This check was deposited in the 1930s, and it was issued by OCBL (an old bank in Singapore). The checks issued by this bank had an interesting feature - an obfuscated pattern printed on the back of the check.

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All original documents about the design of this check have certainly been lost, and there isn't any later documentation that addresses the usage of this "pattern", but some agree that it might be an example of steganography, so that security personnel could put a cardon-grid-like card on the top of the pattern and thus reveal some information to help verify the check's authenticity.

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My question is not about deciphering the secret based on what it has to offer as steganography, but focuses on the following directions:

  1. Is this pattern really an example of steganography? Has any bank or financial institution ever printed a similar type of pattern on their checks before? If so, what is it?

  2. If it is steganography, what information could be concealed in it? As far as I know, many checks of this type share the EXACT same pattern on the back. Different patterns can be seen on other checks and bills.

  3. If it is steganography, are we able to decipher the message from the pattern? What possible methods or reverse-engineering technology could be used to detect the methods of concealment, provided that such steganography is not uniquely deployed in this case?

  • $\begingroup$ I'm not sure this suits this site. Note: stenography need not use any encryption. Also, in US, you can print your check. $\endgroup$
    – kelalaka
    Sep 24, 2019 at 15:38
  • $\begingroup$ @kelalaka while im also not sure whether this question is on topic, I don't see what archaic methods of payment used in the US have to do with this. $\endgroup$
    – Maeher
    Sep 24, 2019 at 17:06
  • $\begingroup$ @kelalaka just rephrase the question, making it suits the topic better (mainly avoid using terms related to cryptography. $\endgroup$
    – Ge Rong
    Sep 25, 2019 at 13:40
  • 1
    $\begingroup$ Stenography and steganography are quite different. Steganos- (στεγᾰνός, Greek) "covered" or "concealed". $\endgroup$
    – Patriot
    Sep 25, 2019 at 14:25
  • 2
    $\begingroup$ It doesn't need to be steganography. Hard to copy patterns are quite usual for secure printing products. I don't see too many security features on the front of the paper; this might just be a late add-on to make it harder to create copies. The fact that the same pattern is used for other checks doesn't make much sense for steganography. However, it might well be that there is some overlay to create a different, more symmetric pattern (still within a more random pattern, most likely). $\endgroup$
    – Maarten Bodewes
    Sep 26, 2019 at 1:27


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