From 76facf0e80089dfe293ab765d242fd9992a36960 Mon Sep 17 00:00:00 2001
From: Tarak Ben Youssef <tarak.benyoussef@dapperlabs.com>
Date: Fri, 20 Nov 2020 21:01:03 -0800
Subject: [PATCH] improve erroring when bootstrapping keys are validated

---
 cmd/bootstrap/cmd/util.go |  2 +-
 crypto/bls.go             | 10 +++++-----
 crypto/ecdsa.go           |  8 ++++----
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/cmd/bootstrap/cmd/util.go b/cmd/bootstrap/cmd/util.go
index ed7d8757327..bbfc661ad00 100644
--- a/cmd/bootstrap/cmd/util.go
+++ b/cmd/bootstrap/cmd/util.go
@@ -37,7 +37,7 @@ func readJSON(path string, target interface{}) {
 	}
 	err = json.Unmarshal(dat, target)
 	if err != nil {
-		log.Fatal().Err(err).Msg("cannot unmarshal json in file")
+		log.Fatal().Err(err).Msgf("cannot unmarshal json in file %s", path)
 	}
 }
 
diff --git a/crypto/bls.go b/crypto/bls.go
index ca96b3abee7..622dd38d344 100644
--- a/crypto/bls.go
+++ b/crypto/bls.go
@@ -193,16 +193,16 @@ func (a *blsBLS12381Algo) decodePrivateKey(privateKeyBytes []byte) (PrivateKey,
 // This function includes a membership check in G2
 func (a *blsBLS12381Algo) decodePublicKey(publicKeyBytes []byte) (PublicKey, error) {
 	if len(publicKeyBytes) != pubKeyLengthBLSBLS12381 {
-		return nil, fmt.Errorf("the input length has to be equal to %d", pubKeyLengthBLSBLS12381)
+		return nil, fmt.Errorf("the input length has to be %d", pubKeyLengthBLSBLS12381)
 	}
 	var pk PubKeyBLSBLS12381
 	if readPointG2(&pk.point, publicKeyBytes) != nil {
-		return nil, errors.New("the input slice does not encode a public key")
+		return nil, errors.New("the input does not encode a BLS12-381 point")
 	}
-	if pk.point.checkMembershipG2() {
-		return &pk, nil
+	if !pk.point.checkMembershipG2() {
+		return nil, errors.New("the input does not encode a BLS12-381 point in the valid group")
 	}
-	return nil, errors.New("the public key is not a valid BLS12-381 curve key")
+	return &pk, nil
 }
 
 // PrKeyBLSBLS12381 is the private key of BLS using BLS12_381, it implements PrivateKey
diff --git a/crypto/ecdsa.go b/crypto/ecdsa.go
index 78b6430367a..0b158a51676 100644
--- a/crypto/ecdsa.go
+++ b/crypto/ecdsa.go
@@ -185,13 +185,13 @@ func (a *ecdsaAlgo) rawDecodePrivateKey(der []byte) (PrivateKey, error) {
 	n := a.curve.Params().N
 	nlen := bitsToBytes(n.BitLen())
 	if len(der) != nlen {
-		return nil, errors.New("raw private key size is not valid")
+		return nil, fmt.Errorf("input has incorrect %s key size", a.algo)
 	}
 	var d big.Int
 	d.SetBytes(der)
 
 	if d.Cmp(n) >= 0 {
-		return nil, errors.New("raw public key value is not valid")
+		return nil, fmt.Errorf("input is not a valid %s key", a.algo)
 	}
 
 	priv := goecdsa.PrivateKey{
@@ -214,7 +214,7 @@ func (a *ecdsaAlgo) rawDecodePublicKey(der []byte) (PublicKey, error) {
 	p := (a.curve.Params().P)
 	plen := bitsToBytes(p.BitLen())
 	if len(der) != 2*plen {
-		return nil, errors.New("raw public key size is not valid")
+		return nil, fmt.Errorf("input has incorrect %s key size", a.algo)
 	}
 	var x, y big.Int
 	x.SetBytes(der[:plen])
@@ -223,7 +223,7 @@ func (a *ecdsaAlgo) rawDecodePublicKey(der []byte) (PublicKey, error) {
 	// all the curves supported for now have a cofactor equal to 1,
 	// so that IsOnCurve guarantees the point is on the right subgroup.
 	if x.Cmp(p) >= 0 || y.Cmp(p) >= 0 || !a.curve.IsOnCurve(&x, &y) {
-		return nil, errors.New("raw public key value is not valid")
+		return nil, fmt.Errorf("input is not a valid %s key", a.algo)
 	}
 
 	pk := goecdsa.PublicKey{