If you’re developing apps for iOS (iPhone, iPod touch or iPad) you’ll need to generate a 2048-bit Code Signing Request (CSR) before you can create a Development Certificate and start testing your apps.

On OS X, you can use Keychain Access, but on non-server editions of Windows it’s a little less straight forward. Here’s how:

1. Download and install the latest version of OpenSSL
2. Once installed, you will need to add the OpenSSL bin folder to your PATH environment variable, e.g. c:\openssl\bin; if you’re not sure how, Google has the answer
3. Open a command line window by selecting Start > Run… and entering “cmd”, then pressing OK
4. To make sure you can find your CSR once it’s been created, type the following and press return:

   cd desktop

5. To create your CSR, type the following an press return:

   openssl req -nodes -newkey rsa:2048 -keyout request.key -out request.csr

6. Answer each of the questions
7. That’s it: your CSR should be waiting for you on your Desktop, ready for upload to the iOS Provisioning Portal

Once your CSR has been approved and you have your Developer Certificate, you’ll need to convert it to a P12 file: instructions are here