a≡b (mod c)

a≡b (mod c)　は a-bがcで割り切れること。
10≡0 (mod 5)
14≡5 (mod 3)
13≡-3 (mod 2)

from Crypto.Util.number import inverse
def message_value(message):
	message = bits_to_string(pad_to_block(convert_to_bits(message), 8))
	return cutchoose.bill_value(message)

def remove_nonce(bill, nonce):
	big_nonce = pow(nonce, cutchoose.BANK_PUBLIC_KEY[0], cutchoose.BANK_PUBLIC_KEY[1])
	nonce_inverse = inverse(big_nonce, cutchoose.BANK_PUBLIC_KEY[1])
	message = (bill * nonce_inverse) % cutchoose.BANK_PUBLIC_KEY[1]
	return message

def _verify(bills, nonces, value):
	for bill, nonce in zip(bills, nonces):
		message = remove_nonce(Bill, nonce)
		test_value = message_value(message)
		if test_value != value:
			return False