Create certificate with Signature Algorithm "SHA1"

Dear experts,

When i create a private key from the Netweaver Administrator of our SAP PI 7.11 SP1 environment, this private key contains Signature Algorithm : md5WithRSAEncryption.

Our service provider, which will sign our Certificate Signing Request (PKCS#10), expects a "SHA-1 With RSA encryption".

I saw that our NW7.31 SP8 Portal system already creates a certificate with the Signature Algorithm : sha1withrsaencryption.

What will effecting the Signature Algorithm? Is this the version of the Cryptolib or the release of the Netweaver version (NW7.11 / NW7.31)? What can we do to get the "sha1withrsaencryption" Signature Algorithm in our NW7.11 system?

Thanks for your help!

Best regards,

Joost Weghorst