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authorMarkus Teich <markus.teich@stusta.mhn.de>2016-06-08 15:40:22 +0200
committerMarkus Teich <markus.teich@stusta.mhn.de>2016-06-08 15:40:22 +0200
commitd4360a4f8b7d29aedf6f9af0a878a9060d434ea2 (patch)
tree40836708043afa8fb7c1a320e86e652fec44dd14 /gp-scripts
parent8cf93a6c188d6a726bce46aa987c11611cf2baac (diff)
fix typos and types
Diffstat (limited to 'gp-scripts')
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1 files changed, 91 insertions, 0 deletions
diff --git a/gp-scripts/m+1stPrice b/gp-scripts/m+1stPrice
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+\\ From: "Fully private auctions in a constant number of rounds" (2003) by Felix Brandt pages 9-10
+
+
+\\\\\\\\\\\\
+\\ Adapt the following values to your needs
+\\\\\\\\\\\\
+
+\\ amount of bidders
+n = 2^3
+\\ amount of possible prices
+k = 2^7
+\\ randomize bids (change to something static, if you like)
+bid = vector(n,i,random(k)+1)
+\\bid = vector(n,i,n-i+1) \\ first bidder wins
+\\bid = vector(n,i,i) \\ last bidder wins
+\\bid = vector(n,i,(i+1)%2) \\ second bidder wins (with ties)
+
+\\ prime finite field setup (result may be ambiguous if your prime is too small, 4*n*k seems to work fine)
+q = prime(4*n*k)
+
+\\\\\\\\\\\\
+\\ SETUP
+\\\\\\\\\\\\
+
+\\ p not needed? wat?
+\\p = 47
+
+\\ get generator / primitive element for Z_q
+var = 'x \\ copy pasta from internet
+pe=ffgen(minpoly(ffprimroot(ffgen(ffinit(q,1))),var),var) \\ get primitive element
+1/(fforder(pe) == q-1) \\ error out, if ord(pe) is wrong
+g = Mod(eval(Str(pe)), q) \\ dirty hack to convert t_FFELEM to t_INT
+
+\\\\\\\\\\\\
+\\ PROLOG
+\\\\\\\\\\\\
+
+\\ private keys of agents
+x = vector(n,i,random(q))
+\\ public keyshares of agents
+yshares = vector(n,i,g^x[i])
+\\ shared public key
+y = prod(X=1,n,yshares[X])
+
+\\ first index level = owning agent id (additive share)
+\\ second index level = agent id, price id
+m = vector(n,i,matrix(n,k,a,b,random(q)))
+
+\\ index = owning agent id, price id
+r = matrix(n,k,i,j,random(q))
+\\ bid matrix
+b = matrix(n,k,i,j,g^(bid[i]==j))
+
+\\\\\\\\\\\\
+\\ ROUND1
+\\\\\\\\\\\\
+
+\\ encrypted bids
+alpha = matrix(n,k,i,j, b[i,j]*y^r[i,j])
+beta = matrix(n,k,i,j, g^r[i,j])
+
+\\\\\\\\\\\\
+\\ ROUND2
+\\\\\\\\\\\\
+
+\\ multiplicative shares
+\\ first index level = owning agent id (multiplicative share)
+\\ second index level = agent id, price id
+Gamma = vector(n,a,matrix(n,k,i,j, ( prod(h=1,n,prod(d=j+1,k,alpha[h,d])) * prod(d=1,j-1,alpha[i,d]) * prod(h=1,i-1,alpha[h,j]) )^m[a][i,j] ))
+Delta = vector(n,a,matrix(n,k,i,j, ( prod(h=1,n,prod(d=j+1,k, beta[h,d])) * prod(d=1,j-1, beta[i,d]) * prod(h=1,i-1, beta[h,j]) )^m[a][i,j] ))
+
+\\\\\\\\\\\\
+\\ ROUND3
+\\\\\\\\\\\\
+
+\\ multiplicative shares (decryption)
+\\ first index level = owning agent id (multiplicative share)
+\\ second index level = agent id, price id
+Phi = vector(n,a,matrix(n,k,i,j, prod(h=1,n,Delta[h][i,j])^x[a] ))
+
+\\\\\\\\\\\\
+\\ EPILOG
+\\\\\\\\\\\\
+
+\\ winner matrix
+v = matrix(n,k,a,j, prod(i=1,n,Gamma[i][a,j]) / prod(i=1,n,Phi[i][a,j]) )
+
+vi = lift(v)
+
+print("bids are: ", bid)
+for(X=1,n, if(vecmin(vi[X,])==1, print("And the winner is ", X) ))