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path: root/crypto/secp256k1/secp256_test.go
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// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package secp256k1

import (
    "bytes"
    "crypto/ecdsa"
    "crypto/elliptic"
    "crypto/rand"
    "encoding/hex"
    "testing"

    "github.com/ethereum/go-ethereum/common/math"
    "github.com/ethereum/go-ethereum/crypto/randentropy"
)

const TestCount = 1000

func generateKeyPair() (pubkey, privkey []byte) {
    key, err := ecdsa.GenerateKey(S256(), rand.Reader)
    if err != nil {
        panic(err)
    }
    pubkey = elliptic.Marshal(S256(), key.X, key.Y)
    return pubkey, math.PaddedBigBytes(key.D, 32)
}

func randSig() []byte {
    sig := randentropy.GetEntropyCSPRNG(65)
    sig[32] &= 0x70
    sig[64] %= 4
    return sig
}

// tests for malleability
// highest bit of signature ECDSA s value must be 0, in the 33th byte
func compactSigCheck(t *testing.T, sig []byte) {
    var b int = int(sig[32])
    if b < 0 {
        t.Errorf("highest bit is negative: %d", b)
    }
    if ((b >> 7) == 1) != ((b & 0x80) == 0x80) {
        t.Errorf("highest bit: %d bit >> 7: %d", b, b>>7)
    }
    if (b & 0x80) == 0x80 {
        t.Errorf("highest bit: %d bit & 0x80: %d", b, b&0x80)
    }
}

func TestSignatureValidity(t *testing.T) {
    pubkey, seckey := generateKeyPair()
    msg := randentropy.GetEntropyCSPRNG(32)
    sig, err := Sign(msg, seckey)
    if err != nil {
        t.Errorf("signature error: %s", err)
    }
    compactSigCheck(t, sig)
    if len(pubkey) != 65 {
        t.Errorf("pubkey length mismatch: want: 65 have: %d", len(pubkey))
    }
    if len(seckey) != 32 {
        t.Errorf("seckey length mismatch: want: 32 have: %d", len(seckey))
    }
    if len(sig) != 65 {
        t.Errorf("sig length mismatch: want: 65 have: %d", len(sig))
    }
    recid := int(sig[64])
    if recid > 4 || recid < 0 {
        t.Errorf("sig recid mismatch: want: within 0 to 4 have: %d", int(sig[64]))
    }
}

func TestInvalidRecoveryID(t *testing.T) {
    _, seckey := generateKeyPair()
    msg := randentropy.GetEntropyCSPRNG(32)
    sig, _ := Sign(msg, seckey)
    sig[64] = 99
    _, err := RecoverPubkey(msg, sig)
    if err != ErrInvalidRecoveryID {
        t.Fatalf("got %q, want %q", err, ErrInvalidRecoveryID)
    }
}

func TestSignAndRecover(t *testing.T) {
    pubkey1, seckey := generateKeyPair()
    msg := randentropy.GetEntropyCSPRNG(32)
    sig, err := Sign(msg, seckey)
    if err != nil {
        t.Errorf("signature error: %s", err)
    }
    pubkey2, err := RecoverPubkey(msg, sig)
    if err != nil {
        t.Errorf("recover error: %s", err)
    }
    if !bytes.Equal(pubkey1, pubkey2) {
        t.Errorf("pubkey mismatch: want: %x have: %x", pubkey1, pubkey2)
    }
}

func TestSignDeterministic(t *testing.T) {
    _, seckey := generateKeyPair()
    msg := make([]byte, 32)
    copy(msg, "hi there")

    sig1, err := Sign(msg, seckey)
    if err != nil {
        t.Fatal(err)
    }
    sig2, err := Sign(msg, seckey)
    if err != nil {
        t.Fatal(err)
    }
    if !bytes.Equal(sig1, sig2) {
        t.Fatal("signatures not equal")
    }
}

func TestRandomMessagesWithSameKey(t *testing.T) {
    pubkey, seckey := generateKeyPair()
    keys := func() ([]byte, []byte) {
        return pubkey, seckey
    }
    signAndRecoverWithRandomMessages(t, keys)
}

func TestRandomMessagesWithRandomKeys(t *testing.T) {
    keys := func() ([]byte, []byte) {
        pubkey, seckey := generateKeyPair()
        return pubkey, seckey
    }
    signAndRecoverWithRandomMessages(t, keys)
}

func signAndRecoverWithRandomMessages(t *testing.T, keys func() ([]byte, []byte)) {
    for i := 0; i < TestCount; i++ {
        pubkey1, seckey := keys()
        msg := randentropy.GetEntropyCSPRNG(32)
        sig, err := Sign(msg, seckey)
        if err != nil {
            t.Fatalf("signature error: %s", err)
        }
        if sig == nil {
            t.Fatal("signature is nil")
        }
        compactSigCheck(t, sig)

        // TODO: why do we flip around the recovery id?
        sig[len(sig)-1] %= 4

        pubkey2, err := RecoverPubkey(msg, sig)
        if err != nil {
            t.Fatalf("recover error: %s", err)
        }
        if pubkey2 == nil {
            t.Error("pubkey is nil")
        }
        if !bytes.Equal(pubkey1, pubkey2) {
            t.Fatalf("pubkey mismatch: want: %x have: %x", pubkey1, pubkey2)
        }
    }
}

func TestRecoveryOfRandomSignature(t *testing.T) {
    pubkey1, _ := generateKeyPair()
    msg := randentropy.GetEntropyCSPRNG(32)

    for i := 0; i < TestCount; i++ {
        // recovery can sometimes work, but if so should always give wrong pubkey
        pubkey2, _ := RecoverPubkey(msg, randSig())
        if bytes.Equal(pubkey1, pubkey2) {
            t.Fatalf("iteration: %d: pubkey mismatch: do NOT want %x: ", i, pubkey2)
        }
    }
}

func TestRandomMessagesAgainstValidSig(t *testing.T) {
    pubkey1, seckey := generateKeyPair()
    msg := randentropy.GetEntropyCSPRNG(32)
    sig, _ := Sign(msg, seckey)

    for i := 0; i < TestCount; i++ {
        msg = randentropy.GetEntropyCSPRNG(32)
        pubkey2, _ := RecoverPubkey(msg, sig)
        // recovery can sometimes work, but if so should always give wrong pubkey
        if bytes.Equal(pubkey1, pubkey2) {
            t.Fatalf("iteration: %d: pubkey mismatch: do NOT want %x: ", i, pubkey2)
        }
    }
}

// Useful when the underlying libsecp256k1 API changes to quickly
// check only recover function without use of signature function
func TestRecoverSanity(t *testing.T) {
    msg, _ := hex.DecodeString("ce0677bb30baa8cf067c88db9811f4333d131bf8bcf12fe7065d211dce971008")
    sig, _ := hex.DecodeString("90f27b8b488db00b00606796d2987f6a5f59ae62ea05effe84fef5b8b0e549984a691139ad57a3f0b906637673aa2f63d1f55cb1a69199d4009eea23ceaddc9301")
    pubkey1, _ := hex.DecodeString("04e32df42865e97135acfb65f3bae71bdc86f4d49150ad6a440b6f15878109880a0a2b2667f7e725ceea70c673093bf67663e0312623c8e091b13cf2c0f11ef652")
    pubkey2, err := RecoverPubkey(msg, sig)
    if err != nil {
        t.Fatalf("recover error: %s", err)
    }
    if !bytes.Equal(pubkey1, pubkey2) {
        t.Errorf("pubkey mismatch: want: %x have: %x", pubkey1, pubkey2)
    }
}

func BenchmarkSign(b *testing.B) {
    _, seckey := generateKeyPair()
    msg := randentropy.GetEntropyCSPRNG(32)
    b.ResetTimer()

    for i := 0; i < b.N; i++ {
        Sign(msg, seckey)
    }
}

func BenchmarkRecover(b *testing.B) {
    msg := randentropy.GetEntropyCSPRNG(32)
    _, seckey := generateKeyPair()
    sig, _ := Sign(msg, seckey)
    b.ResetTimer()

    for i := 0; i < b.N; i++ {
        RecoverPubkey(msg, sig)
    }
}