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exercism fetch fsharp diffie-hellman

Diffie Hellman

Diffie-Hellman key exchange.

Alice and Bob use Diffie-Hellman key exchange to share secrets. They start with prime numbers, pick private keys, generate and share public keys, and then generate a shared secret key.

Step 0

The test program supplies prime numbers p and g.

Step 1

Alice picks a private key, a, greater than 1 and less than p. Bob does the same to pick a private key b.

Step 2

Alice calculates a public key A.

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A = g**a mod p

Using the same p and g, Bob similarly calculates a public key B from his private key b.

Step 3

Alice and Bob exchange public keys. Alice calculates secret key s.

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s = B**a mod p

Bob calculates

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s = A**b mod p

The calculations produce the same result! Alice and Bob now share secret s.

Hints

For this exercise the following F# feature comes in handy:

Source

Wikipedia, 1024 bit key from www.cryptopp.com/wiki. http://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.