PBKDF2 encryption

Do you know the PBKDF2 encryption?
It's the encryption used on Wi-Fi, Mac and more systems. You may read something here: http://en.wikipedia.org/wiki/PBKDF2


refaktor wrote a script to use PBKDF2 encryption, and so you can use it with Rebol!

The source code is here: https://github.com/refaktor/Rebol2-PBKDF2/blob/master/pbkdf2.r

REBOL []
pbkdf2: context [
unsigned-to-binary: func [n [number!] /rev][
  if n > (2 ** 31 - 1) [n: n - (2 ** 32)]
  n: load join "#{" [form to-hex to-integer n "}"]
  either rev [head reverse n][n]
]
calc-sha1: func [pwd salt count key-len /string
  /local hash-len block-len output i j ] [
  hash-len: length? to-string checksum/secure ""
  block-cnt: round/ceiling (key-len / hash-len)
  output: copy #{}
  repeat i block-cnt [
  last: join salt unsigned-to-binary i
  last: xorsum: checksum/key last pwd
  repeat j (count - 1) [
    xorsum: (xorsum xor (last: checksum/key last pwd))
  ]
  output: join output xorsum
  ]
  output: copy/part output key-len
  either string [trim/with enbase/base output 16 #"^/" ] [output ]
]
]


MD5 checksum

If you use Rebol 2, don't use the checksum/method 'md5 since is broken.
Fortunately Andreas Bolka made a script to correct this behavior:

md5sum: func [
    "Returns an MD5 checksum for the contents of the file given."
    fname [file!] /local fport sport chunk-size
] [
    chunk-size: 4096 ;; 4K chunks, just like in md5sum (matches page size)
    fport: open/seek/binary/read fname
    sport: open [scheme: 'checksum algorithm: 'md5]
    while [not tail? fport] [
        insert sport copy/part fport chunk-size
        fport: skip fport chunk-size
    ]
    close fport
    update sport
    sum: copy sport
    close sport
    sum
]


The Rebol 3 checksum works well, unfortunately is not so friendly as the Rebol 2 version: the R3 wants a binary as input, so you have to write:
checksum/method (to-binary read %myfile)   'md5


Compression

You know that Rebol compress function compress data, but you can manipulate also TAR.GZ archives and ZIP archives.
For TAR.GZ archives there are the following script:

• http://www.rebol.org/download-a-script.r?script-name=gunzip.r
• http://www.rebol.org/download-a-script.r?script-name=gzip.r
• http://www.rebol.org/download-a-script.r?script-name=gunzip.r
• 
  

They can be used this way:
do %tar.r
do %gzip.r
write/binary %test.tgz gzip tar [%some-files ...]


Resulting archive is usually smaller than a *.zip of the same files
To decompress use  gunzip.r script

For ZIP archives there is the following script: http://www.rebol.org/download-a-script.r?script-name=rebzip.r
usage: zip/deep %new-zip.zip [ %readme.txt "An example" ftp://192.168.1.10/my-file.txt %my-directory/ ]
to unzip unzip %new-zip.zip

If you want to only explore a zip file without decompress it, you can use this script: http://www.rebol.org/download-a-script.r?script-name=zip.r