Is there a utility that is available in standard windows 7 installations, that allows me to convert DER-encoded certificates to PEM-encoded certificates or shows me the ASN.1 text of a DER-encoded certificate?
Not exactly an "utility", but you can import PEM certificates into Windows Certificate Store and export them back as DER.
In fact, Windows supports PEM-encoded certificates just fine, it just doesn't recognize the
"PEM encoded" means nothing more than Base64-encoded DER, between "begin"/"end" headers. You can use any Base64 decoder for this.
For example, PowerShell has
You can also use OpenSSL for Windows:
openssl x509 -in foo.pem -out foo.der -outform der
openssl asn1parse -in foo.pem openssl asn1parse -in foo.der -inform der
or this online ASN.1 decoder.