So I'm trying to decrypt/decode some text strings. I don't believe they're hashes because they vary in length too much and the software they are used for is able to easily decode them and display them to the user. (I also have no access to the source code) My end goal is to be able to replace the encoded text with my own encoded text so what ends up being displayed is changed.

Some examples of the encoded text:


EDIT in response to the Hold: I'm not asking for these to be decoded for me. I'm asking how I would go about doing it. Also I'm not breaking into a system...

  • Can you give an example of a decoded string together with it's encoded counterpart? – Tokk Sep 28 '14 at 9:25
  • This has nothing to do with security. Why do you even think that the strings are encrypted? – Gilles 'SO- stop being evil' Sep 28 '14 at 11:35
  • Torin - as Gilles pointed out, this has nothing to do with Information Security as per our faq. – Rory Alsop Sep 29 '14 at 12:02
  • I'm pretty sure this falls under the category of using cryptography... – Torin Sep 29 '14 at 16:34

I suspect these are a modified base64 encoding: the trailing equals sign is strongly reminiscent of base64, but the [ character found in the first string isn't permitted in any of the standard base64 variants. If this is the case, you'll need to work out the mapping between encoded characters and values yourself, either by modifying the encoded strings and seeing what happens, or by comparing encoded strings to their plaintext counterparts.

  • Yeah I saw the similarity with base64 too but like you said it doesn't seem to be a standard variation of it. It's possible for me to get the plain text with a bit of work. I'll work on getting that and post it in the original question when I have. – Torin Sep 28 '14 at 0:19
  • I've added new examples with their plain text counterparts. – Torin Sep 30 '14 at 0:13
  • @Torin, The last two strings are base64-encoded ASCII with a randomized lookup table. You can figure out what the table is by performing a manual base64-encoding of the plaintext strings, using the encoded string to figure out what character represents each 6-bit group. The first two strings either use a different encoding method, or have a great deal of non-printing data: I don't have enough of the lookup table to figure out which is the case. – Mark Sep 30 '14 at 1:34
  • A partial lookup table: 0: 0, 5: H, 6: z, 17: C, 21: l, 22: X, 25: 3, 26: o, 27: M, 37: w, 46: 9, 48: T, 55: V – Mark Sep 30 '14 at 1:35
  • I had a little trouble figuring out what you were saying when I first read that, (Obviously I don't know an incredible amount about this kind of thing or I wouldn't be asking the question in the first place) I did a bit of research though and I think I'm starting to understand. I'll keep working on this on my own but I think this pretty much answers the question so I've marked it as the answer. Thanks for the help. – Torin Sep 30 '14 at 6:00

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