deriving an ethereum address from a nostr pubkey or checking if they match

go.mod

module github.com/fiatjaf/ethereum-nostr

go 1.20

require (
	github.com/btcsuite/btcd/btcec/v2 v2.3.2
	github.com/nbd-wtf/go-nostr v0.19.5
	golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
)

require (
	github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1 // indirect
	github.com/decred/dcrd/crypto/blake256 v1.0.0 // indirect
	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 // indirect
	github.com/gobwas/httphead v0.1.0 // indirect
	github.com/gobwas/pool v0.2.1 // indirect
	github.com/gobwas/ws v1.2.0 // indirect
	github.com/josharian/intern v1.0.0 // indirect
	github.com/mailru/easyjson v0.7.7 // indirect
	github.com/puzpuzpuz/xsync v1.5.2 // indirect
	github.com/tidwall/gjson v1.14.4 // indirect
	github.com/tidwall/match v1.1.1 // indirect
	github.com/tidwall/pretty v1.2.0 // indirect
	golang.org/x/exp v0.0.0-20221106115401-f9659909a136 // indirect
	golang.org/x/net v0.10.0 // indirect
	golang.org/x/sys v0.10.0 // indirect
)

go.sum

github.com/btcsuite/btcd/btcec/v2 v2.3.2 h1:5n0X6hX0Zk+6omWcihdYvdAlGf2DfasC0GMf7DClJ3U=
github.com/btcsuite/btcd/btcec/v2 v2.3.2/go.mod h1:zYzJ8etWJQIv1Ogk7OzpWjowwOdXY1W/17j2MW85J04=
github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1 h1:q0rUy8C/TYNBQS1+CGKw68tLOFYSNEs0TFnxxnS9+4U=
github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1/go.mod h1:7SFka0XMvUgj3hfZtydOrQY2mwhPclbT2snogU7SQQc=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/decred/dcrd/crypto/blake256 v1.0.0 h1:/8DMNYp9SGi5f0w7uCm6d6M4OU2rGFK09Y2A4Xv7EE0=
github.com/decred/dcrd/crypto/blake256 v1.0.0/go.mod h1:sQl2p6Y26YV+ZOcSTP6thNdn47hh8kt6rqSlvmrXFAc=
github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1 h1:YLtO71vCjJRCBcrPMtQ9nqBsqpA1m5sE92cU+pd5Mcc=
github.com/decred/dcrd/dcrec/secp256k1/v4 v4.0.1/go.mod h1:hyedUtir6IdtD/7lIxGeCxkaw7y45JueMRL4DIyJDKs=
github.com/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
github.com/gobwas/pool v0.2.1/go.mod h1:q8bcK0KcYlCgd9e7WYLm9LpyS+YeLd8JVDW6WezmKEw=
github.com/gobwas/ws v1.2.0 h1:u0p9s3xLYpZCA1z5JgCkMeB34CKCMMQbM+G8Ii7YD0I=
github.com/gobwas/ws v1.2.0/go.mod h1:hRKAFb8wOxFROYNsT1bqfWnhX+b5MFeJM9r2ZSwg/KY=
github.com/josharian/intern v1.0.0 h1:vlS4z54oSdjm0bgjRigI+G1HpF+tI+9rE5LLzOg8HmY=
github.com/josharian/intern v1.0.0/go.mod h1:5DoeVV0s6jJacbCEi61lwdGj/aVlrQvzHFFd8Hwg//Y=
github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
github.com/nbd-wtf/go-nostr v0.19.5 h1:BdNTIKVJOyxRJwxzlblJqV7sja4pmCYFBXQdCDVowhI=
github.com/nbd-wtf/go-nostr v0.19.5/go.mod h1:F9y6+M8askJCjilLgMC3rD0moA6UtG1MCnyClNYXeys=
github.com/puzpuzpuz/xsync v1.5.2 h1:yRAP4wqSOZG+/4pxJ08fPTwrfL0IzE/LKQ/cw509qGY=
github.com/puzpuzpuz/xsync v1.5.2/go.mod h1:K98BYhX3k1dQ2M63t1YNVDanbwUPmBCAhNmVrrxfiGg=
github.com/tidwall/gjson v1.14.4 h1:uo0p8EbA09J7RQaflQ1aBRffTR7xedD2bcIVSYxLnkM=
github.com/tidwall/gjson v1.14.4/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
github.com/tidwall/match v1.1.1 h1:+Ho715JplO36QYgwN9PGYNhgZvoUSc9X2c80KVTi+GA=
github.com/tidwall/match v1.1.1/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
github.com/tidwall/pretty v1.2.0 h1:RWIZEg2iJ8/g6fDDYzMpobmaoGh5OLl4AXtGUGPcqCs=
github.com/tidwall/pretty v1.2.0/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9 h1:psW17arqaxU48Z5kZ0CQnkZWQJsqcURM6tKiBApRjXI=
golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
golang.org/x/exp v0.0.0-20221106115401-f9659909a136 h1:Fq7F/w7MAa1KJ5bt2aJ62ihqp9HDcRuyILskkpIAurw=
golang.org/x/exp v0.0.0-20221106115401-f9659909a136/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
golang.org/x/net v0.10.0 h1:X2//UzNDwYmtCLn7To6G58Wr6f5ahEAQgKNzv9Y951M=
golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.10.0 h1:SqMFp9UcQJZa+pmYuAKjd9xq1f0j5rLcDIk0mj4qAsA=
golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

main.go

package main

import (
	"encoding/hex"
	"fmt"
	"strings"

	"github.com/btcsuite/btcd/btcec/v2"
	"github.com/nbd-wtf/go-nostr"
	"golang.org/x/crypto/sha3"
)

func main() {
	sk := "245ec11906ea42186381c6f18d248e95e532ce1de517f2b32768fda20b5c61bd"
	ethAddress := "0x922307C3B62D2f31280d49AfE52CD8E5C06d761E"

	pk, err := nostr.GetPublicKey(sk)
	if err != nil {
		panic(err)
	}

	fmt.Println("root secret key:\t", sk)
	fmt.Println("nostr (x-only) pubkey:\t", pk)
	fmt.Println("ethereum address:\t", ethAddress)
	fmt.Println("does it match?\t\t", doesNostrKeyCorrespondToEthereumAddress(pk, ethAddress))
}

func doesNostrKeyCorrespondToEthereumAddress(nostrPubKey string, ethAddress string) bool {
	ethAddress = strings.ToLower(ethAddress)
	ethAddress = strings.TrimPrefix(ethAddress, "0x")

	for _, prefix := range []string{"02", "03"} {
		pkBytes, err := hex.DecodeString(prefix + nostrPubKey)
		if err != nil {
			continue
		}

		fullPk, err := btcec.ParsePubKey(pkBytes)
		if err != nil {
			continue
		}

		uncompressed := fullPk.SerializeUncompressed()
		hash := sha3.NewLegacyKeccak256()
		hash.Write(uncompressed[1:])
		res := hash.Sum(nil)
		resH := hex.EncodeToString(res)

		if resH[24:64] == ethAddress {
			return true
		}
	}
	return false
}