AES means Advanced Encryption Standard.
PDF encrypted with AES method, will open supports Adobe Reader 6.0(or Acrobat 6.0) and upper, but also more safer.
and there are also a bad news, pdfcrack supports crack PDF with AES encryption. and there exists win32 version.

Here I collect some useful applications have source code that can help you easily convert Tiff or Fax to PDF, some support windows, some support linux, some support both.

Convert Tiff To Pdf:Tiff To PDF conversion Source Code.
Scan2PDF:A utility for bulk scanning, converting the scanned pages to PDF and burning them on CD/DVD for archiving.
Fax G3 [...]

Update:

If you have know the password, and want to remove the password, please use this free software,PdfCrypt
PDFCrack 0.11 for Window Releases

Some body compiled a windows version pdfcrack by using Cygwin, it needs cygwin1.dll, but he does not offer, I download it and add cygwin1.dll, so you can directly use it after download.
I have test it, [...]