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Re: Patterns

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On 2/16/2024 4:25 PM, William Unruh wrote:
> On 2024-02-16, Chris M. Thomasson <chris.m.thomasson.1@gmail.com> wrote:
>> On 2/16/2024 9:07 AM, Stefan Claas wrote:
>>> Stefan Claas wrote:
>>>
>>>> Chris M. Thomasson wrote:
>>>>
>>>>> On 2/15/2024 12:20 PM, Stefan Claas wrote:
>>>>>> Rich wrote:
>>>>>>
>>>>>>> In sci.crypt Stefan Claas <pollux@tilde.club> wrote:
>>>>>>>> Chris M. Thomasson wrote:
>>>>>>
>>>>>>>>> Or even the other way around? If one knows the OTP (Bob and/or
>>>>>>>>> Alice), they can create a special plaintext that generates this
>>>>>>>>> output for fun.
>>>>>>>>
>>>>>>>> How would you do this?
>>>>>>>
>>>>>>> For a traditional, 1940's substution style OTP, it is trivial:
>>>>>>>
>>>>>>> Message: The
>>>>>>>
>>>>>>> Pad:
>>>>>>>
>>>>>>> T=H
>>>>>>> e=r
>>>>>>> h=e
>>>>>>>
>>>>>>> Substitute using the pad, get the encrypted message: Her
>>>>>>
>>>>>> Well, one uses a substitution table, trigraph, etc. and then
>>>>>> a pad to encrypt the message. Otherwise it would be a plain
>>>>>> text encoded message, right?
>>>>>
>>>>> Give me a OPT 3 bytes long. Creating a plaintext that results in a
>>>>> ciphertext of say 123, or ABC is possible...
>>>>
>>>> Yes, but then it is not OTP encryption and only plain code, done
>>>> with substitution, I would say. The OP's Subject: is Patterns.
>>>
>>> To be more clear, an OTP encrypted message with digits or letters
>>> can of course include 3-5 letter words or a 3-5 digits sequence, but
>>> in case of OTPs this means nothing and I would not call it pattern,
>>> in an encrypted message.
>>>
>>
>> AFAICT, it all boils down to fun with OTP's... ;^)
>>
> 
> A One Time Pad means what it says. It can only be used once. It must be
> the same size as the message to be encrypted (ie you cannot use pad from
> earlier in the message to encode later stuff.) Otherwise it is weak. It
> is not a substition cypher (eg your T=H e=r h=e ) to encrypt any other
> occrances of T, h or e. That is NOT an OTP. It is a MRP (Many time pad)
> which is woefully weak. A OTP is unconditionally secret. It cannot be
> broken. An MTP is very weak, or a substitiution cypher is very weak
> unless the substition block is really large.
> OTPs are not fun. They are boring, because there is no way they can be
> broken, unless you capture the key. But of course that is their problem
> since you have to get the key to the recipient, without the enemy
> capturing the key, and the key is huge, so hard to hide.
> 

There can be some fun. Then it makes one, at least me, think about 
prepending plaintext with TRNG data and whacking it with HMAC... ;^)

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Thread

Patterns doctor@doctor.nl2k.ab.ca (The Doctor) - 2024-02-13 01:30 +0000
  Re: Patterns Jakob Bohm <jb-usenet@wisemo.invalid> - 2024-02-13 16:44 +0100
  Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-13 12:43 -0800
    Re: Patterns Rich <rich@example.invalid> - 2024-02-14 04:45 +0000
      Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-14 12:22 -0800
        Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-15 20:02 +0100
          Re: Patterns Rich <rich@example.invalid> - 2024-02-15 19:51 +0000
            Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-15 21:20 +0100
              Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-15 18:39 -0800
                Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-16 17:57 +0100
                Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-16 18:07 +0100
                Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-16 12:26 -0800
                Re: Patterns William Unruh <unruh@invalid.ca> - 2024-02-17 00:25 +0000
                Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-16 17:12 -0800
                Re: Patterns Rich <rich@example.invalid> - 2024-02-17 05:39 +0000
                Re: Patterns William Unruh <unruh@invalid.ca> - 2024-02-18 21:04 +0000
          Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-20 13:09 -0800
            Re: Patterns Richard Harnden <richard.nospam@gmail.invalid> - 2024-02-20 21:55 +0000
              Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-20 14:15 -0800
                Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-20 14:17 -0800
              Re: Patterns doctor@doctor.nl2k.ab.ca (The Doctor) - 2024-02-20 22:17 +0000
            Re: Patterns William Unruh <unruh@invalid.ca> - 2024-02-20 23:47 +0000
            Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-21 19:24 +0100
              Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-22 16:21 -0800
                Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-23 15:00 +0100
                Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-23 19:59 +0100
                Re: Patterns "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-02-23 12:23 -0800
                Re: Patterns Stefan Claas <pollux@tilde.club> - 2024-02-24 20:25 +0100

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