Sign XML-File with OpenSSL (Output: detached XMLDsig-Signature)

it's me - the openssl noob - again. ;)

This time I would like to know how to sign a xml-file and generate the signature file in xmldsig-format.

Example This is the file I want to sign: - abcd.xml

These are the key- and certificate-files I have so far: - key.pem - certificate.pfx - certificate.pem

This is the output-file I would like to have in xmldsig-format: - abcd.sig

I think for someone who is more experienced in openssl this job is no magic and I really need some help!

Thanks in advance!