Problem with Fourq? about circl HOT 12 CLOSED

As far as I remember FourQ uses MULXQ instruction which may not be supported on your CPU.

The fix which worked for me was to first check if CPU supports MULX and, if not, fallback to unoptimized implementation which doesn't use assembly (I think I needed to add non-assembly implementation to my local clone).

Obviously using newer CPU "solves" the issue :)

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You are correct. It was using the old version of the code. I had to remove the old version of the Circl library, and fully re-download. It works perfectly now:

Online demo

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@billbuchanan we will investigate this issue. In the meantime, which Go version did you use? Did you see this error with other keys, or it is a consistent error for any key? Which CPU model are you using, e.g. Core i5-4000x?

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I am using Go 1.12.6 windows/amd64

I have managed to get all of the other key exchange methods to work (post-quantum, X25519, X448, and so on), but I get an exception with Fourq using a basic multiplication of the base point (I tried lots of different key value, from simple to random, but still get an exception). My CPU is AMD Phenom II X6 1055T, 2.80 GHz.

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Thanks for this. Do you have instructions on building for the non-assembly implementation?

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I am working on a patch, it will be released this week.

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Thank you so much. Excellent support, and love the library.

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The PR #96 has added support for legacy multiplication instructions.
Let us know if some other issues arise.

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Thanks for the update. I now get the error of:
\github.com\cloudflare\circl\ecc\fourq\fp_amd64.s:50: unrecognized instruction "_fpMulLeg"
asm: assembly of github.com\cloudflare\circl\ecc\fourq\fp_amd64.s failed

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@billbuchanan
I could not reproduce that failure. I tried using go1.12.6, but in a linux machine.
Does that error happen during compilation or running time?

I recommend you to update Go to a more recent version. Also, make sure to clean compilation cache using go clean -cache

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I can get it to work here:

https://repl.it/@billbuchanan/gofourq

But on my server, I get a runtime error:
c:>fourq.exe
Secret [250 133 245 228 228 163 21 170 121 63 215 199 226 215 181 104 55 156 72
117 141 179 146 105 216 0 226 124 140 33 131 80]

Exception 0xc000001d 0x0 0x0 0x4b2758
PC=0x4b2758

github.com/cloudflare/circl/ecc/fourq.doubleAsm(0xc000085d10)
d:/go/src/src/github.com/cloudflare/circl/ecc/fourq/point_amd64.s:8 +0x8
8
github.com/cloudflare/circl/ecc/fourq.(*pointR1).double(...)
d:/go/src/src/github.com/cloudflare/circl/ecc/fourq/point_amd64.go:24
github.com/cloudflare/circl/ecc/fourq.(*pointR1).ScalarBaseMult(0xc000085d10, 0x
c000058140)
d:/go/src/src/github.com/cloudflare/circl/ecc/fourq/point.go:190 +0x284
github.com/cloudflare/circl/ecc/fourq.(*Point).ScalarBaseMult(0xc000085dd0, 0xc0
00058140)
d:/go/src/src/github.com/cloudflare/circl/ecc/fourq/curve.go:82 +0x70
main.KeyGen(0xc000085ec8, 0xc000058140)
c:/Python27/godir/fourq.go:22 +0x53
main.main()
c:/Python27/godir/fourq.go:49 +0x1d0
rax 0x0
rbx 0x0
rcx 0x0
rdi 0xc000085d10
rsi 0x0
rbp 0xc000085cf0
rsp 0xc000085b28
r8 0x0
r9 0x0
r10 0x0
r11 0x0
r12 0x6c2a26
r13 0x4db6e0
r14 0x0
r15 0x0
rip 0x4b2758
rflags 0x10246
cs 0x33
fs 0x53
gs 0x2b

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Please take a look on your go.mod file, it should point to the master version rather than to v1.0.0.

File: go.mod

module main

go 1.13

require github.com/cloudflare/circl master

Note that the error message still points to the function doubleAsm, which was removed after you reported us the initial bug.

github.com/cloudflare/circl/ecc/fourq.doubleAsm(0xc000085d10)
d:/go/src/src/github.com/cloudflare/circl/ecc/fourq/point_amd64.s:8 +0x8

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