Obtain a Hash from a Excel 2007 file

Hi there, According to the Microsoft whitepaper the following specs are defined for the Excel password security encryption:

Key derivation is performed using 50,000 iterations[source] of SHA-1 (increased to 100k in SP2).
Uses a 16-byte (128-bit) random salt.
AES is the block cipher used to encrypt the document.
By default, 128-bit key are used. There is a registry tweak to change this to 256-bit.
The AES block cipher is implemented in Microsoft's CSP / CryptoAPI.

This info give me a good point to crack a Excel password, but... I don't find any information or documentation to get the hash from an Excel file.

Anyone knows how get it?

Thanks in advance and sorry for my english

Byebye!