Given some strong cipher (like TLS uses), what can be deduced from its ciphertext? For example, is the length of the ciphertext the same as original text? Are spaces preserved? Or some letter frequencies? Or the number of distinct characters?

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    Which TLS version are we talking about? There is no more padding needed in TLS 1.3. Therefore one can see the full size of the message. In general. this is not considered a security, however, depending on your risk analyze, you may need to hide it. Apart from this all cipher modes in TLS 1.3 has IND-CPA security and even more than they are Authenticated Encryption modes ( modern encryption modes unlike CBC or pure CTR).
    – kelalaka
    Mar 25, 2022 at 18:52

1 Answer 1


Length (often rounded up to the nearest block) will generally be preserved. Nothing else should be, unless you're using a very broken algorithm.

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