Login to your authorize.net account. HOW TO CREATE AUTHORIZE.NET API LOGIN & API TRANS KEY
Then from left menu click on "Settings" link. See screenshot
Then click on "API Credentials & Keys". See screenshot
Then follow the steps -
Step 1: Choose either New Transaction Key or New Signature Key.
Step 2: If a previous key exists, choose whether to disable it. If you do not choose to disable the old key, it will expire in 24 hours from the generation of the new key.
Step 3:Verify your identity by requesting and supplying a PIN.
After verifying your identity, the key is shown.
If you still want to contact us please login
to your account and from top click "Contact Us".