优化结构

internal/integration/payment/apple_jws.go

@@ -1,12 +1,17 @@
 package payment
 
 import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/sha256"
 	"crypto/x509"
 	"encoding/asn1"
 	"encoding/base64"
+	"encoding/hex"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math/big"
 	"strings"
 	"time"
 )
@@ -20,12 +25,16 @@ const (
 var (
 	appleJWSLeafExtensionOID         = asn1.ObjectIdentifier{1, 2, 840, 113635, 100, 6, 11, 1}
 	appleJWSIntermediateExtensionOID = asn1.ObjectIdentifier{1, 2, 840, 113635, 100, 6, 2, 1}
+	appleTrustedRootFingerprints     = map[string]struct{}{
+		"63343abfb89a6a03ebb57e9b3f5fa7be7c4f5c756f3017b3a8c488c3653e9179": {},
+	}
 )
 
-// validateAppleJWSChain binds the leaf certificate used by GoPay for JWS
-// signature verification to the intermediate and root certificates that
-// GoPay validates against its embedded Apple trust anchor.
 func validateAppleJWSChain(signedPayload string) error {
+	return validateAppleJWSChainWithRoots(signedPayload, appleTrustedRootFingerprints)
+}
+
+func validateAppleJWSChainWithRoots(signedPayload string, trustedRoots map[string]struct{}) error {
 	headerSegment, payloadSegment, signatureSegment, err := splitAppleJWS(signedPayload)
 	if err != nil {
 		return err
@@ -73,6 +82,10 @@ func validateAppleJWSChain(signedPayload string) error {
 		}
 		certificates = append(certificates, certificate)
 	}
+	rootFingerprint := sha256.Sum256(certificates[2].Raw)
+	if _, trusted := trustedRoots[hex.EncodeToString(rootFingerprint[:])]; !trusted {
+		return errors.New("Apple JWS 根证书不受信任")
+	}
 	if err = certificates[0].CheckSignatureFrom(certificates[1]); err != nil {
 		return fmt.Errorf("Apple JWS 叶子证书不属于声明的证书链: %w", err)
 	}
@@ -101,19 +114,20 @@ func validateAppleJWSChain(signedPayload string) error {
 		return errors.New("Apple JWS 中间证书缺少 Apple 签名扩展")
 	}
 
-	if hasVerificationTime {
-		roots := x509.NewCertPool()
-		roots.AddCert(certificates[2])
-		intermediates := x509.NewCertPool()
-		intermediates.AddCert(certificates[1])
-		if _, err = certificates[0].Verify(x509.VerifyOptions{
-			Roots:         roots,
-			Intermediates: intermediates,
-			KeyUsages:     []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
-			CurrentTime:   verificationTime,
-		}); err != nil {
-			return fmt.Errorf("验证 Apple JWS 证书链: %w", err)
-		}
+	if !hasVerificationTime {
+		verificationTime = time.Now()
+	}
+	roots := x509.NewCertPool()
+	roots.AddCert(certificates[2])
+	intermediates := x509.NewCertPool()
+	intermediates.AddCert(certificates[1])
+	if _, err = certificates[0].Verify(x509.VerifyOptions{
+		Roots:         roots,
+		Intermediates: intermediates,
+		KeyUsages:     []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
+		CurrentTime:   verificationTime,
+	}); err != nil {
+		return fmt.Errorf("验证 Apple JWS 证书链: %w", err)
 	}
 	if certificates[0].IsCA {
 		return errors.New("Apple JWS 叶子证书不能是 CA")
@@ -121,6 +135,18 @@ func validateAppleJWSChain(signedPayload string) error {
 	if certificates[0].KeyUsage != 0 && certificates[0].KeyUsage&x509.KeyUsageDigitalSignature == 0 {
 		return errors.New("Apple JWS 叶子证书不允许数字签名")
 	}
+	publicKey, ok := certificates[0].PublicKey.(*ecdsa.PublicKey)
+	if !ok || publicKey.Curve != elliptic.P256() {
+		return errors.New("Apple JWS 叶子证书不是 P-256 ECDSA 公钥")
+	}
+	signature, err := base64.RawURLEncoding.DecodeString(signatureSegment)
+	if err != nil || len(signature) != 64 {
+		return errors.New("Apple JWS ES256 签名格式无效")
+	}
+	digest := sha256.Sum256([]byte(headerSegment + "." + payloadSegment))
+	if !ecdsa.Verify(publicKey, digest[:], new(big.Int).SetBytes(signature[:32]), new(big.Int).SetBytes(signature[32:])) {
+		return errors.New("Apple JWS 签名校验失败")
+	}
 	return nil
 }