Update dependencies (#975)

vendor/golang.org/x/crypto/acme/jws.go

@@ -11,31 +11,60 @@ import (
 	"crypto/rsa"
 	"crypto/sha256"
 	_ "crypto/sha512" // need for EC keys
+	"encoding/asn1"
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"math/big"
 )
 
+// keyID is the account identity provided by a CA during registration.
+type keyID string
+
+// noKeyID indicates that jwsEncodeJSON should compute and use JWK instead of a KID.
+// See jwsEncodeJSON for details.
+const noKeyID = keyID("")
+
+// noPayload indicates jwsEncodeJSON will encode zero-length octet string
+// in a JWS request. This is called POST-as-GET in RFC 8555 and is used to make
+// authenticated GET requests via POSTing with an empty payload.
+// See https://tools.ietf.org/html/rfc8555#section-6.3 for more details.
+const noPayload = ""
+
 // jwsEncodeJSON signs claimset using provided key and a nonce.
-// The result is serialized in JSON format.
+// The result is serialized in JSON format containing either kid or jwk
+// fields based on the provided keyID value.
+//
+// If kid is non-empty, its quoted value is inserted in the protected head
+// as "kid" field value. Otherwise, JWK is computed using jwkEncode and inserted
+// as "jwk" field value. The "jwk" and "kid" fields are mutually exclusive.
+//
 // See https://tools.ietf.org/html/rfc7515#section-7.
-func jwsEncodeJSON(claimset interface{}, key crypto.Signer, nonce string) ([]byte, error) {
-	jwk, err := jwkEncode(key.Public())
-	if err != nil {
-		return nil, err
-	}
+func jwsEncodeJSON(claimset interface{}, key crypto.Signer, kid keyID, nonce, url string) ([]byte, error) {
 	alg, sha := jwsHasher(key.Public())
 	if alg == "" || !sha.Available() {
 		return nil, ErrUnsupportedKey
 	}
-	phead := fmt.Sprintf(`{"alg":%q,"jwk":%s,"nonce":%q}`, alg, jwk, nonce)
-	phead = base64.RawURLEncoding.EncodeToString([]byte(phead))
-	cs, err := json.Marshal(claimset)
-	if err != nil {
-		return nil, err
+	var phead string
+	switch kid {
+	case noKeyID:
+		jwk, err := jwkEncode(key.Public())
+		if err != nil {
+			return nil, err
+		}
+		phead = fmt.Sprintf(`{"alg":%q,"jwk":%s,"nonce":%q,"url":%q}`, alg, jwk, nonce, url)
+	default:
+		phead = fmt.Sprintf(`{"alg":%q,"kid":%q,"nonce":%q,"url":%q}`, alg, kid, nonce, url)
+	}
+	phead = base64.RawURLEncoding.EncodeToString([]byte(phead))
+	var payload string
+	if claimset != noPayload {
+		cs, err := json.Marshal(claimset)
+		if err != nil {
+			return nil, err
+		}
+		payload = base64.RawURLEncoding.EncodeToString(cs)
 	}
-	payload := base64.RawURLEncoding.EncodeToString(cs)
 	hash := sha.New()
 	hash.Write([]byte(phead + "." + payload))
 	sig, err := jwsSign(key, sha, hash.Sum(nil))
@@ -98,21 +127,23 @@ func jwkEncode(pub crypto.PublicKey) (string, error) {
 
 // jwsSign signs the digest using the given key.
 // The hash is unused for ECDSA keys.
-//
-// Note: non-stdlib crypto.Signer implementations are expected to return
-// the signature in the format as specified in RFC7518.
-// See https://tools.ietf.org/html/rfc7518 for more details.
 func jwsSign(key crypto.Signer, hash crypto.Hash, digest []byte) ([]byte, error) {
-	if key, ok := key.(*ecdsa.PrivateKey); ok {
-		// The key.Sign method of ecdsa returns ASN1-encoded signature.
-		// So, we use the package Sign function instead
-		// to get R and S values directly and format the result accordingly.
-		r, s, err := ecdsa.Sign(rand.Reader, key, digest)
+	switch pub := key.Public().(type) {
+	case *rsa.PublicKey:
+		return key.Sign(rand.Reader, digest, hash)
+	case *ecdsa.PublicKey:
+		sigASN1, err := key.Sign(rand.Reader, digest, hash)
 		if err != nil {
 			return nil, err
 		}
-		rb, sb := r.Bytes(), s.Bytes()
-		size := key.Params().BitSize / 8
+
+		var rs struct{ R, S *big.Int }
+		if _, err := asn1.Unmarshal(sigASN1, &rs); err != nil {
+			return nil, err
+		}
+
+		rb, sb := rs.R.Bytes(), rs.S.Bytes()
+		size := pub.Params().BitSize / 8
 		if size%8 > 0 {
 			size++
 		}
@@ -121,7 +152,7 @@ func jwsSign(key crypto.Signer, hash crypto.Hash, digest []byte) ([]byte, error)
 		copy(sig[size*2-len(sb):], sb)
 		return sig, nil
 	}
-	return key.Sign(rand.Reader, digest, hash)
+	return nil, ErrUnsupportedKey
 }
 
 // jwsHasher indicates suitable JWS algorithm name and a hash function