diff --git a/encoding.go b/encoding.go
index b3062ab8..dea533e8 100644
--- a/encoding.go
+++ b/encoding.go
@@ -23,13 +23,12 @@ import (
 	"encoding/binary"
 	"io"
 	"math/big"
-	"regexp"
+	"strings"
+	"unicode"
 
 	"github.com/square/go-jose/v3/json"
 )
 
-var stripWhitespaceRegex = regexp.MustCompile(`\s`)
-
 // Helper function to serialize known-good objects.
 // Precondition: value is not a nil pointer.
 func mustSerializeJSON(value interface{}) []byte {
@@ -56,7 +55,16 @@ func mustSerializeJSON(value interface{}) []byte {
 
 // Strip all newlines and whitespace
 func stripWhitespace(data string) string {
-	return stripWhitespaceRegex.ReplaceAllString(data, "")
+	buf := strings.Builder{}
+	buf.Grow(len(data))
+
+	for _, r := range data {
+		if !unicode.IsSpace(r) {
+			buf.WriteRune(r)
+		}
+	}
+
+	return buf.String()
 }
 
 // Perform compression based on algorithm
diff --git a/jws.go b/jws.go
index 6bb310e6..a05c56bd 100644
--- a/jws.go
+++ b/jws.go
@@ -102,14 +102,14 @@ func (sig Signature) mergedHeaders() rawHeader {
 }
 
 // Compute data to be signed
-func (obj JSONWebSignature) computeAuthData(payload []byte, signature *Signature) []byte {
+func (obj JSONWebSignature) computeAuthData(payload []byte, signature *Signature) ([]byte, error) {
 	var authData bytes.Buffer
 
 	protectedHeader := new(rawHeader)
 
 	if signature.original != nil && signature.original.Protected != nil {
 		if err := json.Unmarshal(signature.original.Protected.bytes(), protectedHeader); err != nil {
-			panic(err)
+			return nil, err
 		}
 		authData.WriteString(signature.original.Protected.base64())
 	} else if signature.protected != nil {
@@ -134,7 +134,7 @@ func (obj JSONWebSignature) computeAuthData(payload []byte, signature *Signature
 		authData.Write(payload)
 	}
 
-	return authData.Bytes()
+	return authData.Bytes(), nil
 }
 
 // parseSignedFull parses a message in full format.
diff --git a/jws_test.go b/jws_test.go
index 64b0b7c0..2ed51973 100644
--- a/jws_test.go
+++ b/jws_test.go
@@ -18,8 +18,11 @@ package jose
 
 import (
 	"crypto/x509"
+	"encoding/base64"
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 const trustedCA = `
@@ -649,3 +652,39 @@ func TestDetachedCompactSerialization(t *testing.T) {
 		t.Fatalf("got '%s', expected '%s'", ser, msg)
 	}
 }
+
+func TestJWSComputeAuthDataBase64(t *testing.T) {
+	jws := JSONWebSignature{}
+
+	_, err := jws.computeAuthData([]byte{0x01}, &Signature{
+		original: &rawSignatureInfo{
+			Protected: newBuffer([]byte("{!invalid-json}")),
+		},
+	})
+	// Invalid header, should return error
+	assert.NotNil(t, err)
+
+	payload := []byte{0x01}
+	encodedPayload := base64.RawURLEncoding.EncodeToString(payload)
+
+	b64TrueHeader := newBuffer([]byte(`{"alg":"RSA-OAEP","enc":"A256GCM","b64":true}`))
+	b64FalseHeader := newBuffer([]byte(`{"alg":"RSA-OAEP","enc":"A256GCM","b64":false}`))
+
+	data, err := jws.computeAuthData(payload, &Signature{
+		original: &rawSignatureInfo{
+			Protected: b64TrueHeader,
+		},
+	})
+	assert.Nil(t, err)
+	// Payload should be b64 encoded
+	assert.Len(t, data, len(b64TrueHeader.base64())+len(encodedPayload)+1)
+
+	data, err = jws.computeAuthData(payload, &Signature{
+		original: &rawSignatureInfo{
+			Protected: b64FalseHeader,
+		},
+	})
+	assert.Nil(t, err)
+	// Payload should *not* be b64 encoded
+	assert.Len(t, data, len(b64FalseHeader.base64())+len(payload)+1)
+}
diff --git a/jwt/validation.go b/jwt/validation.go
index 045d5dfb..6f3ff4e8 100644
--- a/jwt/validation.go
+++ b/jwt/validation.go
@@ -35,7 +35,7 @@ type Expected struct {
 	Audience Audience
 	// ID matches the "jti" claim exactly.
 	ID string
-	// Time matches the "exp" and "nbf" claims with leeway.
+	// Time matches the "exp", "nbf" and "iat" claims with leeway.
 	Time time.Time
 }
 
diff --git a/signing.go b/signing.go
index 0a631bb9..cd086053 100644
--- a/signing.go
+++ b/signing.go
@@ -370,7 +370,11 @@ func (obj JSONWebSignature) DetachedVerify(payload []byte, verificationKey inter
 		}
 	}
 
-	input := obj.computeAuthData(payload, &signature)
+	input, err := obj.computeAuthData(payload, &signature)
+	if err != nil {
+		return ErrCryptoFailure
+	}
+
 	alg := headers.getSignatureAlgorithm()
 	err = verifier.verifyPayload(input, signature.Signature, alg)
 	if err == nil {
@@ -421,7 +425,11 @@ outer:
 			}
 		}
 
-		input := obj.computeAuthData(payload, &signature)
+		input, err := obj.computeAuthData(payload, &signature)
+		if err != nil {
+			continue
+		}
+
 		alg := headers.getSignatureAlgorithm()
 		err = verifier.verifyPayload(input, signature.Signature, alg)
 		if err == nil {
diff --git a/signing_test.go b/signing_test.go
index c6c20791..a73488b6 100644
--- a/signing_test.go
+++ b/signing_test.go
@@ -583,3 +583,14 @@ func TestSignerB64(t *testing.T) {
 		t.Errorf("Input/output do not match, got '%s', expected '%s'", output, input)
 	}
 }
+
+func BenchmarkParseSigned(b *testing.B) {
+	msg := `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c`
+
+	for i := 0; i < b.N; i++ {
+		_, err := ParseSigned(msg)
+		if err != nil {
+			b.Errorf("Error on parse: %s", err)
+		}
+	}
+}