How to verify accounts (logins)?

[spode]

I have two field. in the first one the user writes his own data (user or password) and in the second one he writes his password. How verify these login data?

[tobias.hunger]

That depends on how you want to authenticate the user. Is this a application specific login dialog, some database, the OS, a service on the network, etc.?

[ninio]

Well, there is some ways to do it. You can check the fields against a data base.

[absfrm]

if you have any database or data files , you can authenticate the user very easy.
For Example :
use can use sqlite db with hash password.

[DerManu]

[quote author="abbas farahmand" date="1342495126"]
use can use sqlite db with hash password.[/quote]

With salted hashed password.
http://en.wikipedia.org/wiki/Cryptographic_salt

Further, don't use a fast hash function like MD5 or SHA. Use a scheme that you can make slower as computing power grows, without breaking your code. See for example
http://en.wikipedia.org/wiki/Bcrypt

If the authentication happens over the network, use a nonce (and SSL).
http://en.wikipedia.org/wiki/Cryptographic_nonce

If you think this is too much work, don't write the program. Don't implement your security/authentication layer as dilettantish as sony, last.fm, eHarmony, linkedin etc. did – You've read in the news what happens.