In my application I have to store very sensitive data of its users, such as various password to other 3rd part services (user fill a form where he provides us login and password to 3rd part service)
The goal of the application is to setup other complex system using powershell scripts generated from over 100 inputs. There is a requirement to save user work as draft, and that is why I need to encrypt sensitive fields somehow.
I read a lot about Azure Key Vault and whenever I read about secrets it seems they are described to hold app settings rather then users secrets, so i am not sure if this is right to place those data.
Is Azure Key Vault secrets suitable for that job?
Moreover i am able to peek those value in azure portal as in plain text, and I want to avoid that. I suppose that I could encrypt them first and store already encrypted values, but this may be over engineering.
It's not clear what you are describing as user secrets. If it's user credentials, then you need to federate login to an Identity Provider like Azure AD or Azure AD B2C. Key Vault is NOT an identity provider, but a secret store. If it's application secrets (think connection strings) then you should look at Key Vault (with Managed Service Identity).
Conversely, Application Settings (in App Service) are exposed in the Portal but are encrypted at rest. So if you're careful about who can access what within your subscription namespace, you should be just fine.
来源：https://stackoverflow.com/questions/50061388/azure-key-vault-secret-to-store-app-users-secrets