SIC Password and API keys are stored in a plain text file

Hello mithun_laha ,

   Can you provide a brief example of what calls you're making in your code?  Is it the remote BR that is returning this failure?  

Hey mithun_laha ,

Did u set up WinSCP to connect to the SFTP server on the client environment where the SFTP server can be accessed remotely on the OS Cloud App?

you might have created a Direct Connection with your SFTP details like port number and host name to access the Smart Integration Connecter page. (System Pane)
u are using the Smart integration function to get stored information like SFTP password, user name, etc.
using the ApiLibrary.GetSmartIntegrationConfigValue("Key as String to get the password value").

and u are using a  BRApi.Utilities.ExecRemoteGatewayBusinessRule to retrieve the results.
As per my understanding,

A database connection additionally with the Direct connection needs to setup to connect OS Cloud app Client Environment.If you notice and try to compile your smart integration function. it will ask for a database gateway connection to compile your code.
In your 
BRApi.Utilities.ExecRemoteGatewayBusinessRule function u need to mention the database connection name as the remotehostname to get details from the direct connection on the remote client environment.

Dim remoteResults As RemoteRequestResultDto = BRApi.Utilities.ExecRemoteGatewayBusinessRule(si,smartintegrationBRName,Nothing,database connection gateway name, function name in Smart integration Function BR name,String.Empty,False,600)

If you have followed these steps and still facing an issue please check by hardcoding the credentials in the WinSCP session in your extensibility rules to check your connection. (I hope u have used the WinSCP.dll in the referenced assemblies). OR if you have issues connecting with the Smart integration function please check the SIC logs.

I am not an expert at this but I have connected to Amazon S3 using a direct connection before. a similar approach should work here.