# Questions tagged [perfect-secrecy]

Confidentiality in a very strong sense. Ciphers reaching perfect-secrecy can't be broken to disclose informations over the plaintext from the ciphertext, even with unlimited computing power. The most known example cipher reaching perfect screcy is the one-time-pad.

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### difference between unconditionally sure, perfect confidentiality, and semantically sure, adversary-wise and advatnage-wise?

can anyone please tell me the difference between unconditionally secure, perfect confidentiality and semantically secure? I know that for perfect confidentiality, we have an adversary A that has an ...
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### Formal proof that the following definitions of perfect secrecy are equivalent

I've seen the following two definitions of perfect secrecy for an encryption scheme (Gen, Enc, Dec). ...
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### Perfectly secure cryptosystem as many keys as plaintexts

Is a cryptosystem perfectly secure if there are at least as many keys as there are plaintexts? My guess is yes but I am not sure, new to cyptosystems
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### Interpretation of message space distribution in the definition of perfect secrecy of encryption schemes

I am a beginner to cryptography, and have started reading Katz and Lindell's book titled "Introduction to Modern Cryptography". I'm unable to understand what the probability distribution over the ...
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### Perfect Secrecy and Message distributions

It is know that for a perfect secrecy scheme, for all m1,m2 and c: $Pr[C=c | M=m1] = Pr[C=c | M=m2]$ I also know that for all distributions of M, m1,m2 and c: $Pr[M=m1 | C=c] = Pr[M=m2 | C=c]$ Does ...
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Why does AES file encryption not ensure perfect secrecy? I understand that $\Pr[E(K,M_1)=C_1] = \Pr[E(K,M_2)=C_2]$ given $M1\neq M2$ holds for perfect secrecy of a scheme. However, this seems to hold ...