Brute force AES-256 knowing 90% of pass?

[rsberzerker]

I think Centurio has pretty much given you the correct info. If you know something about the 5 digits, you could narrow things down further. For example, 5 digits could be a date. Do you have any idea what format you would have used. It could be

• a 2 digit month, 1 digit day, and 2 digit year. In which case, the first digit is either a 0 or 1 (assuming you pad your single digit months with a 0). That eliminates a good number of candidates. Use a custom mask, something like 01,?1?d?d?d?dword1word2 . If you don't pad, then it's simpler: 1?d?d?d?dword1word2
  
• a 1 digit month, 2 digit day, and a 2 digit year. In this case, the first day digit can only be 0, 1, 2, or 3 (and maybe not a zero if you don't pad your days). The mask would be 0123,?d?1?d?d?dword1word2 with padding. With no padding, it is 123,?d?1?d?d?dword1word2
  
• a 1 digit month, 4 digit year. In which case the first year digit is likely a 1 or 2, so the mask would be 12,?d?1?d?d?dword1word2