Keyhash for android facebook login in MAC

1. First open a terminal (open a command prompt in windows).
2. Navigate in the terminal to the directory where your Android debug.keystore is stored.
3. Mostly it will located under “/Users/user_name/.android/” (In Windows will be C:\Documents and Settings\.android).
4. Once you are in the “.android” directory, run the following command.
   keytool -exportcert -alias androiddebugkey -keystore debug.keystore | openssl sha1 -binary | openssl base64
5. When it prompts you for a password, type android and hit Enter
6. Copy the value printed in the terminal that ends with an “=” and paste it in the Key Hash field in Facebook. Then click the Save Changes button.

Reference: Integrate Facebook logins in your Android app