# Introduction to Cryptography

Consider the extension of the One-time Pad cipher, where a ciphertext c is possibly longer than the plaintext m (and the key k) by one bit, namely, by having algorithm Enc append to m⊕k a 0 or 1, with probability 0:65 or 0:3, respectively. Is this extension a perfectly secret cipher and why?

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• Welcome to Cryptography.SE. As written it stands as a HW dump. As per our HW policy, you should show us what you tried and where you failed to advance. Did you read the perfect secrecy? And, note that the probabilities don't add to $1$!. – kelalaka Apr 7 at 16:59