def reconstruct_shamir(
shares,
i,
t=0
): #Do we have to mention which additive share these backups belong to? i.e. need for 'i'?
'''Verify first using VSS and then reconstruct, i is index of the additive share for vss_p, etc'''
vss_q = fileOp.read_list("FvssQ")[0]
vss_p = fileOp.read_list("FvssP")[0]
gen = fileOp.read_list("FvssGen")[0]
commitment_list = fileOp.read_list("FvssCommitmentList")[0]
res = True
for si in shares:
if RSAFeldmanVSS.verify_share(si, gen[i], vss_p[i],
commitment_list[i]) == False:
res = False
break
if res == False:
print("Share:", si, "invalid")
raise Exception("Backup Reconstruction Failed")
return
else:
return (ShamirSS.tncombine(shares, vss_q[i], t))
def threshold_additive_shares(shares, t, n):
'''Divides all elements in the shares list into t-n threshold shares using Feldman VSS into n sub-shares with threshold t'''
global sub_shares
global vss_p
global vss_q
global gen
global commitment_list
sub_shares = []
commitment_list = []
vss_p = []
vss_q = []
gen = []
for i in shares:
feld = RSAFeldmanVSS.feldmanvss(t, n, i)
sub_shares.append(feld[0]) #Generate using VSS
commitment_list.append(feld[1])
vss_p.append(feld[2])
vss_q.append(feld[3])
gen.append(feld[4])
return
def threshold_additive_shares():
'''Divides all elements in the shares list into t-n threshold shares using Feldman VSS into n sub-shares with threshold t'''
shares = fileOp.read_list("FadditiveShares")
t, n = 3, 5 #Generates a (3,5) threshold scheme FIX: Read from file
sub_shares, commitment_list = [], []
vss_p, vss_q, gen = [], [], []
for i in shares:
feld = RSAFeldmanVSS.feldmanvss(t, n, i)
sub_shares.append(feld[0]) #Generate using VSS
commitment_list.append(feld[1])
vss_p.append(feld[2])
vss_q.append(feld[3])
gen.append(feld[4])
fileOp.write_list("FvssP", vss_p)
fileOp.write_list("FvssQ", vss_q)
fileOp.write_list("FvssGen", gen)
fileOp.write_list("FvssSubShares", sub_shares)
fileOp.write_list("FvssCommitmentList", commitment_list)
return