Bank+or+Spender

PLEASE get your public information done before Monday because The Merchant needs time to interact with Spenders and Bankers before Tuesday's class. The sooner the better! Friday: The Merchant is ready to see two coins. You can print the coins here.

I'd like a "bunny". (10751, 9983, 2 8 606, 36247, 7152, 9004) user:ian.hart Our finalized coin is (55795, 52105, 13089, 57083, 15002, 6714) user:meganternes The merchant fails to verify the coins. I'm going to re-do Ian's coin because the stricken line might mean I use Kayla's choices of P,Q, g for Ian's calculations.user:mcdaniel30 Here's Ian's coin, first check fails again. The Merchant is redoing everything.

Declaring myself to be the central authority as well as a spender, mostly because we need one for g 1 and g 2. So we're using P = 40127, Q = 20063, g = 25, g 1 = 563, g 2 = 7161. That work for everyone? user:ian.hart I already started with P=60539, Q=30269, alpha=2, and g=4. Megan and I are going that route. user:kml003 Works for me. Double set-up! user:ian.hart

Each of you has to complete your assigned work in a digital cash exercise. So you'll have to actually communicate some numbers back and forth in order to experience the layers of verification used. Follow the steps in the book and you should be fine. I hope the notes from last class help with the sequence of steps!

Ian is a Spender

Bailey is Ian's Banker

Bailey and Ian's Public: P = 40127 Q = 20063 alpha = 5 g = 25 g1 = 563 g2 = 7161 user:ian.hart

Bailey Bank ID: (h, h1, h2)=(27574, 21024, 38886) user:bea001

Megan is a Spender (muggle) Lies! I'm a Ravenclaw! Dolores Umbridge is here with some dementors. Apparently there is some question about how you obtained your wand. Didn't we decide last class that Umbridge was mopping floors at the Ministry. Anyway, since Harry, Ron, and Hermione helped to get the MoM back on track, I highly doubt there is any of that nonesence going on anymore. I also think Harry would have been very reluctant to let her stay on, even if she was just mopping floors. [|post book 7 life] Kayla is Megan's Banker but she is human, not a goblin. Good. Because even Griphook is slightly sketchy.

Your merchant is ready for business. M = 43. We're having a sale on all Penn State Dark Magic merchandise. Nice. Is that too soon? Wow, a reference thats not harry potter related! Oh, good. I've always wanted a way to buy things from Borgin and Burkes without anyone knowing it was me. Now I can with my digital wizarding cash! What should I purchase first? Malfoy already bought the Hand of Glory (unless they had more than one/got it back), but maybe the Vanishing Cabinet is still there... user:meganternes

Set up your public information here and email it to your correspondent. Kayla and Megan public: P= 60539, q=30269, alpha=2, g=4 g1=23283, g2=53089 Bank ID: h1=48776, h2=37515, h3 =12446 user:kml003

Megan's account number I = 28356 user:meganternes

Let's try keeping our secret stuff secret. I want to play the Merchant and make sure your coins pass the checks which the Merchant performs, etc. In real life, none of us would have anyone else's secret information.

Here are some numbers you might useful. Safeprimes and primitive roots from Maple:
 * prime P || prime Q || primitive root of P || suggested g ||
 * 40127 || 20063 || 5 || 25 ||
 * 50147 || 25073 || 2 || 4 ||
 * 60539 || 30269 || 2 || 4 ||

Let's use the same two hash functions I made up for class because they're dead-easy. H adds the five integers mod Q. H_0 multiplies the four integers mod Q.

Don't forget, Maple handles the -1 exponent mod Q for the size of numbers we're using. You don't even need intelligent mod. These 5 digit primes will require Maple.