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+#Device Certificate Manager
+
+##About
+
+The Device Certificate Manager (DCM) provides cryptography services (digital certificates and keys) for authentication and secure communication with another system.
+Please visit the following webpage for the details about the prerequsities and the usage: [https://developer.tizen.org/development/guides/native-application/security/device-certificate-manager](https://developer.tizen.org/development/guides/native-application/security/device-certificate-manager).
+
+##Architecture
+
+The DCM (tizen.org repository *platform/core/security/device-certificate-manager*) consists of two submodules: the client and the daemon.
+The client provides the public DCM API, while the daemon its implementation.
+The implementation is realized with the internal backend API (see the *dcm-daemon/dcm-backend-api.h* header file).
+Example implementations of this backend API may be found in the tizen.org separate repository: *platform/core/security/device-certificate-manager-backend*.
+The DCM backend repository provides two implementations:
+1) dedicated for the KONAI SE device,
+2) based on the OpenSSL and dedicated mainly for the testing purposes.
+Both of them are packed to the separate rpm packages (respectively with the *kse* or the *dummy* in names), that provide the *libdcm-backend-api.so* library with the DCM backend API implementation.
+The library is loaded dynamically by the DCM daemon at runtime.
+Although the DCM backend is not installed automatically with the DCM, it is required for proper work of the DCM and because of that it must be installed manually.
+Alternatively, the specific Tizen image may be configured to contain the chosen backend.
+
+###The KONAI SE backend
+
+The KONAI SE backend uses the *libkonaise.so* closed library in its implementation.
+In order to use this backend, the KONAI SE library must be installed in the system (and the KONAI SE must be connected to the device).
+
+###The OpenSSL backend
+
+The OpenSSL backend uses the open source OpenSSL library.
+The OpenSSL certificate chain is ordered inversely, compared to the SE certificate chain, therefore, the order of the chain must be reversed within the implementation.
+The difference in the cerificates ordering is the reason why the *backend* level of abstraction is needed (instead of using the SE libraries with the common API directly in the DCM daemon).
+
+##Adding a new backend (a new SE device)
+
+In order to support a new SE device in the DCM, a new backend API implementation must be developed, which means that the plugin developer must provide the  implemenation of the plugin header (*dcm-daemon/dcm-backend-api.h*).
+Such an implementation may be based on the KONAI SE implementation from the *platform/core/security/device-certificate-manager-backend* repository.
+The new implementation may be added to this public repository or provided in the separate git repository.
+The most important item is to implement the *libdcm-backend-api.so* library and to install it in the system.
+The DCM daemon does not need to be modified.
+
+##Testing
+
+There are currently four general testing applications and one KONAI SE specific tool:
+- *dcm_api_test*
+- *dcm_example_capi*
+- *dcm_example_client*
+- *dcm_test_cert_rewriter*
+All testing applications should be executed after implementing changes to the DCM or to the DCM backend repository.
+
+There is also one KONAI SE specific tool: *dcm_konaise_tool* used to test the KONAI SE backend implementation.
+The list of examples of execution of the *dcm_konaise_tool* is displayed after running the tool in the command line without any arguments.