Semantic Security and the One-Time Pad

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  • čas přidán 7. 09. 2024

Komentáře • 8

  • @CORAcsi
    @CORAcsi Před rokem

    Interesting video, though it constantly surprises me that no one has openly imagined the MUP (Multiple Use Pads) that I have designed. Yes, it is possible to create an OTP that is reusable. Sure, it should be called a modified Vigenère cipher, or Vigenère 2.0, however, I like MUP better. If you are curious, take a look; verifying that MUPs are indeed reusable isn't difficult; you can use one of these MUPs on innumerable messages and try to break it.

  • @maomxesoax2471
    @maomxesoax2471 Před 3 lety

    OTP,++. Beyond the pad and key.
    1) A randomised character set (RCS). Character Set Length (CSL)
    2) A number that gets split into pairs of digits ie: '334688......' is 33 46 88......
    3) Any text as the pad.
    Encryption formula is ((M+O)-X) mod CSL. M = message char. O = pad char. X = number
    Decryption formula is ((E-O)+X) mod CSL. E = encrypted char
    Using those numbers...
    For the first encryption the CS is rotated. Odd left, Even right by X. So 33 left. Then the characters 33 46 and 88 are removed from the CS and placed at the beginning of it. The message is encrypted with the new CS and the cipher text produced is used for the second encryption. The CS is rotated right 46 and the characters 33 46 and 88 are removed and placed at the start of the new CS. The process is repeated for 88.
    The final encryption being the cipher text to send. Decryption, just reverse the above operations.
    The sender and receiver share the RCS and number. The any text is text from a book, magazine, paper etc.
    An example: A Random Character Set: The CSL is 94.
    Cdpe o+^3I]AP-?E}#"xq!Y(UNF[Q{uJ8$5Zkm_,aSLyTB%c=OjgG*2w7Ms6')KhH:~R.fzr
    A number, to keep it simple: '02030405'
    Some text for the pad. In this case, using your paragraph above: message length= 65. Multiply it by the number '02030405' length divided by 2 equals 4. The text is 65 x 4 = 260 characters long.
    Confidentiality, authenticity, integrity, ciphers, plaintext, ciphertext, encryption, decryption, keys, key generation function, uniform random, semantic security, bits of security, brute force, Kerckhoff's principle, semantic security, ciphertext indistinguis
    Encrypted message:
    f

  • @aaronli1240
    @aaronli1240 Před 4 lety +1

    Great video - why do you say IND-EAV is too "strong" (as oppose to too weak because you can assume attackers can do more)? Would be correct to understand IND-CPA to be stronger than IND-EAV? Thanks

    • @thegamingruler1996
      @thegamingruler1996 Před 4 lety +2

      I think he means that it's too strong of an assumption that the attackers can ONLY do IND_EAV. Like modern hackers can send queries and stuff to the encryption system, and get back data. They aren't only limited to eavesdropping.

    • @aaronli1240
      @aaronli1240 Před 4 lety

      THEGAMINGRULER gotcha thanks. That makes sense

    • @aleksanderessex7328
      @aleksanderessex7328  Před 4 lety +4

      @@aaronli1240 yes, the terms "stronger" and "weaker" are a constant and non-intuitive source of confusion in the crypto world. I probably should have more clear but as was pointed out, I'm applying the term "strength" to the assumptions that we're making about the adversary, i.e., that they can ONLY eavesdrop. But yes, you're right, IND-CCA2 is a stronger notion (in the intuitive sense of the word).

  • @user-ex5cg9gn5m
    @user-ex5cg9gn5m Před rokem

    on 1:22, according to WikiPedia, The key must be at least as long as the plaintext, not just exactly the same length as plaintext, en.wikipedia.org/wiki/One-time_pad#:~:text=The%20key%20must%20be%20at,according%20to%20Gregory%20Chaitin%20definition.

    • @aleksanderessex7328
      @aleksanderessex7328  Před rokem +2

      The important point here is that the encryption function consumes one bit of key material for one bit of plaintext. Could you generate a duodecillion random bits and then encrypt just one bit? Absolutely. But you still only consume one bit of key material. The rest is unused. What happens to this leftover? Now we get into the opsec headaches of the OTP...