Penetration Testing: Pentest Letter of Achievement/Certificate

["blowfish 448" <blowfish448 () hotmail com>]

Hi,

any of you know if any 'standards' or accepted guidelines exist for a letter 
or certification
of succesfull resistance to Penetration Testing/Vulnerability Assessment. 
Customers often
demand to have a proof delivered by their Penetration Test service provider 
to show to their
partners and customers.

The idea of course is not to disclose sensitive information but to briefly 
describe
the environment tested and how - according to which methodologies and the 
attack vectors
tested for.


Thanks in advance