v3.6.0 breaks ethereumjs-devp2p

[vpulim]

Peers are no longer able to successfully handshake.

ecdhUnsafe() seems to be returning different values between 3.5.2 and 3.6.0

[fanatid]

wow, do you have data for reproducing this issue?

[vpulim]

Sure, here's some test code that I ran on 3.5.2 and 3.6.0 and got different results:

const secp256k1 = require('./index')
const publicKey = Buffer.from('03d0d06028880fac08fc7d481a87fca5845be7921ca83b49ed4697ca5c62b701c9', 'hex')
const privateKey = Buffer.from('9658d24d521e8f2d460722de887792441907079b4e76cdc341c3732600900477', 'hex')
console.log(secp256k1.ecdhUnsafe(publicKey, privateKey, true).toString('hex'))

3.5.2:

>> 033a353c2b6934e8746c363219eb718477a87cf5565eaa920db67258990b444d94

3.6.0:

>> 03944d440b995872b60d92aa5e56f57ca8778471eb1932366c74e834692b3c353a

NOTE: The keys were generated using test/util.js:

const privateKey = util.getPrivateKey()
const publicKey = util.getPublicKey(privateKey).compressed

Also, I ran the test using node LTS versions 6.16.0, 8.15.0 and 10.15.0 and all generated the same results.