From d149077543e587d09edac3f94e77365a49fc0b06 Mon Sep 17 00:00:00 2001 From: Pavol Rusnak Date: Sun, 9 Feb 2014 00:55:38 +0100 Subject: [PATCH] canonical versions of sigencode methods these enforce low S values, by negating the value (modulo the order) if above order/2 --- ecdsa/util.py | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/ecdsa/util.py b/ecdsa/util.py index 816c62f1..06e4629e 100644 --- a/ecdsa/util.py +++ b/ecdsa/util.py @@ -197,6 +197,24 @@ def sigencode_string(r, s, order): def sigencode_der(r, s, order): return der.encode_sequence(der.encode_integer(r), der.encode_integer(s)) +# canonical versions of sigencode methods +# these enforce low S values, by negating the value (modulo the order) if above order/2 +# see CECKey::Sign() https://github.com/bitcoin/bitcoin/blob/master/src/key.cpp#L214 +def sigencode_strings_canonize(r, s, order): + if s > order / 2: + s = order - s + return sigencode_strings(r, s, order) + +def sigencode_string_canonize(r, s, order): + if s > order / 2: + s = order - s + return sigencode_string(r, s, order) + +def sigencode_der_canonize(r, s, order): + if s > order / 2: + s = order - s + return sigencode_der(r, s, order) + def sigdecode_string(signature, order): l = orderlen(order)