diff --git a/saml_test.go b/saml_test.go
index d59a5e1..6141435 100644
--- a/saml_test.go
+++ b/saml_test.go
@@ -25,8 +25,8 @@ import (
 	"encoding/pem"
 	"encoding/xml"
 	"fmt"
-	"io/ioutil"
 	"log"
+	"os"
 	"testing"
 
 	"github.com/beevik/etree"
@@ -49,7 +49,7 @@ func init() {
 }
 
 func TestDecode(t *testing.T) {
-	f, err := ioutil.ReadFile("./testdata/saml.post")
+	f, err := os.ReadFile("./testdata/saml.post")
 	if err != nil {
 		t.Fatalf("could not open test file: %v\n", err)
 	}
@@ -65,7 +65,7 @@ func TestDecode(t *testing.T) {
 
 	ea := response.EncryptedAssertions[0]
 
-	k, err := ea.EncryptedKey.DecryptSymmetricKey(&cert)
+	k, err := ea.EncryptedKey.DecryptSymmetricKey(&cert, ea.EncryptionMethod.Algorithm)
 	if err != nil {
 		t.Fatalf("could not get symmetric key: %v\n", err)
 	}
@@ -79,7 +79,7 @@ func TestDecode(t *testing.T) {
 		t.Fatalf("error decrypting saml data: %v\n", err)
 	}
 
-	f2, err := ioutil.ReadFile("./testdata/saml.xml")
+	f2, err := os.ReadFile("./testdata/saml.xml")
 	if err != nil {
 		t.Fatalf("could not read expected output")
 	}
diff --git a/types/encrypted_assertion.go b/types/encrypted_assertion.go
index 150e505..02cdd17 100644
--- a/types/encrypted_assertion.go
+++ b/types/encrypted_assertion.go
@@ -44,7 +44,7 @@ func (ea *EncryptedAssertion) DecryptBytes(cert *tls.Certificate) ([]byte, error
 		// https://www.w3.org/TR/2002/REC-xmlenc-core-20021210/Overview.html#sec-Extensions-to-KeyInfo
 		ek = &ea.DetEncryptedKey
 	}
-	k, err := ek.DecryptSymmetricKey(cert)
+	k, err := ek.DecryptSymmetricKey(cert, ea.EncryptionMethod.Algorithm)
 	if err != nil {
 		return nil, fmt.Errorf("cannot decrypt, error retrieving private key: %s", err)
 	}
diff --git a/types/encrypted_key.go b/types/encrypted_key.go
index 82db74b..12ffbae 100644
--- a/types/encrypted_key.go
+++ b/types/encrypted_key.go
@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"crypto/aes"
 	"crypto/cipher"
+	"crypto/des"
 	"crypto/rand"
 	"crypto/rsa"
 	"crypto/sha1"
@@ -31,8 +32,8 @@ import (
 	"strings"
 )
 
-//EncryptedKey contains the decryption key data from the saml2 core and xmlenc
-//standards.
+// EncryptedKey contains the decryption key data from the saml2 core and xmlenc
+// standards.
 type EncryptedKey struct {
 	// EncryptionMethod string `xml:"EncryptionMethod>Algorithm"`
 	X509Data         string `xml:"KeyInfo>X509Data>X509Certificate"`
@@ -40,7 +41,7 @@ type EncryptedKey struct {
 	EncryptionMethod EncryptionMethod
 }
 
-//EncryptionMethod specifies the type of encryption that was used.
+// EncryptionMethod specifies the type of encryption that was used.
 type EncryptionMethod struct {
 	Algorithm string `xml:",attr,omitempty"`
 	//Digest method is present for algorithms like RSA-OAEP.
@@ -51,19 +52,19 @@ type EncryptionMethod struct {
 	DigestMethod *DigestMethod `xml:",omitempty"`
 }
 
-//DigestMethod is a digest type specification
+// DigestMethod is a digest type specification
 type DigestMethod struct {
 	Algorithm string `xml:",attr,omitempty"`
 }
 
-//Well-known public-key encryption methods
+// Well-known public-key encryption methods
 const (
 	MethodRSAOAEP  = "http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p"
 	MethodRSAOAEP2 = "http://www.w3.org/2009/xmlenc11#rsa-oaep"
 	MethodRSAv1_5  = "http://www.w3.org/2001/04/xmlenc#rsa-1_5"
 )
 
-//Well-known private key encryption methods
+// Well-known private key encryption methods
 const (
 	MethodAES128GCM    = "http://www.w3.org/2009/xmlenc11#aes128-gcm"
 	MethodAES192GCM    = "http://www.w3.org/2009/xmlenc11#aes192-gcm"
@@ -73,15 +74,15 @@ const (
 	MethodTripleDESCBC = "http://www.w3.org/2001/04/xmlenc#tripledes-cbc"
 )
 
-//Well-known hash methods
+// Well-known hash methods
 const (
 	MethodSHA1   = "http://www.w3.org/2000/09/xmldsig#sha1"
 	MethodSHA256 = "http://www.w3.org/2000/09/xmldsig#sha256"
 	MethodSHA512 = "http://www.w3.org/2000/09/xmldsig#sha512"
 )
 
-//SHA-1 is commonly used for certificate fingerprints (openssl -fingerprint and ADFS thumbprint).
-//SHA-1 is sufficient for our purposes here (error message).
+// SHA-1 is commonly used for certificate fingerprints (openssl -fingerprint and ADFS thumbprint).
+// SHA-1 is sufficient for our purposes here (error message).
 func debugKeyFp(keyBytes []byte) string {
 	if len(keyBytes) < 1 {
 		return ""
@@ -100,8 +101,8 @@ func debugKeyFp(keyBytes []byte) string {
 	return ret
 }
 
-//DecryptSymmetricKey returns the private key contained in the EncryptedKey document
-func (ek *EncryptedKey) DecryptSymmetricKey(cert *tls.Certificate) (cipher.Block, error) {
+// DecryptSymmetricKey returns the private key contained in the EncryptedKey document
+func (ek *EncryptedKey) DecryptSymmetricKey(cert *tls.Certificate, algo string) (cipher.Block, error) {
 	if len(cert.Certificate) < 1 {
 		return nil, fmt.Errorf("decryption tls.Certificate has no public certs attached")
 	}
@@ -146,6 +147,14 @@ func (ek *EncryptedKey) DecryptSymmetricKey(cert *tls.Certificate) (cipher.Block
 			}
 		}
 
+		cipher := func(k []byte) (cipher.Block, error) {
+			if algo == MethodTripleDESCBC {
+				return des.NewTripleDESCipher(k)
+			} else {
+				return aes.NewCipher(k)
+			}
+		}
+
 		switch ek.EncryptionMethod.Algorithm {
 		case "":
 			return nil, fmt.Errorf("missing encryption algorithm")
@@ -155,7 +164,7 @@ func (ek *EncryptedKey) DecryptSymmetricKey(cert *tls.Certificate) (cipher.Block
 				return nil, fmt.Errorf("rsa internal error: %v", err)
 			}
 
-			b, err := aes.NewCipher(pt)
+			b, err := cipher(pt)
 			if err != nil {
 				return nil, err
 			}
@@ -175,7 +184,7 @@ func (ek *EncryptedKey) DecryptSymmetricKey(cert *tls.Certificate) (cipher.Block
 			//The RSA v1.5 Key Transport algorithm given below are those used in conjunction with TRIPLEDES
 			//Please also see https://www.w3.org/TR/xmlenc-core/#sec-Algorithms and
 			//https://www.w3.org/TR/xmlenc-core/#rsav15note.
-			b, err := aes.NewCipher(pt)
+			b, err := cipher(pt)
 			if err != nil {
 				return nil, err
 			}