schnorr: Rename error codes to better match reality.

This renames some error codes to more closely match the failure as
follows:

- ErrBadInputSize -> ErrInvalidHashLen
- ErrInputValue -> ErrPrivateKeyIsZero
- ErrPointNotOnCurve -> ErrPubKeyNotOnCurve
- ErrBadSigRYValue -> ErrSigRYIsOdd
- ErrBadSigRNotOnCurve -> ErrSigRNotOnCurve

dcrec/secp256k1/schnorr/error.go

@@ -1,5 +1,5 @@
 // Copyright (c) 2014 Conformal Systems LLC.
-// Copyright (c) 2015-2016 The Decred developers
+// Copyright (c) 2015-2020 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -16,27 +16,28 @@ type ErrorCode int
 
 // These constants are used to identify a specific RuleError.
 const (
-	// ErrBadInputSize indicates that input to a signature was of the wrong size.
-	ErrBadInputSize ErrorCode = iota
+	// ErrInvalidHashLen indicates that the input hash to sign or verify is not
+	// the required length.
+	ErrInvalidHashLen ErrorCode = iota
 
-	// ErrInputValue indicates that the value of an input was wrong (e.g. zero).
-	ErrInputValue
+	// ErrPrivateKeyIsZero indicates an attempt was made to sign a message with
+	// a private key that is equal to zero.
+	ErrPrivateKeyIsZero
 
-	// ErrSchnorrHashValue indicates that the hash of (R || m) was too large
-	// and so a new k value (nonce) should be used.
+	// ErrSchnorrHashValue indicates that the hash of (R || m) was too large and
+	// so a new nonce should be used.
 	ErrSchnorrHashValue
 
-	// ErrPointNotOnCurve indicates that a point was not on the given
-	// elliptic curve.
-	ErrPointNotOnCurve
+	// ErrPubKeyNotOnCurve indicates that a point was not on the given elliptic
+	// curve.
+	ErrPubKeyNotOnCurve
 
-	// ErrBadSigRYValue indicates that the calculated Y value of R was odd,
-	// which is not allowed.
-	ErrBadSigRYValue
+	// ErrSigRYIsOdd indicates that the calculated Y value of R was odd.
+	ErrSigRYIsOdd
 
-	// ErrBadSigRNotOnCurve indicates that the calculated or given point R for some
+	// ErrSigRNotOnCurve indicates that the calculated or given point R for some
 	// signature was not on the curve.
-	ErrBadSigRNotOnCurve
+	ErrSigRNotOnCurve
 
 	// ErrUnequalRValues indicates that the calculated point R for some
 	// signature was not the same as the given R value for the signature.
@@ -65,17 +66,17 @@ const (
 
 // Map of ErrorCode values back to their constant names for pretty printing.
 var errorCodeStrings = map[ErrorCode]string{
-	ErrBadInputSize:      "ErrBadInputSize",
-	ErrInputValue:        "ErrInputValue",
-	ErrSchnorrHashValue:  "ErrSchnorrHashValue",
-	ErrPointNotOnCurve:   "ErrPointNotOnCurve",
-	ErrBadSigRYValue:     "ErrBadSigRYValue",
-	ErrBadSigRNotOnCurve: "ErrBadSigRNotOnCurve",
-	ErrUnequalRValues:    "ErrUnequalRValues",
-	ErrSigTooShort:       "ErrSigTooShort",
-	ErrSigTooLong:        "ErrSigTooLong",
-	ErrSigRTooBig:        "ErrSigRTooBig",
-	ErrSigSTooBig:        "ErrSigSTooBig",
+	ErrInvalidHashLen:   "ErrInvalidHashLen",
+	ErrPrivateKeyIsZero: "ErrPrivateKeyIsZero",
+	ErrSchnorrHashValue: "ErrSchnorrHashValue",
+	ErrPubKeyNotOnCurve: "ErrPubKeyNotOnCurve",
+	ErrSigRYIsOdd:       "ErrSigRYIsOdd",
+	ErrSigRNotOnCurve:   "ErrSigRNotOnCurve",
+	ErrUnequalRValues:   "ErrUnequalRValues",
+	ErrSigTooShort:      "ErrSigTooShort",
+	ErrSigTooLong:       "ErrSigTooLong",
+	ErrSigRTooBig:       "ErrSigRTooBig",
+	ErrSigSTooBig:       "ErrSigSTooBig",
 }
 
 // String returns the ErrorCode as a human-readable name.

dcrec/secp256k1/schnorr/error_test.go

@@ -15,12 +15,12 @@ func TestErrorCodeStringer(t *testing.T) {
 		in   ErrorCode
 		want string
 	}{
-		{ErrBadInputSize, "ErrBadInputSize"},
-		{ErrInputValue, "ErrInputValue"},
+		{ErrInvalidHashLen, "ErrInvalidHashLen"},
+		{ErrPrivateKeyIsZero, "ErrPrivateKeyIsZero"},
 		{ErrSchnorrHashValue, "ErrSchnorrHashValue"},
-		{ErrPointNotOnCurve, "ErrPointNotOnCurve"},
-		{ErrBadSigRYValue, "ErrBadSigRYValue"},
-		{ErrBadSigRNotOnCurve, "ErrBadSigRNotOnCurve"},
+		{ErrPubKeyNotOnCurve, "ErrPubKeyNotOnCurve"},
+		{ErrSigRYIsOdd, "ErrSigRYIsOdd"},
+		{ErrSigRNotOnCurve, "ErrSigRNotOnCurve"},
 		{ErrUnequalRValues, "ErrUnequalRValues"},
 		{ErrSigTooShort, "ErrSigTooShort"},
 		{ErrSigTooLong, "ErrSigTooLong"},
@@ -76,53 +76,53 @@ func TestErrorCodeIsAs(t *testing.T) {
 		wantMatch bool
 		wantAs    ErrorCode
 	}{{
-		name:      "ErrBadInputSize == ErrBadInputSize",
-		err:       ErrBadInputSize,
-		target:    ErrBadInputSize,
+		name:      "ErrInvalidHashLen == ErrInvalidHashLen",
+		err:       ErrInvalidHashLen,
+		target:    ErrInvalidHashLen,
 		wantMatch: true,
-		wantAs:    ErrBadInputSize,
+		wantAs:    ErrInvalidHashLen,
 	}, {
-		name:      "Error.ErrBadInputSize == ErrBadInputSize",
-		err:       signatureError(ErrBadInputSize, ""),
-		target:    ErrBadInputSize,
+		name:      "Error.ErrInvalidHashLen == ErrInvalidHashLen",
+		err:       signatureError(ErrInvalidHashLen, ""),
+		target:    ErrInvalidHashLen,
 		wantMatch: true,
-		wantAs:    ErrBadInputSize,
+		wantAs:    ErrInvalidHashLen,
 	}, {
-		name:      "ErrBadInputSize == Error.ErrBadInputSize",
-		err:       ErrBadInputSize,
-		target:    signatureError(ErrBadInputSize, ""),
+		name:      "ErrInvalidHashLen == Error.ErrInvalidHashLen",
+		err:       ErrInvalidHashLen,
+		target:    signatureError(ErrInvalidHashLen, ""),
 		wantMatch: true,
-		wantAs:    ErrBadInputSize,
+		wantAs:    ErrInvalidHashLen,
 	}, {
-		name:      "Error.ErrBadInputSize == Error.ErrBadInputSize",
-		err:       signatureError(ErrBadInputSize, ""),
-		target:    signatureError(ErrBadInputSize, ""),
+		name:      "Error.ErrInvalidHashLen == Error.ErrInvalidHashLen",
+		err:       signatureError(ErrInvalidHashLen, ""),
+		target:    signatureError(ErrInvalidHashLen, ""),
 		wantMatch: true,
-		wantAs:    ErrBadInputSize,
+		wantAs:    ErrInvalidHashLen,
 	}, {
-		name:      "ErrInputValue != ErrBadInputSize",
-		err:       ErrInputValue,
-		target:    ErrBadInputSize,
+		name:      "ErrPrivateKeyIsZero != ErrInvalidHashLen",
+		err:       ErrPrivateKeyIsZero,
+		target:    ErrInvalidHashLen,
 		wantMatch: false,
-		wantAs:    ErrInputValue,
+		wantAs:    ErrPrivateKeyIsZero,
 	}, {
-		name:      "Error.ErrInputValue != ErrBadInputSize",
-		err:       signatureError(ErrInputValue, ""),
-		target:    ErrBadInputSize,
+		name:      "Error.ErrPrivateKeyIsZero != ErrInvalidHashLen",
+		err:       signatureError(ErrPrivateKeyIsZero, ""),
+		target:    ErrInvalidHashLen,
 		wantMatch: false,
-		wantAs:    ErrInputValue,
+		wantAs:    ErrPrivateKeyIsZero,
 	}, {
-		name:      "ErrInputValue != Error.ErrBadInputSize",
-		err:       ErrInputValue,
-		target:    signatureError(ErrBadInputSize, ""),
+		name:      "ErrPrivateKeyIsZero != Error.ErrInvalidHashLen",
+		err:       ErrPrivateKeyIsZero,
+		target:    signatureError(ErrInvalidHashLen, ""),
 		wantMatch: false,
-		wantAs:    ErrInputValue,
+		wantAs:    ErrPrivateKeyIsZero,
 	}, {
-		name:      "Error.ErrInputValue != Error.ErrBadInputSize",
-		err:       signatureError(ErrInputValue, ""),
-		target:    signatureError(ErrBadInputSize, ""),
+		name:      "Error.ErrPrivateKeyIsZero != Error.ErrInvalidHashLen",
+		err:       signatureError(ErrPrivateKeyIsZero, ""),
+		target:    signatureError(ErrInvalidHashLen, ""),
 		wantMatch: false,
-		wantAs:    ErrInputValue,
+		wantAs:    ErrPrivateKeyIsZero,
 	}}
 
 	for _, test := range tests {

dcrec/secp256k1/schnorr/signature.go

@@ -142,7 +142,7 @@ func schnorrVerify(sig *Signature, hash []byte, pubKey *secp256k1.PublicKey) err
 	if len(hash) != scalarSize {
 		str := fmt.Sprintf("wrong size for message (got %v, want %v)",
 			len(hash), scalarSize)
-		return signatureError(ErrBadInputSize, str)
+		return signatureError(ErrInvalidHashLen, str)
 	}
 
 	// Step 2.
@@ -151,7 +151,7 @@ func schnorrVerify(sig *Signature, hash []byte, pubKey *secp256k1.PublicKey) err
 	curve := secp256k1.S256()
 	if !curve.IsOnCurve(pubKey.X(), pubKey.Y()) {
 		str := "pubkey point is not on curve"
-		return signatureError(ErrPointNotOnCurve, str)
+		return signatureError(ErrPubKeyNotOnCurve, str)
 	}
 
 	// Step 3.
@@ -199,7 +199,7 @@ func schnorrVerify(sig *Signature, hash []byte, pubKey *secp256k1.PublicKey) err
 	// Fail if R is the point at infinity
 	if (R.X.IsZero() && R.Y.IsZero()) || R.Z.IsZero() {
 		str := "calculated R point is the point at infinity"
-		return signatureError(ErrBadSigRNotOnCurve, str)
+		return signatureError(ErrSigRNotOnCurve, str)
 	}
 
 	// Step 9.
@@ -210,7 +210,7 @@ func schnorrVerify(sig *Signature, hash []byte, pubKey *secp256k1.PublicKey) err
 	R.ToAffine()
 	if R.Y.IsOdd() {
 		str := "calculated R y-value is odd"
-		return signatureError(ErrBadSigRYValue, str)
+		return signatureError(ErrSigRYIsOdd, str)
 	}
 
 	// Step 10.
@@ -366,7 +366,7 @@ func Sign(privKey *secp256k1.PrivateKey, hash []byte) (*Signature, error) {
 	if len(hash) != scalarSize {
 		str := fmt.Sprintf("wrong size for message hash (got %v, want %v)",
 			len(hash), scalarSize)
-		return nil, signatureError(ErrBadInputSize, str)
+		return nil, signatureError(ErrInvalidHashLen, str)
 	}
 
 	// Step 2.
@@ -375,7 +375,7 @@ func Sign(privKey *secp256k1.PrivateKey, hash []byte) (*Signature, error) {
 	privKeyScalar := &privKey.Key
 	if privKeyScalar.IsZero() {
 		str := "private key is zero"
-		return nil, signatureError(ErrInputValue, str)
+		return nil, signatureError(ErrPrivateKeyIsZero, str)
 	}
 
 	var privKeyBytes [scalarSize]byte

dcrec/secp256k1/schnorr/signature_test.go

@@ -412,7 +412,7 @@ func TestVerifyErrors(t *testing.T) {
 		hash: "c301ba9de5d6053caad9f5eb46523f007702add2c62fa39de03146a36b8026b700",
 		pubX: "79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
 		pubY: "483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8",
-		err:  ErrBadInputSize,
+		err:  ErrInvalidHashLen,
 	}, {
 		// Signature created from private key 0x01, blake256(0x40) and removing
 		// the leading zero byte.  It is otherwise valid.
@@ -422,7 +422,7 @@ func TestVerifyErrors(t *testing.T) {
 		hash: "0e0f08e2ee912478b77004ec62845b5e01418f03837b76cbdc8b1fb0480322",
 		pubX: "79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
 		pubY: "483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8",
-		err:  ErrBadInputSize,
+		err:  ErrInvalidHashLen,
 	}, {
 		// Signature created from private key 0x01, blake256(0x01020304) over
 		// the secp256r1 curve (note the r1 instead of k1).
@@ -432,7 +432,7 @@ func TestVerifyErrors(t *testing.T) {
 		hash: "c301ba9de5d6053caad9f5eb46523f007702add2c62fa39de03146a36b8026b7",
 		pubX: "6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296",
 		pubY: "4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5",
-		err:  ErrPointNotOnCurve,
+		err:  ErrPubKeyNotOnCurve,
 	}, {
 		// Signature invented since finding a signature with an r value that is
 		// exactly the field prime prior to the modular reduction is not
@@ -490,7 +490,7 @@ func TestVerifyErrors(t *testing.T) {
 		hash: "c301ba9de5d6053caad9f5eb46523f007702add2c62fa39de03146a36b8026b7",
 		pubX: "79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
 		pubY: "483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8",
-		err:  ErrBadSigRNotOnCurve,
+		err:  ErrSigRNotOnCurve,
 	}, {
 		// Signature created from private key 0x01, blake256(0x01020304050607).
 		// It is otherwise valid.
@@ -500,7 +500,7 @@ func TestVerifyErrors(t *testing.T) {
 		hash: "ccf8c53a7631aad469d412963d495c729ff219dd2ae9a0c4de4bd1b4c777d49c",
 		pubX: "79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
 		pubY: "483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8",
-		err:  ErrBadSigRYValue,
+		err:  ErrSigRYIsOdd,
 	}, {
 		// Signature created from private key 0x01, blake256(0x01020304).  Thus,
 		// it is valid for that message.  Attempting to verify wrong message