Commit Graph

10 Commits

Author SHA1 Message Date
Marius van der Wijden
0703ef62d3
crypto/secp256k1: fix undefined behavior in BitCurve.Add (#22621)
This commit changes the behavior of BitCurve.Add to be more inline
with btcd. It fixes two different bugs:

1) When adding a point at infinity to another point, the other point
   should be returned. While this is undefined behavior, it is better
   to be more inline with the go standard library.
   Thus (0,0) + (a, b) = (a,b)

2) Adding the same point to itself produced the point at infinity.
   This is incorrect, now doubleJacobian is used to correctly calculate it.
   Thus (a,b) + (a,b) == 2* (a,b) and not (0,0) anymore.

The change also adds a differential fuzzer for Add, testing it against btcd.

Co-authored-by: Felix Lange <fjl@twurst.com>
2021-05-27 13:30:25 +02:00
Abd ar-Rahman Hamidi
db87223269
crypto/secp256k1: add checking z sign in affineFromJacobian (#18419)
The z == 0 check is hit whenever we Add two points with the same x1/x2
coordinate. crypto/elliptic uses the same check in their affineFromJacobian
function. This change does not affect block processing or tx signature verification
in any way, because it does not use the Add or Double methods.
2020-11-17 11:47:17 +01:00
Shuai Qi
e57e4571d3 crypto/secp256k1: Fix invalid document link (#18297) 2018-12-13 10:25:13 +01:00
Péter Szilágyi
d9575e92fc crypto/secp256k1: remove external LGPL dependencies (#17239) 2018-07-26 13:33:13 +02:00
kiel barry
ba975dc093 crypto: fix golint warnings (#16710) 2018-05-09 01:17:09 +02:00
David Huie
d1af4e1a9e crypto/secp256k1: catch curve parameter parse errors (#16392) 2018-04-03 17:12:00 +02:00
Felix Lange
c6069a627c
crypto, crypto/secp256k1: add CompressPubkey (#15626)
This adds the inverse to DecompressPubkey and improves a few minor
details in crypto/secp256k1.
2017-12-15 10:40:09 +01:00
Felix Lange
5f7826270c all: unify big.Int zero checks, use common/math in more places (#3716)
* common/math: optimize PaddedBigBytes, use it more

name              old time/op    new time/op    delta
PaddedBigBytes-8    71.1ns ± 5%    46.1ns ± 1%  -35.15%  (p=0.000 n=20+19)

name              old alloc/op   new alloc/op   delta
PaddedBigBytes-8     48.0B ± 0%     32.0B ± 0%  -33.33%  (p=0.000 n=20+20)

* all: unify big.Int zero checks

Various checks were in use. This commit replaces them all with Int.Sign,
which is cheaper and less code.

eg templates:

    func before(x *big.Int) bool { return x.BitLen() == 0 }
    func after(x *big.Int) bool  { return x.Sign() == 0 }

    func before(x *big.Int) bool { return x.BitLen() > 0 }
    func after(x *big.Int) bool  { return x.Sign() != 0 }

    func before(x *big.Int) int { return x.Cmp(common.Big0) }
    func after(x *big.Int) int  { return x.Sign() }

* common/math, crypto/secp256k1: make ReadBits public in package math
2017-02-28 15:09:11 +01:00
Felix Lange
e0ceeab0d1 crypto/secp256k1: update to github.com/bitcoin-core/secp256k1 @ 9d560f9 (#3544)
- Use defined constants instead of hard-coding their integer value.
- Allocate secp256k1 structs on the C stack instead of converting []byte
- Remove dead code
2017-01-12 21:29:11 +01:00
Gustav Simonsson
c8ad64f33c crypto, crypto/ecies, crypto/secp256k1: libsecp256k1 scalar mult
thanks to Felix Lange (fjl) for help with design & impl
2015-11-30 13:43:32 +01:00