Question

Not sure if this is even possible but I have been looking at using Regex to get an email address that is in Hex. Basically this is to build up some of my automated forensic tools but I am having problems on making a suitable Regex algorithm.

Regex for email: /^([a-z0-9_.-]+)@([\da-z.-]+).([a-z.]{2,6})$/

Hex values:

@ = 40
. = 2E
.com = 636f6d
_ = 5f
A/a = 41/61 [1]
Z/z = 5a/7a
- = 2d

This is what I have got at the moment (it only takes into account lower case and .com). But it doesn’t work! Have I messed something simple up?

"/^([61-7a]+)40([61-7a]+)23(636f6d)$/"

[1] I know email can only be lower case but I need to take uppercase into account too.

Answer 1

define classes

@ = 40
. = 2E
com = 636f6d
_ = 5f
a-z = (4[1-9a-f]|5[0-9a])
A-Z = (6[1-9a-f]|7[0-9a])
- = 2d

substitute into your regex

/^([a-z0-9_.-]+)@([\da-z.-]+).([a-z.]{2,6})$/

/^(((4[1-9a-f]|5[0-9a])|(6[1-9a-f]|7[0-9a])|[0-9]|5f|2E|2d)+)40(([0-9]|(4[1-9a-f]|5[0-9a])|(6[1-9a-f]|7[0-9a])|2E|2d)+)2E(((4[1-9a-f]|5[0-9a])|(6[1-9a-f]|7[0-9a])){2,6})$/

breaks down to…

/^
(
    (
        (4[1-9a-f]|5[0-9a])     // a-z
        |(6[1-9a-f]|7[0-9a])    // A-Z
        |[0-9]                  // 0-9
        |5f                     // _
        |2E                     // .
        |2d                     // -
    )+ // 1 or more times
) 
40
(
    (
        [0-9]                   // 0-9
        |(4[1-9a-f]|5[0-9a])    // a-z
        |(6[1-9a-f]|7[0-9a])    // A-Z
        |2E                     // .
        |2d                     // -
    )+ // 1 or more times
)
2E                              // .
(
    (
        (4[1-9a-f]|5[0-9a])     // a-z
        |(6[1-9a-f]|7[0-9a])    // A-Z
    ){2,6} // between 2 and 6 times
)$/