My question has been put on hold and I would like to understand exactly why and how I can make it better.

I have a software engineering background but cryptography is way out of my league, so I definitely need help from experts to identify what cryptography techniques are at play in my question.

I've explicitly mentioned that I wasn't looking for anyone to do my "homework". I would like to do this on my own but would definitely appreciate any tips to get me started in the right direction.

I feel my question didn't deserve this but I'm happy to be proven wrong.

  • $\begingroup$ What part is not clear to you w.r.t the reason? This is ciphertext analysis, without additional hints. That it is put on a pretty postcard doesn't make it any different for us. $\endgroup$
    – Maarten Bodewes Mod
    Apr 29 '19 at 8:57
  • $\begingroup$ Thank you for your comment. As I'm new to cryptography what may seems obvious to you isn't to me. If I can extract the text would that help? $\endgroup$ Apr 29 '19 at 9:00
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    $\begingroup$ @customcommander Unfortunately we don't even know if it is a cipher at this point. Even if it is though, simply having the ciphertext isn't usually enough for us to do anything. If you want to know how to properly use frequency analysis to break it, you could ask that (assuming it isn't a duplicate of another question), but we aren't going to be able to simply "decode" it. Cryptography doesn't work like that. $\endgroup$
    – forest
    Apr 29 '19 at 9:00
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    $\begingroup$ No, we close it mainly because it is just ciphertext. It will still be ciphertext on whatever medium you put it on. Note that SE is trying to build a knowledge base. However, your question is basically only of help to you. We'd have to start all over again for the next ciphertext, without even knowing that there is an answer. $\endgroup$
    – Maarten Bodewes Mod
    Apr 29 '19 at 9:02
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    $\begingroup$ I recommend you look into frequency analysis and substitution ciphers. Transliterate the symbols and run a frequency analysis on them. The letter with the highest frequency of use is likely to be the letter e, for example. There are lots of sites that explain how to do this. We can't do that for you. $\endgroup$
    – forest
    Apr 29 '19 at 9:04
  • $\begingroup$ @forest Thank you. This is the kind of answers I was looking for. Maarten Bodewes maybe my question wasn't formulated in the most appropriate way but I feel that closing it down prevents forest from sharing this useful answer to a wider audience (it's useful to me at least). $\endgroup$ Apr 29 '19 at 9:08
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    $\begingroup$ @customcommander I think a search of this site may show the same techniques that I've described. But note that, in the very possible situation that frequency analysis doesn't work, it might be simply too difficult to decode this cipher without a lot more ciphertext. We usually deal with ciphers where even the most broken ones requires gigabytes of data to even begin to be breakable, so a single cipher with a couple of lines of symbols isn't much for us (or anyone) to go on. My advice is a shot in the dark. $\endgroup$
    – forest
    Apr 29 '19 at 9:09
  • $\begingroup$ Ok thank you all. This was useful. $\endgroup$ Apr 29 '19 at 9:28
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    $\begingroup$ Actually perhaps the puzzle stackexchange might be a good place to post it? For all intents and purposes this looks like a riddle therefore wouldn't be out of place there. $\endgroup$
    – S. L.
    Apr 30 '19 at 12:27

Unfortunately, those kinds of questions are off-topic. See this Meta question. The issue is that we get way too many of those questions, and they are usually of low quality or only tangentially related to the subject of cryptography (we got a question once where someone posted an image of a Pokemon called Unown, which looks like a letter, and asked what cipher it is!). Not to mention, most of the times what is posted cannot be either decoded or identified without further information. What I see from your postcard looks like a mess of Greek letters. It could be a simple substitution cipher, but unless it's really trivial (e.g. a monoalphabetic substitution cipher), we'd need a lot more sample text to be able to decode it.

Although there is some overlap, this is the kind of thing we deal with:

Twofish cipher diagram

Not this:

Zodiac killer cipher

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    $\begingroup$ IMO, in principle, a general question asking how to analyze a classical cipher using nonstandard ciphertext symbols could be on-topic here. That said, it might also end up being a duplicate of e.g. this early question. $\endgroup$ May 1 '19 at 19:15
  • $\begingroup$ @IlmariKaronen Exactly why I mentioned that there is some overlap between the two. $\endgroup$
    – forest
    May 4 '19 at 1:32

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