Copy or move the csr file to C:\
Download and install OpenSSL from http://sourceforge.net/projects/gnuwin32/files/openssl/
For example: openssl-0.9.8h-1-setup.exe
Open a command prompt and change to the following directory:
cd "C:\Program Files (x86)\GnuWin32\bin"
Run the following command:
openssl req -config "C:\Program Files (x86)\GnuWin32\share\openssl.cnf" -in c:\certrequest.csr -noout -text
If decoding an Exchange Server CSR you may the following message: unable to load X509 request
Edit the csr file to remove the blank line at the end of the request.
AbcDEFGhI1jkL2mNOPQ3RsTUVw4xY5z
AbcDEFGhI1jkL2mNOPQ3RsTUVw4xY5z
AbcDEFGhI1jkL2mNOPQ3RsTUVw4xY5z
AbcDEFGhI1jkL2mNOPQ3RsTUVw4xY5z
-----END NEW CERTIFICATE REQUEST-----