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8 Cards in this Set
- Front
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ciphertext-only attack (COA) or known ciphertext attack (KCA) |
The attacker only has ciphertext and information about the ciphertext like the attacker might know the language in which the plaintext is written in or the expected statistical distribution of characters in the plaintext. |
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known-plaintext attacks(KPA) |
An attack where the attacker has access to both the plaintext and its encrypted version (ciphertext). These can be used to reveal further secret information such as secret keys and code books. |
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chosen-plaintext attack |
In chosen plaintext attack you get to choose the plaintext which can be useful. In this case the attacker determines what will be encrypted and then uses the result to determine the key (or perhaps other less useful information) of the encryption. |
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posterior probability |
The conditional probability that is assigned after the relevant evidence or background is taken into account. "Posterior", in this context, means after taking into account the relevant evidence related to the particular case being examined. |
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Perfect Secrecy |
Pr[C =c|M =m]=Pr[C =c] i.e., prior and posterior probability are the same |
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Perfect indistinguishability |
Let C(m) denote the distribution over the ciphertext when the message being encrypted is m ∈ M. Then for every m0,m1 ∈ M, the distributions C(m0) and C(m1) are identical. This is just another way of saying that the ciphertext contains no information about the plaintext. We refer to this formulation as perfect indistinguishability because it implies that it is impossible to distinguish an encryption of m0 from an encryption of m1 (due to the fact that the distribution over the ciphertext is the same in each case). |
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Probability Distribution |
A probability distribution is a table or an equation that links each outcome of a statistical experiment with its probability of occurrence. |
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One-Time Pad |
Gen: choosing a string from K = {0, 1}l according to the uniform distribution Enc: c := k ⊕ m Dec: m := k ⊕ c |
