HS512 support

[tsn77130]

Hi team, as said by in issue #11, thanks for this great job and associated documentation.
I was wondering if there is any chance you also add support for HS512 ?

thanks

[NickMRamirez]

@tsn77130 I've added a new branch called issue-13 that should work for HS512, but since Auth0 only supports HS256 I will need to find another auth provider to use for testing.

To expedite it, can you test it on your end and let me know if it works?

1. Checkout the issue-13 branch
2. Replace /usr/local/share/lua/5.3/jwtverify.lua with the file from that branch
3. In the global section of haproxy.cfg, add your HMAC secret.

for example:

setenv OAUTH_HMAC_SECRET E57lT71DHOHK1eeOlMjatvUtUg6ejFZ8

Then test the client credential auth flow.

[tsn77130]

@NickMRamirez Just tested your dev, it works great with HS512

2021-06-03T15:12:42.503859+02:00 intweb10 haproxy[9317]: Decoded JWT header: { ["typ"] = JWT,["alg"] = HS512,} 
2021-06-03T15:12:42.503874+02:00 intweb10 haproxy[9317]: Decoded JWT payload: { ["debug"] = false,["roles"] = { [1] = retailer,} ,["iat"] = 1622725351,["exp"] = 1622811751,["aud"] = api.xx.com,["sub"] = 7170,["iss"] = api.xx.com,["retailer_id"] = 134,["login"] = user44} 
2021-06-03T15:12:42.503904+02:00 intweb10 haproxy[9317]: req.authorized = true

Thanks a lot for that

[NickMRamirez]

Great! I will merge this change.