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spend_transaction.py
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spend_transaction.py
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# Spend transaction
import address
import bpplus
import chaum
import coin
import dumb25519
from dumb25519 import Point, Scalar, PointVector, ScalarVector, hash_to_scalar
import parallel
import schnorr
class ProtocolParameters:
def __init__(self,F,G,H,U,value_bytes,memo_bytes,n,m):
if not isinstance(F,Point):
raise TypeError('Bad type for parameter F!')
if not isinstance(G,Point):
raise TypeError('Bad type for parameter G!')
if not isinstance(H,Point):
raise TypeError('Bad type for parameter H!')
if not isinstance(U,Point):
raise TypeError('Bad type for parameter U!')
if not isinstance(value_bytes,int) or value_bytes < 1:
raise ValueError('Bad type or value for parameter value_bytes!')
if not isinstance(memo_bytes,int) or memo_bytes < 1:
raise ValueError('Bad type or value for parameter value_bytes!')
if not isinstance(n,int) or n < 1:
raise ValueError('Bad type or value for parameter n!')
if not isinstance(m,int) or m < 1:
raise ValueError('Bad type or value for parameter m!')
self.F = F
self.G = G
self.H = H
self.U = U
self.value_bytes = value_bytes
self.memo_bytes = memo_bytes
self.n = n
self.m = m
class SpendTransaction:
def __init__(self,params,full,spend,inputs,indexes,fee,outputs):
if not isinstance(params,ProtocolParameters):
raise TypeError('Bad type for parameters!')
if not isinstance(full,address.FullViewKey):
raise TypeError('Bad type for full view key!')
if not isinstance(spend,address.SpendKey):
raise TypeError('Bad type for spend key!')
for input in inputs:
if not isinstance(input,coin.Coin):
raise TypeError('Bad type for input coin!')
for l in indexes:
if not isinstance(l,int) or l < 0 or l >= params.n**params.m:
raise ValueError('Bad type or value for spend index!')
if not inputs[l].recovered:
raise ValueError('Input coin is not recovered!')
if not isinstance(fee,int) or fee < 0 or fee.bit_length() > params.value_bytes:
raise ValueError('Bad type or value for fee!')
for output in outputs:
if not isinstance(output,coin.Coin):
raise TypeError('Bad type for output coin!')
if not output.is_output:
raise ValueError('Output coin is not flagged as output!')
w = len(indexes)
t = len(outputs)
self.inputs = inputs # input cover set
self.outputs = outputs # output coins
self.fee = fee # transaction fee
self.S1 = PointVector() # serial number commitment offsets
self.C1 = PointVector() # value commitment offsets
self.T = PointVector() # tags
self.parallel = [] # parallel one-of-many proofs
# Spends
for u in range(w):
input = inputs[indexes[u]]
# Serial number commitment offset
self.S1.append(input.delegation.S1)
self.C1.append(input.delegation.C1)
# Tag
self.T.append(input.T)
# Parallel one-of-many proof
self.parallel.append(parallel.prove(
parallel.ParallelStatement(
parallel.ParallelParameters(params.H,params.n,params.m),
PointVector([input.S for input in inputs]),
PointVector([input.C for input in inputs]),
self.S1[u],
self.C1[u]
),
parallel.ParallelWitness(
indexes[u],
input.delegation.s1,
input.delegation.c1,
)
))
# Balance statement input value
b_st = dumb25519.Z
for u in range(w):
b_st += self.C1[u]
for j in range(t):
b_st -= outputs[j].C
b_st -= Scalar(fee)*params.G
# Balance witness
b_w = Scalar(0)
for u in range(w):
input = inputs[indexes[u]]
b_w += hash_to_scalar('val1',input.delegation.id,input.s,full.s1,full.s2)
for j in range(t):
b_w -= hash_to_scalar('val',outputs[j].k*outputs[j].Q1)
# Balance proof
self.balance = schnorr.prove(
schnorr.SchnorrStatement(schnorr.SchnorrParameters(params.H),b_st),
schnorr.SchnorrWitness(b_w)
)
# Aggregated modified Chaum-Pedersen proof
mu = hash_to_scalar(
self.inputs,
self.outputs,
self.fee,
self.S1,
self.C1,
self.T,
self.parallel,
self.balance
)
chaum_x = ScalarVector([inputs[indexes[u]].s for u in range(w)])
chaum_y = ScalarVector([spend.r]*w)
chaum_z = ScalarVector([Scalar(0) - hash_to_scalar('ser1',inputs[indexes[u]].delegation.id,inputs[indexes[u]].s,full.s1,full.s2) for u in range(w)])
self.chaum = chaum.prove(
chaum.ChaumStatement(chaum.ChaumParameters(params.F,params.G,params.H,params.U),mu,self.S1,self.T),
chaum.ChaumWitness(chaum_x,chaum_y,chaum_z)
)
def verify(self,params,tags=None):
if not isinstance(params,ProtocolParameters):
raise TypeError('Bad type for parameters!')
# Check tag uniqueness
for tag in self.T:
if tags is not None and tag in tags:
raise ValueError('Tag has been seen before!')
# Check fee
if self.fee < 0 or self.fee.bit_length() > params.value_bytes:
raise ValueError('Bad value for transaction fee!')
w = len(self.T)
t = len(self.outputs)
mu = hash_to_scalar(
self.inputs,
self.outputs,
self.fee,
self.S1,
self.C1,
self.T,
self.parallel,
self.balance
)
# Check input proofs
for u in range(w):
parallel.verify(
parallel.ParallelStatement(
parallel.ParallelParameters(params.H,params.n,params.m),
PointVector([input.S for input in self.inputs]),
PointVector([input.C for input in self.inputs]),
self.S1[u],
self.C1[u]
),
self.parallel[u]
)
chaum.verify(
chaum.ChaumStatement(chaum.ChaumParameters(params.F,params.G,params.H,params.U),mu,self.S1,self.T),
self.chaum
)
# Check output proofs
for j in range(t):
bpplus.verify(
[bpplus.RangeStatement(bpplus.RangeParameters(params.G,params.H,8*params.value_bytes),PointVector([self.outputs[j].C]))],
[self.outputs[j].range]
)
# Check balance
b_st = dumb25519.Z
for u in range(w):
b_st += self.C1[u]
for j in range(t):
b_st -= self.outputs[j].C
b_st -= Scalar(self.fee)*params.G
schnorr.verify(
schnorr.SchnorrStatement(schnorr.SchnorrParameters(params.H),b_st),
self.balance
)