Re: OTP (One-Time Pad Generator Program) and MD5 signature

From: Harald Hanche-Olsen (hanche_at_math.ntnu.no)
Date: 04/18/05

  • Next message: Anne & Lynn Wheeler: "Re: OTP (One-Time Pad Generator Program) and MD5 signature" 
    Date: 18 Apr 2005 18:03:01 +0200

    + "Alex Vinokur" <alexvn@x-privat.org>:

    | "Harald Hanche-Olsen" <hanche@math.ntnu.no> wrote in message news:pcozmvx3vip.fsf@shuttle.math.ntnu.no...
    | > The idea is this: The program creates a sequence of
    | > passwords together with their MD5 hashes.
    |
    | For instance,
    | 1) Current session key and its MD5 signature: gtweuzpy 04AE0013DFAC7807A4846425AAE03D48
    | 2) Next session key and its MD5 signature: choginzx 5C35E01460B99DCFD633C452DDA3D88F
    |
    | > You keep the password, the
    | > computer keeps the hashes. Now, when you wish to log in, or use some
    | > password protected service on the computer, you pick the next password
    | > from the list and send it (in the clear) to the computer, which
    | > compares it with the next hash on its list.
    |
    | The recipient picks key 'choginzx'.
    |
    | > If they match, you're in.
    |
    | The computer searchs 'choginzx' in the list and checks its MD5 signature.
    | Is MD5 signature used here?

    Almost: You send 'choginzx', the server computes the MD5 signature,
    and checks it against the next MD5 signature in its file. If they
    match, it lets you in. It also marks that signature as having been
    used, so it cannot be used again to gain access.

    (I'm confused by your use of the word recipient, though: This is for
    access control, not for sending and receiving encrypted messages.) 

    -- 
* Harald Hanche-Olsen     <URL:http://www.math.ntnu.no/~hanche/>
- Debating gives most of us much more psychological satisfaction
  than thinking does: but it deprives us of whatever chance there is
  of getting closer to the truth.  -- C.P. Snow
  • Next message: Anne & Lynn Wheeler: "Re: OTP (One-Time Pad Generator Program) and MD5 signature"

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