A month ago blog posting coproc2gatewayscript provided a preview on new GatewayScript (Javascript on DataPower) available with version 7.0.0.0 of DataPower firmware later this month.

I never worked with modules and seeing a question on how to do AES encoding/decoding in GatewayScript I thought this is a great sample for learning about modules and easily make use of libraries found on the internet.

With the first release (7.0.0.0) GatewayScript will be available there will be no crypto library support.
(This is similar to XQuery/JSONiq new with version 6.0.0.0 having no access to dp:variables and HTTP header, that came with 6.0.1.0 firmware)

A word of caution here: 
It is always better to use Encrypt/Decrypt/Sig/Verify actions instead of DataPower crypto extension functions in XSLT.
Reason is that the actions are hardened against Oracle Padding attacks -- using crypto extension functions YOU are responsible.

Anyway, since 7.0.0.0 GatewayScript does not ship any crypto funcitons, using self written or found libraries is your only current option.
 

I googled and found this nice, self-contained and interactive AES JavaScript demo:
http://www.movable-type.co.uk/scripts/aes.html

Doing "View Page Source" I saw that these 4 code parts were included into the page:
utf8.js / base64.js / aes.js / aes-ctr.js

You get them unmodified if you do "Save Page as" as "complete webpage".

{"EDIT":"11-10_2014 - files on website did change, two are missing now. Attaching June 2 version of the files here for the purpose of easily trying out aes-demo with GatewayScript. Your further (real) work should based on latest version JavaScript from above website."}
https://www.ibm.com/developerworks/community/blogs/HermannSW/resource/BLOGS_UPLOADED_IMAGES/aes-6-2-14-files.zip
 

So I decided to make 4 modules out of them, store under "local:" on DataPower and just  require("aes-ctr")  in order to use it. To make functionality available from the module the last line "module.exports = ...;" had to be appended to each file. And in order to use functionality eg. from module "utf8"    var Utf8 = require("utf8");   had to be added at the top of the modules.

Only one more change had to be done in addition to make everything work on GatewayScript, these are all diffs:

Here you can see demonstration GatewayScript  aes.demo.js  in action:

$ coproc2 aes.demo.js ../ab.json http://dp6-l3:2227

 

     Password: L0ck it up saf3

    Plaintext: pssst ... đon’t tell anyøne!

Encrypted ...: GQK5heUZjVNxqjSRRj0HzMJwPrW+OMWOaL5RXzzvfklqdViJraQ8tQ==

... Decrypted: pssst ... đon’t tell anyøne!

 

128-bit: 69 c4 e0 d8 6a 7b 04 30 d8 cd b7 80 70 b4 c5 5a 

192-bit: dd a9 7c a4 86 4c df e0 6e af 70 a0 ec 0d 71 91 

256-bit: 8e a2 b7 ca 51 67 45 bf ea fc 49 90 4b 49 60 89 

 

$ 

$ coproc2 aes.demo.js ../ab.json http://dp6-l3:2227

 

     Password: L0ck it up saf3

    Plaintext: pssst ... đon’t tell anyøne!

Encrypted ...: RQFLXOcZjVNuGspYI20khzUJKbmeb6WOFBSL/cQPfX+1pnr+pmQP+Q==

... Decrypted: pssst ... đon’t tell anyøne!

 

128-bit: 69 c4 e0 d8 6a 7b 04 30 d8 cd b7 80 70 b4 c5 5a 

192-bit: dd a9 7c a4 86 4c df e0 6e af 70 a0 ec 0d 71 91 

256-bit: 8e a2 b7 ca 51 67 45 bf ea fc 49 90 4b 49 60 89 

 

$ 

Now we have seen that  aes.demo.js  works fine, here is it completely:

The little helper function "_()" at the bottom of aes.demo.js was only intended to be a nice oneline implementation of "byte array to hex string" conversion. To my total surprise it seems to outperform other implementations by orders(!) of magnitude!?!?!

I verified that on jsperf.com, try it out yourself (I hope the test result is "real"):
http://jsperf.com/convert-byte-array-to-hex-string/7

(at least it produces the needed hexadecimal output for the NIST test vectors above)

<EDIT>
Vyacheslav Egorov pointed out that the measurements were flawed:
https://twitter.com/HermannSW/statuses/473824291109085184
</EDIT>

Hermann _{<myBlog/> <myTweets/> | <GraphvizFiddle/> | <xqib/> | <myCE/> <myFrameless/>}