diff --git a/key.go b/key.go
index cc17f5fc..8fcc2e90 100644
--- a/key.go
+++ b/key.go
@@ -19,6 +19,9 @@ package openssl
 // #include <openssl/evp.h>
 // #include <openssl/ssl.h>
 // #include <openssl/conf.h>
+// #include <openssl/engine.h>
+// #include <openssl/rsa.h>
+// #include <openssl/crypto.h>
 //
 // int EVP_SignInit_not_a_macro(EVP_MD_CTX *ctx, const EVP_MD *type) {
 //     return EVP_SignInit(ctx, type);
@@ -86,6 +89,9 @@ type PrivateKey interface {
 	// MarshalPKCS1PrivateKeyDER converts the private key to DER-encoded PKCS1
 	// format
 	MarshalPKCS1PrivateKeyDER() (der_block []byte, err error)
+
+	// GetModulus returns private key modulus
+	GetModulus() (modulus []byte, err error)
 }
 
 type pKey struct {
@@ -193,6 +199,22 @@ func (key *pKey) MarshalPKIXPublicKeyPEM() (pem_block []byte,
 	return ioutil.ReadAll(asAnyBio(bio))
 }
 
+func (key *pKey) GetModulus() ([]byte, error) {
+	rsa := (*C.RSA)(C.EVP_PKEY_get1_RSA(key.key))
+	if rsa == nil {
+		return nil, errors.New("failed getting rsa key")
+	}
+	defer C.RSA_free(rsa)
+
+	m := C.BN_bn2hex(rsa.n)
+	if m == nil {
+		return nil, errors.New("failed to find RSA key modulus")
+	}
+	defer C.CRYPTO_free(unsafe.Pointer(m))
+
+	return ([]byte)(C.GoString(m)), nil
+}
+
 func (key *pKey) MarshalPKIXPublicKeyDER() (der_block []byte,
 	err error) {
 	bio := C.BIO_new(C.BIO_s_mem())
@@ -211,6 +233,20 @@ func (key *pKey) MarshalPKIXPublicKeyDER() (der_block []byte,
 	return ioutil.ReadAll(asAnyBio(bio))
 }
 
+// LoadPrivateKeyFromEngine loads a provate key from an OpenSSL ENGINE
+func LoadPrivateKeyFromEngine(e *Engine, key_id []byte) (PrivateKey, error) {
+	key := C.ENGINE_load_private_key(e.e, (*C.char)(unsafe.Pointer(&key_id[0])), nil, nil)
+	if key == nil {
+		return nil, errors.New("Could not load private key from engine")
+	}
+
+	p := &pKey{key: key}
+	runtime.SetFinalizer(p, func(p *pKey) {
+		C.EVP_PKEY_free(p.key)
+	})
+	return p, nil
+}
+
 // LoadPrivateKeyFromPEM loads a private key from a PEM-encoded block.
 func LoadPrivateKeyFromPEM(pem_block []byte) (PrivateKey, error) {
 	if len(pem_block) == 0 {
diff --git a/key_test.go b/key_test.go
index 0af90128..6d5c383f 100644
--- a/key_test.go
+++ b/key_test.go
@@ -174,3 +174,19 @@ func TestSign(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestModulus(t *testing.T) {
+	key, err := LoadPrivateKeyFromPEM(keyBytes)
+	if err != nil {
+		t.Fatal(err)
+	}
+	modulus, err := key.GetModulus()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(modulus, keyModulus) {
+		ioutil.WriteFile("calculated", []byte(hex.Dump(modulus)), 0644)
+		ioutil.WriteFile("hardcoded", []byte(hex.Dump(keyModulus)), 0644)
+		t.Fatal("invalid private key modulus bytes")
+	}
+}
diff --git a/ssl_test.go b/ssl_test.go
index f83225de..4754916e 100644
--- a/ssl_test.go
+++ b/ssl_test.go
@@ -81,6 +81,8 @@ ucCCa4lOGgPtXJ0Qf1c8yq5vh4yqkQjrgUTkr+CFDGR6y4CxmNDQxEMYIajaIiSY
 qmgvgyRayemfO2zR0CPgC6wSoGBth+xW6g+WA8y0z76ZSaWpFi8lVM4=
 -----END RSA PRIVATE KEY-----
 `)
+
+	keyModulus = []byte(`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`)
 )
 
 func NetPipe(t testing.TB) (net.Conn, net.Conn) {