diff --git a/sign/pdfsignature.go b/sign/pdfsignature.go
index 134b5fd..4998119 100644
--- a/sign/pdfsignature.go
+++ b/sign/pdfsignature.go
@@ -8,7 +8,7 @@ import (
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"strconv"
 
@@ -269,7 +269,7 @@ func (context *SignContext) GetTSA(sign_content []byte) (timestamp_response []by
 	if err != nil || (code < 200 || code > 299) {
 		if err == nil {
 			defer resp.Body.Close()
-			body, _ := ioutil.ReadAll(resp.Body)
+			body, _ := io.ReadAll(resp.Body)
 			return nil, errors.New("non success response (" + strconv.Itoa(code) + "): " + string(body))
 		}
 
@@ -277,7 +277,7 @@ func (context *SignContext) GetTSA(sign_content []byte) (timestamp_response []by
 	}
 
 	defer resp.Body.Close()
-	timestamp_response_body, err := ioutil.ReadAll(resp.Body)
+	timestamp_response_body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read response: %w", err)
 	}
diff --git a/sign/revocation.go b/sign/revocation.go
index f6d9553..52caa37 100644
--- a/sign/revocation.go
+++ b/sign/revocation.go
@@ -4,7 +4,7 @@ import (
 	"crypto/x509"
 	"encoding/base64"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"strings"
 
@@ -27,7 +27,7 @@ func embedOCSPRevocationStatus(cert, issuer *x509.Certificate, i *revocation.Inf
 		return err
 	}
 	defer resp.Body.Close()
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return err
 	}
@@ -49,7 +49,7 @@ func embedCRLRevocationStatus(cert, issuer *x509.Certificate, i *revocation.Info
 		return err
 	}
 	defer resp.Body.Close()
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return err
 	}
diff --git a/sign/sign_test.go b/sign/sign_test.go
index 8b3fce0..ec02fc7 100644
--- a/sign/sign_test.go
+++ b/sign/sign_test.go
@@ -5,7 +5,7 @@ import (
 	"crypto/x509"
 	"encoding/base64"
 	"encoding/pem"
-	"io/ioutil"
+	"io"
 	"os"
 	"path/filepath"
 	"testing"
@@ -57,7 +57,7 @@ xLqE5nXC5oIUTbuSK+b/poFFrtjKUFgxf0a/W2Ktsw==
 const staticPDFFile = `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`
 
 func TestReaderCanReadPDF(t *testing.T) {
-	files, err := ioutil.ReadDir("../testfiles")
+	files, err := os.ReadDir("../testfiles")
 	if err != nil {
 		t.Errorf("%s", err.Error())
 		return
@@ -103,7 +103,7 @@ func TestSignPDF(t *testing.T) {
 	_ = os.RemoveAll("../testfiles/failed/")
 	_ = os.MkdirAll("../testfiles/failed/", 0777)
 
-	files, err := ioutil.ReadDir("../testfiles")
+	files, err := os.ReadDir("../testfiles")
 	if err != nil {
 		t.Errorf("%s", err.Error())
 		return
@@ -167,7 +167,7 @@ func TestSignPDF(t *testing.T) {
 				return
 			}
 
-			outputFile, err := ioutil.TempFile("", "pdfsign_test_"+f.Name())
+			outputFile, err := os.CreateTemp("", "pdfsign_test_"+f.Name())
 			if err != nil {
 				t.Errorf("%s", err.Error())
 				return
@@ -242,7 +242,7 @@ func TestSignPDFFile(t *testing.T) {
 		return
 	}
 
-	tmpfile, err := ioutil.TempFile("", "pdfsign_test")
+	tmpfile, err := os.CreateTemp("", "pdfsign_test")
 	if err != nil {
 		t.Errorf("%s", err.Error())
 		return
@@ -333,7 +333,7 @@ func BenchmarkSignPDF(b *testing.B) {
 			return
 		}
 
-		err = Sign(input_file, ioutil.Discard, rdr, size, SignData{
+		err = Sign(input_file, io.Discard, rdr, size, SignData{
 			Signature: SignDataSignature{
 				Info: SignDataSignatureInfo{
 					Name:        "John Doe",
diff --git a/verify/verify.go b/verify/verify.go
index 73b395c..5a57a83 100644
--- a/verify/verify.go
+++ b/verify/verify.go
@@ -7,7 +7,6 @@ import (
 	"encoding/asn1"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"reflect"
 	"time"
@@ -146,7 +145,7 @@ func Reader(file io.ReaderAt, size int64) (apiResp *Response, err error) {
 			// This content will be hashed with the corresponding algorithm to
 			// verify the signature.
 
-			content, err := ioutil.ReadAll(io.NewSectionReader(file, v.Key("ByteRange").Index(i-1).Int64(), v.Key("ByteRange").Index(i).Int64()))
+			content, err := io.ReadAll(io.NewSectionReader(file, v.Key("ByteRange").Index(i-1).Int64(), v.Key("ByteRange").Index(i).Int64()))
 			if err != nil {
 				apiResp.Error = fmt.Sprintln("Failed to get ByteRange:", i, err)
 			}