What is a ciphertext only attack and how OTP is unbreakable using this attack

Chinmay Pant

11/15/22, 6:23 PM

I was wondering that what actually is cipherText-only attack and how the One Time Pad Encryption cant be broken by this attack?

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encryption

one-time-pad

classical-cipher

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Crypto

Hormoz

11/15/22, 9:53 PM

A Ciphertext-only attack is what it sounds like, it's a type of attack model in which the attacker only knows the ciphertext (encrypted text) and has no knowledge of the plaintext (decrypted text). In practice though, usually the attacker has at least some knowledge of the plaintext, like the set of characters used or the language used.

A one time pad can't be broken because there are many answers (that make sense) given a ciphertext, so there is no way to know the actual intended plaintext. Generally encryption methods yield nonsense if decryption fails for most part, so it's possible to try out all possible keys until you reach an answer, but with something like OTP, this is not possible.

As a simple example if I give you "xxxx" as a ciphertext and tell you to break it, the answer could be "what" or "when" or "past" or any other 4 character thing depending on the key, you have no way to know which one it is.

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Chinmay Pant

11/16/22, 3:50 PM

All right, its almost clear. Just to confirm, in OTP, if we only have cyphertext _c_ and nothing else, so there is no way to predict about the plaintext or the key. Is it right? Thanks

Hormoz

11/16/22, 6:21 PM

As I said, if you only have the cipher text of a perfect OTP, then, there is no way to know what was the intended plaintext. So there is no way.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: What is a ciphertext only attack and how OTP is unbreakable using this attack

TH: การโจมตีแบบไซเฟอร์เท็กซ์เท่านั้นคืออะไร และ OTP ไม่สามารถแตกได้อย่างไรโดยใช้การโจมตีนี้

RO: Ce este un atac numai cu text cifrat și cum OTP este de nedisrupt folosind acest atac

RU: Что такое атака только с зашифрованным текстом и как с помощью этой атаки невозможно взломать OTP

VI: Tấn công chỉ bằng bản mã là gì và làm thế nào để không thể phá vỡ OTP khi sử dụng cuộc tấn công này

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