Let's say I use RSA encryption, it's 2048 bits and I use a simple character padding scheme, every character is turned into a 3 digit number and strung together, then encrypted. Saying that no message will be below 40 characters, ending up in a 120 digit number, how insecure is this?

Edit: The public exponent is as small as it could be, let's say 7 in this case

  • $\begingroup$ with what public exponent? ​ ​ ​ $\endgroup$ – user991 Dec 29 '15 at 7:35
  • $\begingroup$ The public exponent is 7 or more $\endgroup$ – AppIns Dec 29 '15 at 8:11
  • $\begingroup$ I could pretty easily identify $40 \times 3$ digits set to zero, so it's not secure by that observation alone. Repeating the plaintext would also be an issue. $\endgroup$ – Maarten Bodewes Dec 29 '15 at 15:03
  • $\begingroup$ What do you mean 40 * 3 digits "Set to zero?" And I don't understand repeating the plaintext, I'm 14 by the way. $\endgroup$ – AppIns Dec 29 '15 at 21:37

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