A .keystore file is needed when creating Android Apps. In order to create one (if you are not using Eclipse) do the following: One would do this for software like Adobe PhoneGap and its very easy to do on both the Mac and PC. Here are the steps:
1. Open up terminal (unix/dos dialog box). On the Mac this is under applications->utilities->terminal on the PC its under Start->Programs->Accessories. It will simply be a command prompt for you to type.
2. Type the following (you cannot copy/paste):
keytool –genkey –v –keystore my-release-key.keystore –alias alias_name –keyalg RSA –keysize 2048 –validity 10000
a. You need to change my-release-key.keystore to your own file name. So it could by like: raypastore.keystore if I wanted. This will be your file name.
b. alias_name should be changed to another name as well. PLEASE REMEMBER THIS. You will more than likely need this to use your .keystore file.
3. Press enter. You will be prompted with a few questions asking your name and such. Please remember your password.
4. Use the file. You will need your alias name and password. If you have trouble finding the created file just do a file search for .keystore and it will come up.