diff --git a/biicode.conf b/biicode.conf
index 67280e2a..886c80b5 100644
--- a/biicode.conf
+++ b/biicode.conf
@@ -1,6 +1,7 @@
 # Biicode configuration file
 
 [requirements]
+	 google/gmock: 4
 	 google/gtest: 11
 	 messmer/blobstore: 1
 	 messmer/blockstore: 2
diff --git a/src/config/CryCipher.cpp b/src/config/CryCipher.cpp
index 40770bc6..a691e14b 100644
--- a/src/config/CryCipher.cpp
+++ b/src/config/CryCipher.cpp
@@ -45,7 +45,7 @@ private:
     optional<string> _warning;
 };
 
-const string INTEGRITY_WARNING = "This cipher does not ensure integrity.";
+const string CryCiphers::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 = {
diff --git a/src/config/CryCipher.h b/src/config/CryCipher.h
index d4349224..4f43a055 100644
--- a/src/config/CryCipher.h
+++ b/src/config/CryCipher.h
@@ -26,6 +26,8 @@ public:
     static const CryCipher& find(const std::string &cipherName);
 
 private:
+    static const std::string INTEGRITY_WARNING;
+
     static const std::vector<std::shared_ptr<CryCipher>> SUPPORTED_CIPHERS;
 };
 
diff --git a/src/config/CryConfigFile.cpp b/src/config/CryConfigFile.cpp
index 626f4ec2..9010c1be 100644
--- a/src/config/CryConfigFile.cpp
+++ b/src/config/CryConfigFile.cpp
@@ -11,6 +11,9 @@ namespace bf = boost::filesystem;
 namespace cryfs {
 
 CryConfigFile CryConfigFile::create(const bf::path &path, CryConfig config) {
+    if (bf::exists(path)) {
+        throw std::runtime_error("Config file exists already.");
+    }
     return CryConfigFile(path, std::move(config));
 }
 
diff --git a/test/config/CryCipherTest.cpp b/test/config/CryCipherTest.cpp
new file mode 100644
index 00000000..08998bb0
--- /dev/null
+++ b/test/config/CryCipherTest.cpp
@@ -0,0 +1,136 @@
+#include <google/gtest/gtest.h>
+#include <google/gmock/gmock.h>
+#include "../../src/config/CryCipher.h"
+#include <messmer/blockstore/implementations/encrypted/ciphers/ciphers.h>
+#include <messmer/cpp-utils/pointer/unique_ref_boost_optional_gtest_workaround.h>
+#include <messmer/blockstore/implementations/testfake/FakeBlockStore.h>
+#include <messmer/blockstore/implementations/encrypted/EncryptedBlockStore.h>
+#include <messmer/cpp-utils/data/DataFixture.h>
+
+using namespace cryfs;
+using namespace blockstore::encrypted;
+using namespace blockstore::testfake;
+using namespace blockstore;
+
+using std::initializer_list;
+using std::string;
+using std::vector;
+using std::find;
+using boost::none;
+using testing::MatchesRegex;
+using cpputils::DataFixture;
+using cpputils::Data;
+using cpputils::unique_ref;
+using cpputils::make_unique_ref;
+
+class CryCipherTest : public ::testing::Test {
+public:
+    void EXPECT_FINDS_CORRECT_CIPHERS(initializer_list<string> ciphers) {
+      for (const string & cipher : ciphers) {
+        EXPECT_FINDS_CORRECT_CIPHER(cipher);
+      }
+    }
+
+    void EXPECT_FINDS_CORRECT_CIPHER(const string &cipherName) {
+      EXPECT_EQ(cipherName, CryCiphers::find(cipherName).cipherName());
+    }
+
+    template<class ExpectedCipher>
+    void EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE(const string &cipherName) {
+        const auto &actualCipher = CryCiphers::find(cipherName);
+        Data dataFixture = DataFixture::generate(1024);
+        string encKey = ExpectedCipher::EncryptionKey::CreatePseudoRandom().ToString();
+        _EXPECT_ENCRYPTS_WITH_ACTUAL_BLOCKSTORE_DECRYPTS_CORRECTLY_WITH_EXPECTED_BLOCKSTORE<ExpectedCipher>(actualCipher, encKey, std::move(dataFixture));
+    }
+
+    template<class ExpectedCipher>
+    void _EXPECT_ENCRYPTS_WITH_ACTUAL_BLOCKSTORE_DECRYPTS_CORRECTLY_WITH_EXPECTED_BLOCKSTORE(const CryCipher &actualCipher, const std::string &encKey, Data dataFixture) {
+        blockstore::Key key = blockstore::Key::CreatePseudoRandom();
+        Data encrypted = _encryptUsingEncryptedBlockStoreWithCipher(actualCipher, encKey, key, dataFixture.copy());
+        Data decrypted = _decryptUsingEncryptedBlockStoreWithCipher<ExpectedCipher>(encKey, key, std::move(encrypted));
+        EXPECT_EQ(dataFixture, decrypted);
+    }
+
+    Data _encryptUsingEncryptedBlockStoreWithCipher(const CryCipher &cipher, const std::string &encKey, const blockstore::Key &key, Data data) {
+        unique_ref<FakeBlockStore> _baseStore = make_unique_ref<FakeBlockStore>();
+        FakeBlockStore *baseStore = _baseStore.get();
+        unique_ref<BlockStore> encryptedStore = cipher.createEncryptedBlockstore(std::move(_baseStore), encKey);
+        auto created = encryptedStore->tryCreate(key, std::move(data));
+        EXPECT_NE(none, created);
+        return _loadBlock(baseStore, key);
+    }
+
+    template<class Cipher>
+    Data _decryptUsingEncryptedBlockStoreWithCipher(const std::string &encKey, const blockstore::Key &key, Data data) {
+        unique_ref<FakeBlockStore> baseStore = make_unique_ref<FakeBlockStore>();
+        auto created = baseStore->tryCreate(key, std::move(data));
+        EXPECT_NE(none, created);
+        EncryptedBlockStore<Cipher> encryptedStore(std::move(baseStore), Cipher::EncryptionKey::FromString(encKey));
+        return _loadBlock(&encryptedStore, key);
+    }
+
+    Data _loadBlock(BlockStore *store, const blockstore::Key &key) {
+        auto block = store->load(key).value();
+        Data data(block->size());
+        std::memcpy(data.data(), block->data(), block->size());
+        return data;
+    }
+};
+
+TEST_F(CryCipherTest, FindsCorrectCipher) {
+  EXPECT_FINDS_CORRECT_CIPHERS({
+    "aes-256-gcm", "aes-256-cfb", "aes-256-gcm", "aes-256-cfb",
+    "twofish-256-gcm", "twofish-256-cfb", "twofish-256-gcm", "twofish-256-cfb",
+    "serpent-256-gcm", "serpent-256-cfb", "serpent-256-gcm", "serpent-256-cfb",
+    "cast-256-gcm", "cast-256-cfb",
+    "mars-448-gcm", "mars-448-cfb", "mars-256-gcm", "mars-256-cfb", "mars-256-gcm", "mars-256-cfb"
+  });
+}
+
+TEST_F(CryCipherTest, CreatesCorrectEncryptedBlockStore) {
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<AES256_GCM>("aes-256-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<AES256_CFB>("aes-256-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<AES128_GCM>("aes-128-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<AES128_CFB>("aes-128-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Twofish256_GCM>("twofish-256-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Twofish256_CFB>("twofish-256-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Twofish128_GCM>("twofish-128-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Twofish128_CFB>("twofish-128-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Serpent256_GCM>("serpent-256-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Serpent256_CFB>("serpent-256-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Serpent128_GCM>("serpent-128-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Serpent128_CFB>("serpent-128-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Cast256_GCM>("cast-256-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Cast256_CFB>("cast-256-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Mars448_GCM>("mars-448-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Mars448_CFB>("mars-448-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Mars256_GCM>("mars-256-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Mars256_CFB>("mars-256-cfb");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Mars128_GCM>("mars-128-gcm");
+    EXPECT_CREATES_CORRECT_ENCRYPTED_BLOCKSTORE<Mars128_CFB>("mars-128-cfb");
+}
+
+TEST_F(CryCipherTest, SupportedCipherNamesContainsACipher) {
+  vector<string> supportedCipherNames = CryCiphers::supportedCipherNames();
+  EXPECT_NE(supportedCipherNames.end(), find(supportedCipherNames.begin(), supportedCipherNames.end(), "aes-256-gcm"));
+}
+
+TEST_F(CryCipherTest, ThereIsACipherWithoutWarning) {
+    EXPECT_EQ(none, CryCiphers::find("aes-256-gcm").warning());
+}
+
+TEST_F(CryCipherTest, ThereIsACipherWithIntegrityWarning) {
+    EXPECT_THAT(CryCiphers::find("aes-256-cfb").warning().get(), MatchesRegex(".*integrity.*"));
+}
+
+TEST_F(CryCipherTest, EncryptionKeyHasCorrectSize_448) {
+    EXPECT_EQ(Mars448_GCM::EncryptionKey::STRING_LENGTH, CryCiphers::find("mars-448-gcm").createKey().size());
+}
+
+TEST_F(CryCipherTest, EncryptionKeyHasCorrectSize_256) {
+    EXPECT_EQ(AES256_GCM::EncryptionKey::STRING_LENGTH, CryCiphers::find("aes-256-gcm").createKey().size());
+}
+
+TEST_F(CryCipherTest, EncryptionKeyHasCorrectSize_128) {
+    EXPECT_EQ(AES128_GCM::EncryptionKey::STRING_LENGTH, CryCiphers::find("aes-128-gcm").createKey().size());
+}
diff --git a/test/filesystem/CryFsTest.cpp b/test/filesystem/CryFsTest.cpp
index 367ccc7a..906c0896 100644
--- a/test/filesystem/CryFsTest.cpp
+++ b/test/filesystem/CryFsTest.cpp
@@ -41,9 +41,9 @@ public:
 
 TEST_F(CryFsTest, CreatedRootdirIsLoadableAfterClosing) {
   {
-    CryDevice dev(CryConfigLoader().createNewWithWeakKey(config.path()), make_unique_ref<OnDiskBlockStore>(rootdir.path()));
+    CryDevice dev(CryConfigLoader().createNewForTest(config.path()), make_unique_ref<OnDiskBlockStore>(rootdir.path()));
   }
-  CryDevice dev(CryConfigLoader().loadExisting(config.path()).value(), make_unique_ref<OnDiskBlockStore>(rootdir.path()));
+  CryDevice dev(CryConfigFile::load(config.path()).value(), make_unique_ref<OnDiskBlockStore>(rootdir.path()));
   auto root = dev.Load(bf::path("/"));
   dynamic_pointer_move<CryDir>(root.get()).get()->children();
 }
@@ -52,7 +52,7 @@ TEST_F(CryFsTest, UsingStrongKey1_CreatedRootdirIsLoadableAfterClosing) {
   {
     CryDevice dev(CryConfigLoader(make_unique_ref<MockConsole>()).createNew(config.path()), make_unique_ref<OnDiskBlockStore>(rootdir.path()));
   }
-  CryDevice dev(CryConfigLoader().loadExisting(config.path()).value(), make_unique_ref<OnDiskBlockStore>(rootdir.path()));
+  CryDevice dev(CryConfigFile::load(config.path()).value(), make_unique_ref<OnDiskBlockStore>(rootdir.path()));
   auto root = dev.Load(bf::path("/"));
   dynamic_pointer_move<CryDir>(root.get()).get()->children();
 }
diff --git a/test/filesystem/FileSystemTest.cpp b/test/filesystem/FileSystemTest.cpp
index 4029e4f3..736c87c4 100644
--- a/test/filesystem/FileSystemTest.cpp
+++ b/test/filesystem/FileSystemTest.cpp
@@ -21,7 +21,7 @@ public:
 
   unique_ref<Device> createDevice() override {
     auto blockStore = cpputils::make_unique_ref<FakeBlockStore>();
-    auto config = CryConfigLoader().loadOrCreateWithWeakKey(configFile.path());
+    auto config = CryConfigLoader().loadOrCreateForTest(configFile.path());
     return make_unique_ref<CryDevice>(std::move(config), std::move(blockStore));
   }