how to encrypt password before writing to txt file and decrypt when needed to use it [duplicate]

This question already has answers here: Encrypt and decrypt a string in C#? [closed] (29 answers) 开发者_如何学运维 Closed 3 years ago.

i am storing the connection string provided by the user at setup time to a txt file

its a website

by setup i mean first access of the admin to the site

well

its working

but i need some code which can encrypt the password text and store to file so any one having access to the system can not understand the passward,

also please show decrpytion

thank u

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Anyone who has access to your system is able to read the connection string as long as the program is able to decrypt it without having the user enter a password.