security: Generate random block in Tpm.

Change-Id: Ia65d32802ed0ebc76605ae7975ea02f4c2db737d
security: Export/Import Identity from/into KeyChain

Change-Id: I757f51f1408cf08b9fb1b1927834889fd29c0231
security: Add doxygen comments

Change-Id: Ieafe4d13513e626d84ef9e621694f69844785018
security: Adjust unlocking TPM process.

Change-Id: Iee8787bb9aaa8e05fab9544bd35ce9fe31eecf29