String Hash Calculator String HMAC Calculator One-Time Password Calculator. Base64 Converter Bitcoin Address Generator. Diffie-Hellman Key Exchange. Diffie-Hellman key exchange allows two parties to generate a shared secret over an insecure channel. Diffie Hellman Calculator - fasrlosangeles. The Diffie-Hellman key exchange algorithm was first published in 1976 by Whitfield Diffie and Martin Hellman, although the algorithm had been invented a few years earlier by the British government intelligence agency GCHQ but was kept classified.
Dirty Diffie-Hellman
(Like dirty Santa, but geekier)
Crappy PHP script for a simple Diffie-Hellman key exchange calculator. I guess I could have used Javascript instead of PHP, but I had rounding errors.
Hi all, the point of this game is to meet new people, and to learn about the Diffie-Hellman key exchange. Did you ever wonder how two parties can negotiate a cryptographic key in the presence of an observer, without the observer figuring out the key? My guess is not, but bear with me. This will be a simplified version of the Diffie-Hellman key exchange (in real life, better constants and larger variables should be chosen) , in the form of a game. Enter as many times as you like.
Fixed numbers: g=10, p=541
Contestant steps:
1. Find someone you do not know, and introduce yourself.
2. One of you is Alice (a), and one is Bob (b). If genders don't match that's ok, one of you can be Alan and the other Barb for all I care.
3. Both of you choose a number between 1 and 100, but don't tell the other person this number.
4. Alice, compute A = ga mod p = 10a mod 541.
Bob, compute B = gb mod p = 10b mod 541.
Feel free to rip out your calculator or smart phone, or just use this calculator:
http://www.irongeek.com/diffie-hellman.php
5. Alice and Bob, exchange A and B verbally in the presences of Carl (Or as Chux0r points out, perhaps Christmas 'Eve').
6. Alice, compute SecretKeyA = Ba mod p = Ba mod 541. Notice the superscript is the lower case variable you chose.
Bob, compute SecretKeyB = Ab mod p = Ab mod 541. Notice the superscript is the lower case variable you chose.
7. If you did it right, SecretKeyA should be the same as SecretKeyB. Write your names, the A and B values, and the shared SecretKey outcome on a piece of paper and turn it in for the drawing.
Drawing:
The officiator will draw a piece of paper and announce the two people, the values of their A and B, and then wait 20 sec. If someone else can announce Alice and Bob's shared SecretKey in the 20 secs, they win instead.
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Take on the roles of Alice and Bob! Exchange secret keys using the Diffie-Hellman key exchange method!! Use your keys to encrypt messages!!!
The Diffie-Hellman key exchange uses a large prime p and a primitive root g of this prime. These numbers are both public.
To start the key exchange process, Alice chooses a secret number a less than the large prime, and computes ga (mod p). Alice sends this answer, call it A, to Bob. Bob now chooses his own secret number b, and computes gb (mod p). Bob sends this answer, call it B, to Alice.
Finally, Alice computes Ba (mod p), and Bob computes Ab (mod p). They both get the same answer, but no-one else will know this secret answer, because only Alice knows a, and only Bob knows b. This secret answer is their private key, which they can use to encrypt messages.
[You may wonder why someone intercepting Alice and Bob's communication can't solve gx = A (mod p) to calculate Alice's secret number a. This is a hard problem, known as the discrete logarithm problem. That this is difficult is the strength of this method of key exchange.]
First you must be Alice. Choose a large prime from the list below (or one of your own choice) and a corresponding primitive root of that large prime. Then choose a secret number which is smaller than your large prime.
Diffie Hellman Calculate
- 22953686867719691230002707821868552601124472329079 primitive root 11
- 30762542250301270692051460539586166927291732754961 primitive root 7
- 29927402397991286489627837734179186385188296382227 primitive root 2
- 95647806479275528135733781266203904794419563064407 primitive root 5
- 48705091355238882778842909230056712140813460157899 primitive root 6
- 53542885039615245271174355315623704334284773568199 primitive root 3
- 622288097498926496141095869268883999563096063592498055290461 primitive root 2
- 610692533270508750441931226384209856405876657993997547171387 primitive root 2
- 4669523849932130508876392554713407521319117239637943224980015676156491 primitive root 3
- 4906275427767802358357703730938087362176142642699093827933107888253709 primitive root 2
- 18532395500947174450709383384936679868383424444311405679463280782405796233163977 primitive root 5
- 282755483533707287054752184321121345766861480697448703443857012153264407439766013042402571 primitive root 2