[mapserver-users] msencrypt - tea algorithmos

[Daniel Morissette]

On 12-01-03 1:07 PM, Andreas Douvalis wrote:
> In my MS_ENCRYPTION_KEY I have the 32 chars key created by msencrypt.exe
> (ms4w-mapserver 6).
> TEA algorithm needs one 16-chars password to encrypt the string. How
> msencrypt works? How produce the 16-chars password from 32-chars key?


As Jeff already wrote, you will find some information in RFC-18 and in 
ticket #1792. You could also look at the source file mapcrypto.c for the 
implementation details of each function.

With respect to the encryption key, MapServer also uses a 16 bytes (128 
bit) key, but since the key is not limited to ASCII chars, we hex-encode 
the 16 bytes, and this results in a 32 chars value. i.e. each pair of 
two chars in MS_ENCRYPTION_KEY represent the hexadecimal value of the 
corresponding byte of the 16 bytes key. Makes sense?

> Has anybody implemented successfully php code (or other language) for
> the production of the encoded string that msencrypt tool creates?
> I found in this page (http://www.movable-type.co.uk/scripts/tea.html)
> one javascript implementation of xtea encryption but firstly it takes
> 16-chars password and secondly is xtea.
> Can I use MCRYPT_XTEA module of php to produce the encoded string that
> msencrypt tool creates?

That would be worth a try. If it's the same algorithm then it should 
produce the same result.

Note that the original (source) strings are padded with 0-bytes before 
being encrypted to align with the 8 byte encryption chunks used by the 
algorithm.

Also note that the encrypted strings that we place in the mapfile inside 
{...} are the hex-encoded result of the encryption to prevent problems 
with non-printable bytes/chars.

-- 
Daniel Morissette
http://www.mapgears.com/
Provider of Professional MapServer Support since 2000