def get_params(uname, A, s):
try:
if uname and A:
b = util.get_random_number()
p = client_store[uname]
x = util.H(s, uname, p)
N, g = util.get_ng()
v = pow(g, x, N)
k = util.get_K()
B = (k*v + pow(g, b, N)) % N
return B, v, b
else:
print(' Please enter valid username and password ')
except Exception as e:
print(' Invalid username password entered... ')
def compute_shared_key(A, msg, username, password, a):
try:
if(msg.has_key('SIGNED_SALT') and msg.has_key('SIGNED_B') and msg.has_key('SALT') and msg.has_key('B')):
signed_salt = msg['SIGNED_SALT']
signed_B = msg['SIGNED_B']
salt = msg['SALT']
B = msg['B']
util.verify_signature(SERVER_KEY, signed_salt, str(salt).encode())
util.verify_signature(SERVER_KEY, signed_B, str(B).encode())
else:
raise Exception('Did not found the expected keys for Salt and B')
except Exception as e:
print "An error occured while verifying the digital signature"
raise
u = util.H(A, B)
x = util.H(salt, username, password)
k = util.get_K()
key = util.get_client_shared_key(B, k, x, a, u)
return key
