From f6c92c5e2d87ab1334648b0d1293771de7aae4a5 Mon Sep 17 00:00:00 2001
From: Rutger Broekhoff
Date: Sat, 30 Dec 2023 14:00:34 +0100
Subject: Implement git-lfs-authenticate

---
 vendor/github.com/golang-jwt/jwt/v5/ecdsa.go | 134 +++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 vendor/github.com/golang-jwt/jwt/v5/ecdsa.go

(limited to 'vendor/github.com/golang-jwt/jwt/v5/ecdsa.go')

diff --git a/vendor/github.com/golang-jwt/jwt/v5/ecdsa.go b/vendor/github.com/golang-jwt/jwt/v5/ecdsa.go
new file mode 100644
index 0000000..ca85659
--- /dev/null
+++ b/vendor/github.com/golang-jwt/jwt/v5/ecdsa.go
@@ -0,0 +1,134 @@
+package jwt
+
+import (
+	"crypto"
+	"crypto/ecdsa"
+	"crypto/rand"
+	"errors"
+	"math/big"
+)
+
+var (
+	// Sadly this is missing from crypto/ecdsa compared to crypto/rsa
+	ErrECDSAVerification = errors.New("crypto/ecdsa: verification error")
+)
+
+// SigningMethodECDSA implements the ECDSA family of signing methods.
+// Expects *ecdsa.PrivateKey for signing and *ecdsa.PublicKey for verification
+type SigningMethodECDSA struct {
+	Name      string
+	Hash      crypto.Hash
+	KeySize   int
+	CurveBits int
+}
+
+// Specific instances for EC256 and company
+var (
+	SigningMethodES256 *SigningMethodECDSA
+	SigningMethodES384 *SigningMethodECDSA
+	SigningMethodES512 *SigningMethodECDSA
+)
+
+func init() {
+	// ES256
+	SigningMethodES256 = &SigningMethodECDSA{"ES256", crypto.SHA256, 32, 256}
+	RegisterSigningMethod(SigningMethodES256.Alg(), func() SigningMethod {
+		return SigningMethodES256
+	})
+
+	// ES384
+	SigningMethodES384 = &SigningMethodECDSA{"ES384", crypto.SHA384, 48, 384}
+	RegisterSigningMethod(SigningMethodES384.Alg(), func() SigningMethod {
+		return SigningMethodES384
+	})
+
+	// ES512
+	SigningMethodES512 = &SigningMethodECDSA{"ES512", crypto.SHA512, 66, 521}
+	RegisterSigningMethod(SigningMethodES512.Alg(), func() SigningMethod {
+		return SigningMethodES512
+	})
+}
+
+func (m *SigningMethodECDSA) Alg() string {
+	return m.Name
+}
+
+// Verify implements token verification for the SigningMethod.
+// For this verify method, key must be an ecdsa.PublicKey struct
+func (m *SigningMethodECDSA) Verify(signingString string, sig []byte, key interface{}) error {
+	// Get the key
+	var ecdsaKey *ecdsa.PublicKey
+	switch k := key.(type) {
+	case *ecdsa.PublicKey:
+		ecdsaKey = k
+	default:
+		return newError("ECDSA verify expects *ecsda.PublicKey", ErrInvalidKeyType)
+	}
+
+	if len(sig) != 2*m.KeySize {
+		return ErrECDSAVerification
+	}
+
+	r := big.NewInt(0).SetBytes(sig[:m.KeySize])
+	s := big.NewInt(0).SetBytes(sig[m.KeySize:])
+
+	// Create hasher
+	if !m.Hash.Available() {
+		return ErrHashUnavailable
+	}
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Verify the signature
+	if verifystatus := ecdsa.Verify(ecdsaKey, hasher.Sum(nil), r, s); verifystatus {
+		return nil
+	}
+
+	return ErrECDSAVerification
+}
+
+// Sign implements token signing for the SigningMethod.
+// For this signing method, key must be an ecdsa.PrivateKey struct
+func (m *SigningMethodECDSA) Sign(signingString string, key interface{}) ([]byte, error) {
+	// Get the key
+	var ecdsaKey *ecdsa.PrivateKey
+	switch k := key.(type) {
+	case *ecdsa.PrivateKey:
+		ecdsaKey = k
+	default:
+		return nil, newError("ECDSA sign expects *ecsda.PrivateKey", ErrInvalidKeyType)
+	}
+
+	// Create the hasher
+	if !m.Hash.Available() {
+		return nil, ErrHashUnavailable
+	}
+
+	hasher := m.Hash.New()
+	hasher.Write([]byte(signingString))
+
+	// Sign the string and return r, s
+	if r, s, err := ecdsa.Sign(rand.Reader, ecdsaKey, hasher.Sum(nil)); err == nil {
+		curveBits := ecdsaKey.Curve.Params().BitSize
+
+		if m.CurveBits != curveBits {
+			return nil, ErrInvalidKey
+		}
+
+		keyBytes := curveBits / 8
+		if curveBits%8 > 0 {
+			keyBytes += 1
+		}
+
+		// We serialize the outputs (r and s) into big-endian byte arrays
+		// padded with zeros on the left to make sure the sizes work out.
+		// Output must be 2*keyBytes long.
+		out := make([]byte, 2*keyBytes)
+		r.FillBytes(out[0:keyBytes]) // r is assigned to the first half of output.
+		s.FillBytes(out[keyBytes:])  // s is assigned to the second half of output.
+
+		return out, nil
+	} else {
+		return nil, err
+	}
+}
-- 
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