Solve Cryptography Exercises: Rabbin & RSA Protocols

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Discussion Overview

The discussion revolves around two cryptography exercises involving the Rabbin protocol and RSA signatures. Participants seek assistance in solving these problems, which involve encryption and signature generation within the context of cryptographic protocols.

Discussion Character

  • Homework-related

Main Points Raised

  • One participant presents a problem involving the Rabbin protocol, specifying parameters p=31, q=51, B=15, and a message M=20, asking for the encrypted message C and the decrypted messages.
  • The same participant poses a second problem related to RSA, where Alice's public key is given as (n,e)=(667,3), and seeks to determine the signature for a message m2=46 based on the signature of another message m1=26, without using factoring or finding the private key d.
  • Another participant inquires whether the problems were assigned as homework, indicating curiosity about the context of the exercises.
  • Further exchanges reveal that the original poster is studying from a book titled "Introduction to Cryptography" by Johannes Buchmann.

Areas of Agreement / Disagreement

The discussion does not reach a consensus, as participants are primarily focused on seeking help with the exercises rather than debating or agreeing on solutions.

Contextual Notes

Participants have not provided specific assumptions or constraints related to the exercises, and there is no indication of the mathematical steps required to solve the problems.

Who May Find This Useful

Readers interested in cryptography, particularly those studying protocols like Rabbin and RSA, may find the discussion relevant.

kopros
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Hi I have stuck at these two exercises ...



1)

Suppose we use the Rabbin protocol and we have chosen p=31,q=51 and B=15. If we want to transmit the message M=20 which will be the encrypted message C?? Also what are the messages the recipient will receive decrypting C ??



2)

Suppose we work in RSA and Alice has the public key (n,e)=(667,3). Suppose m1=26, m2=46, and the signature of Alice in m1 is sig(m1). We want to find sig(m2). We have the right to give her a message x, x different from m2 and she will sign it. We can't use the factoring of 667 neither can we find the d from e=3. What message should we give her?

thnx a lot
 
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kpros,

was this assigned as a homework problem in a class?

just curious.

DJ
 
Hi,
no I am just trying to solve them from a book I study these days..
 
kopros said:
Hi,
no I am just trying to solve them from a book I study these days..

Kopros,

What's the name of the book?

DJ
 
Introduction to Cryptography by Johannes Buchmann
 
I'll see if I have a copy. DJ
 

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