    CryConfig config = creator.create();
+    CryConfig config = creator.create(none);
     cpputils::Mars448_GCM::EncryptionKey::FromString(config.EncryptionKey()); // This crashes if invalid
 }
 
 TEST_F(CryConfigCreatorTest, ChoosesValidEncryptionKey_256) {
     EXPECT_ASK_FOR_CIPHER().WillOnce(ChooseCipher("aes-256-gcm"));
-    CryConfig config = creator.create();
-cpputils::AES256_GCM::EncryptionKey::FromString(config.EncryptionKey()); // This crashes if invalid
+    CryConfig config = creator.create(none);
+    cpputils::AES256_GCM::EncryptionKey::FromString(config.EncryptionKey()); // This crashes if invalid
 }
 
 TEST_F(CryConfigCreatorTest, ChoosesValidEncryptionKey_128) {
     EXPECT_ASK_FOR_CIPHER().WillOnce(ChooseCipher("aes-128-gcm"));
-    CryConfig config = creator.create();
-cpputils::AES128_GCM::EncryptionKey::FromString(config.EncryptionKey()); // This crashes if invalid
+    CryConfig config = creator.create(none);
+    cpputils::AES128_GCM::EncryptionKey::FromString(config.EncryptionKey()); // This crashes if invalid
 }
 
 class CryConfigCreatorTest_ChooseCipher: public CryConfigCreatorTest, public ::testing::WithParamInterface<string> {
@@ -88,7 +93,7 @@ TEST_P(CryConfigCreatorTest_ChooseCipher, ChoosesCipherCorrectly) {
 
     EXPECT_ASK_FOR_CIPHER().WillOnce(ChooseCipher(cipherName));
 
-    CryConfig config = creator.create();
+    CryConfig config = creator.create(none);
     EXPECT_EQ(cipherName, config.Cipher());
 }
 
diff --git a/test/config/CryConfigLoaderTest.cpp b/test/config/CryConfigLoaderTest.cpp
index b99be336..3062906d 100644
--- a/test/config/CryConfigLoaderTest.cpp
+++ b/test/config/CryConfigLoaderTest.cpp
@@ -17,22 +17,24 @@ using ::testing::_;
 
 using namespace cryfs;
 
+//TODO Test loading with same/different --cipher argument
+
 class CryConfigLoaderTest: public ::testing::Test, public TestWithMockConsole {
 public:
     CryConfigLoaderTest(): file(false) {}
 
-    CryConfigLoader loader(const string &password) {
-        return CryConfigLoader(mockConsole(), cpputils::Random::PseudoRandom(), [password] {return password;});
+    CryConfigLoader loader(const string &password, const optional<string> &cipher = none) {
+        return CryConfigLoader(mockConsole(), cpputils::Random::PseudoRandom(), [password] {return password;}, cipher);
     }
 
-    CryConfigFile Create(const string &password = "mypassword") {
+    CryConfigFile Create(const string &password = "mypassword", const optional<string> &cipher = none) {
         EXPECT_FALSE(file.exists());
-        return loader(password).loadOrCreate<SCryptTestSettings>(file.path()).value();
+        return loader(password, cipher).loadOrCreate<SCryptTestSettings>(file.path()).value();
     }
 
-    optional<CryConfigFile> Load(const string &password = "mypassword") {
+    optional<CryConfigFile> Load(const string &password = "mypassword", const optional<string> &cipher = none) {
         EXPECT_TRUE(file.exists());
-        return loader(password).loadOrCreate<SCryptTestSettings>(file.path());
+        return loader(password, cipher).loadOrCreate<SCryptTestSettings>(file.path());
     }
 
     void CreateWithRootBlob(const string &rootBlob, const string &password = "mypassword") {
@@ -73,6 +75,21 @@ TEST_F(CryConfigLoaderTest, DoesntLoadIfWrongPassword) {
     EXPECT_EQ(none, loaded);
 }
 
+TEST_F(CryConfigLoaderTest, DoesntLoadIfDifferentCipher) {
+    Create("mypassword", string("aes-256-gcm"));
+    try {
+        Load("mypassword", string("aes-256-cfb"));
+        EXPECT_TRUE(false); // Should throw exception
+    } catch (const std::runtime_error &e) {
+        EXPECT_EQ(string("Filesystem uses aes-256-gcm cipher and not aes-256-cfb as specified."), e.what());
+    }
+}
+
+TEST_F(CryConfigLoaderTest, DoesLoadIfSameCipher) {
+    Create("mypassword", string("aes-256-gcm"));
+    Load("mypassword", string("aes-256-gcm"));
+}
+
 TEST_F(CryConfigLoaderTest, RootBlob_Load) {
     CreateWithRootBlob("rootblobid");
     auto loaded = Load().value();
diff --git a/test/filesystem/CryFsTest.cpp b/test/filesystem/CryFsTest.cpp
index fdf06e9b..cea3fa93 100644
--- a/test/filesystem/CryFsTest.cpp
+++ b/test/filesystem/CryFsTest.cpp
@@ -23,6 +23,7 @@ using cpputils::unique_ref;
 using cpputils::Console;
 using cpputils::Random;
 using blockstore::ondisk::OnDiskBlockStore;
+using boost::none;
 
 namespace bf = boost::filesystem;
 using namespace cryfs;
@@ -33,7 +34,7 @@ public:
   }
 
   CryConfigFile loadOrCreateConfig() {
-    return CryConfigLoader(mockConsole(), Random::PseudoRandom(), [] {return "mypassword";}).loadOrCreate(config.path()).value();
+    return CryConfigLoader(mockConsole(), Random::PseudoRandom(), [] {return "mypassword";}, none).loadOrCreate(config.path()).value();
   }
 
   unique_ref<OnDiskBlockStore> blockStore() {
diff --git a/test/filesystem/FileSystemTest.cpp b/test/filesystem/FileSystemTest.cpp
index 62e9114d..2552f3c6 100644
--- a/test/filesystem/FileSystemTest.cpp
+++ b/test/filesystem/FileSystemTest.cpp
@@ -13,6 +13,7 @@ using cpputils::Random;
 using fspp::Device;
 using ::testing::Return;
 using ::testing::_;
+using boost::none;
 
 using blockstore::testfake::FakeBlockStore;
 
@@ -26,7 +27,7 @@ public:
 
   unique_ref<Device> createDevice() override {
     auto blockStore = cpputils::make_unique_ref<FakeBlockStore>();
-    auto config = CryConfigLoader(mockConsole(), Random::PseudoRandom(), [] {return "mypassword";})
+    auto config = CryConfigLoader(mockConsole(), Random::PseudoRandom(), [] {return "mypassword";}, none)
             .loadOrCreate(configFile.path()).value();
     return make_unique_ref<CryDevice>(std::move(config), std::move(blockStore));
   }
diff --git a/test/program_options/ParserTest.cpp b/test/program_options/ParserTest.cpp
index ea128cbd..0eb2d1df 100644
--- a/test/program_options/ParserTest.cpp
+++ b/test/program_options/ParserTest.cpp
@@ -1,6 +1,8 @@
 #include "testutils/ProgramOptionsTestBase.h"
 #include "../../src/program_options/Parser.h"
+#include "../../src/config/CryCipher.h"
 
+using namespace cryfs;
 using namespace cryfs::program_options;
 using std::vector;
 using boost::none;
@@ -9,7 +11,7 @@ class ProgramOptionsParserTest: public ProgramOptionsTestBase {
 public:
     ProgramOptions parse(std::initializer_list<const char*> options) {
         vector<char*> _options = ProgramOptionsTestBase::options(options);
-        return Parser(_options.size(), _options.data()).parse();
+        return Parser(_options.size(), _options.data()).parse(CryCiphers::supportedCipherNames());
     }
 };
 
@@ -29,18 +31,27 @@ TEST_F(ProgramOptionsParserTest, MissingDir) {
 
 TEST_F(ProgramOptionsParserTest, HelpLongOption) {
     EXPECT_DEATH(
-            parse({"./myExecutable", "--help"}),
-    "Usage:"
+        parse({"./myExecutable", "--help"}),
+        "Usage:"
     );
 }
 
 TEST_F(ProgramOptionsParserTest, HelpShortOption) {
     EXPECT_DEATH(
-            parse({"./myExecutable", "-h"}),
-    "Usage:"
+        parse({"./myExecutable", "-h"}),
+        "Usage:"
     );
 }
 
+TEST_F(ProgramOptionsParserTest, ShowCiphers) {
+    EXPECT_EXIT(
+        parse({"./myExecutable", "--show-ciphers"}),
+        ::testing::ExitedWithCode(0),
+        "aes-256-gcm"
+    );
+}
+
+
 TEST_F(ProgramOptionsParserTest, NoSpecialOptions) {
     ProgramOptions options = parse({"./myExecutable", "/home/user/baseDir", "/home/user/mountDir"});
     EXPECT_EQ("/home/user/baseDir", options.baseDir());
@@ -60,6 +71,18 @@ TEST_F(ProgramOptionsParserTest, ConfigfileGiven) {
     EXPECT_EQ("/home/user/myconfigfile", options.configFile().value());
 }
 
+TEST_F(ProgramOptionsParserTest, CipherGiven) {
+    ProgramOptions options = parse({"./myExecutable", "/home/user/baseDir", "--cipher", "aes-256-gcm", "/home/user/mountDir"});
+    EXPECT_EQ("aes-256-gcm", options.cipher().value());
+}
+
+TEST_F(ProgramOptionsParserTest, InvalidCipher) {
+    EXPECT_DEATH(
+        parse({"./myExecutable", "/home/user/baseDir", "--cipher", "invalid-cipher", "/home/user/mountDir"}),
+        "Invalid cipher: invalid-cipher"
+    );
+}
+
 TEST_F(ProgramOptionsParserTest, FuseOptionGiven) {
     ProgramOptions options = parse({"./myExecutable", "/home/user/baseDir", "/home/user/mountDir", "--", "-f"});
     EXPECT_EQ("/home/user/baseDir", options.baseDir());
diff --git a/test/program_options/ProgramOptionsTest.cpp b/test/program_options/ProgramOptionsTest.cpp
index 46a48803..1375a192 100644
--- a/test/program_options/ProgramOptionsTest.cpp
+++ b/test/program_options/ProgramOptionsTest.cpp
@@ -10,53 +10,63 @@ using std::string;
 class ProgramOptionsTest: public ProgramOptionsTestBase {};
 
 TEST_F(ProgramOptionsTest, BaseDir) {
-    ProgramOptions testobj("/home/user/mydir", "", none, false, none, options({"./myExecutable"}));
+    ProgramOptions testobj("/home/user/mydir", "", none, false, none, none, options({"./myExecutable"}));
     EXPECT_EQ("/home/user/mydir", testobj.baseDir());
 }
 
 TEST_F(ProgramOptionsTest, MountDir) {
-    ProgramOptions testobj("", "/home/user/mydir", none, false, none, options({"./myExecutable"}));
+    ProgramOptions testobj("", "/home/user/mydir", none, false, none, none, options({"./myExecutable"}));
     EXPECT_EQ("/home/user/mydir", testobj.mountDir());
 }
 
 TEST_F(ProgramOptionsTest, ConfigfileNone) {
-    ProgramOptions testobj("", "", none, true, none, options({"./myExecutable"}));
+    ProgramOptions testobj("", "", none, true, none, none, options({"./myExecutable"}));
     EXPECT_EQ(none, testobj.configFile());
 }
 
 TEST_F(ProgramOptionsTest, ConfigfileSome) {
-    ProgramOptions testobj("", "", string("/home/user/configfile"), true, none, options({"./myExecutable"}));
+    ProgramOptions testobj("", "", string("/home/user/configfile"), true, none, none, options({"./myExecutable"}));
     EXPECT_EQ("/home/user/configfile", testobj.configFile().get());
 }
 
 TEST_F(ProgramOptionsTest, ForegroundFalse) {
-    ProgramOptions testobj("", "", none, false, none, options({"./myExecutable"}));
+    ProgramOptions testobj("", "", none, false, none, none, options({"./myExecutable"}));
     EXPECT_FALSE(testobj.foreground());
 }
 
 TEST_F(ProgramOptionsTest, ForegroundTrue) {
-    ProgramOptions testobj("", "", none, true, none, options({"./myExecutable"}));
+    ProgramOptions testobj("", "", none, true, none, none, options({"./myExecutable"}));
     EXPECT_TRUE(testobj.foreground());
 }
 
 TEST_F(ProgramOptionsTest, LogfileNone) {
-    ProgramOptions testobj("", "", none, true, none, options({"./myExecutable"}));
+    ProgramOptions testobj("", "", none, true, none, none, options({"./myExecutable"}));
     EXPECT_EQ(none, testobj.logFile());
 }
 
 TEST_F(ProgramOptionsTest, LogfileSome) {
-    ProgramOptions testobj("", "", none, true, string("logfile"), options({"./myExecutable"}));
+    ProgramOptions testobj("", "", none, true, string("logfile"), none, options({"./myExecutable"}));
     EXPECT_EQ("logfile", testobj.logFile().get());
 }
 
+TEST_F(ProgramOptionsTest, CipherNone) {
+    ProgramOptions testobj("", "", none, true, none, none, options({"./myExecutable"}));
+    EXPECT_EQ(none, testobj.cipher());
+}
+
+TEST_F(ProgramOptionsTest, CipherSome) {
+    ProgramOptions testobj("", "", none, true, none, string("aes-256-gcm"), options({"./myExecutable"}));
+    EXPECT_EQ("aes-256-gcm", testobj.cipher().get());
+}
+
 TEST_F(ProgramOptionsTest, EmptyFuseOptions) {
-    ProgramOptions testobj("/rootDir", "/home/user/mydir", none, false, none, options({"./myExecutable"}));
+    ProgramOptions testobj("/rootDir", "/home/user/mydir", none, false, none, none, options({"./myExecutable"}));
     //Fuse should have the mount dir as first parameter
     EXPECT_VECTOR_EQ({"./myExecutable", "/home/user/mydir"}, testobj.fuseOptions());
 }
 
 TEST_F(ProgramOptionsTest, SomeFuseOptions) {
-    ProgramOptions testobj("/rootDir", "/home/user/mydir", none, false, none, options({"./myExecutable", "-f", "--longoption"}));
+    ProgramOptions testobj("/rootDir", "/home/user/mydir", none, false, none, none, options({"./myExecutable", "-f", "--longoption"}));
     //Fuse should have the mount dir as first parameter
     EXPECT_VECTOR_EQ({"./myExecutable", "/home/user/mydir", "-f", "--longoption"}, testobj.fuseOptions());
 }