Update README for handing GenerateCSR request
Change-Id: I2d8a7fd0bf3157936ac53fe3a48be8926b351334
Signed-off-by: Marri Devender Rao <devenrao@in.ibm.com>
diff --git a/xyz/openbmc_project/Certs/README.md b/xyz/openbmc_project/Certs/README.md
index 72144e5..45c79c7 100644
--- a/xyz/openbmc_project/Certs/README.md
+++ b/xyz/openbmc_project/Certs/README.md
@@ -93,6 +93,28 @@
private key, for the service which requirs certificate and key.
- CSR based Certificate validation is alway's based on private key in the system.
+### CSR Request
+- CSR requests initiated through D-Bus are time-consuming and might result
+ D-Bus time-out error.
+- To overcome the time-out error, parent process is forked and CSR operation
+ is performed in the child process so that parent process can return the
+ calling thread immediately.
+- OpenSSL library is used in generating CSR based on the algorithm type.
+- At present supporting generating CSR for only "RSA" algorithm type.
+- Parent process registers child process PID and a callback method in the
+ sd_event_lopp so that callback method is invoked upon completion
+ the CSR request in the child process.
+- Callback method invoked creates a CSR object with the status of the CSR
+ operation returned from the child process.
+- CSR read operation will return the CSR string if status is SUCCESS else throws
+ InternalFailure exception to the caller.
+- Certificate Manager implements "/xyz/openbmc_project/Certs/CSR/Create"
+ interface.
+- CSR object created implements "/xyz/openbmc_project/Certs/CSR" interface.
+- Caller needs to validate the CSR request parameters.
+- Caller need to wait on "InterfacesAdded" signal generated upon creation
+ of the CSR object to start reading CSR string.
+
### Example usage for the GenerateCSR POST request
```