[RSA] New methods:

- .make_key()
- .encode_key()

src/wolfcrypt/_build_ffi.py

@@ -130,6 +130,10 @@ ffi.cdef(
     int wc_RsaSetRNG(RsaKey* key, WC_RNG* rng);
     int wc_FreeRsaKey(RsaKey* key);
 
+    int wc_MakeRsaKey(RsaKey* key, int size, long e, WC_RNG* rng);
+    int wc_RsaKeyToDer(RsaKey* key, byte* output, word32 inLen);
+    int wc_RsaKeyToPublicDer(RsaKey* key, byte* output, word32 inLen);
+
     int wc_RsaPrivateKeyDecode(const byte*, word32*, RsaKey*, word32);
     int wc_RsaPublicKeyDecode(const byte*, word32*, RsaKey*, word32);
     int wc_RsaEncryptSize(RsaKey*);

src/wolfcrypt/ciphers.py

@@ -273,20 +273,21 @@ class _Rsa(object):  # pylint: disable=too-few-public-methods
 
 
 class RsaPublic(_Rsa):
-    def __init__(self, key):
+    def __init__(self, key=None):
+        if key != None:
             key = t2b(key)
 
         _Rsa.__init__(self)
 
         idx = _ffi.new("word32*")
         idx[0] = 0
-
         ret = _lib.wc_RsaPublicKeyDecode(key, idx,
                 self.native_object, len(key))
         if ret < 0:
             raise WolfCryptError("Invalid key error (%d)" % ret)
 
         self.output_size = _lib.wc_RsaEncryptSize(self.native_object)
+        self.size = len(key)
         if self.output_size <= 0:  # pragma: no cover
             raise WolfCryptError("Invalid key error (%d)" % self.output_size)
 
@@ -336,22 +337,61 @@ class RsaPublic(_Rsa):
 
 
 class RsaPrivate(RsaPublic):
-    def __init__(self, key):  # pylint: disable=super-init-not-called
-        key = t2b(key)
+    @classmethod
+    def make_key(cls, size, rng=Random()):
+        """
+        Generates a new key pair of desired length **size**.
+        """
+        rsa = cls(None)
+        if rsa == None:  # pragma: no cover
+            raise WolfCryptError("Invalid key error (%d)" % ret)
+
+        ret = _lib.wc_MakeRsaKey(rsa.native_object, size, 65537, rng.native_object)
+        if ret < 0:
+            raise WolfCryptError("Key generation error (%d)" % ret)
+        rsa.output_size = _lib.wc_RsaEncryptSize(rsa.native_object)
+        rsa.size = size
+        if rsa.output_size <= 0:  # pragma: no cover
+            raise WolfCryptError("Invalid key size error (%d)" % rsa.output_size)
+        return rsa
+    def __init__(self, key = None):  # pylint: disable=super-init-not-called
 
         _Rsa.__init__(self)  # pylint: disable=non-parent-init-called
 
         idx = _ffi.new("word32*")
         idx[0] = 0
 
+        if key != None:
+            key = t2b(key)
             ret = _lib.wc_RsaPrivateKeyDecode(key, idx,
                                               self.native_object, len(key))
             if ret < 0:
                 raise WolfCryptError("Invalid key error (%d)" % ret)
 
+            self.size = len(key)
             self.output_size = _lib.wc_RsaEncryptSize(self.native_object)
             if self.output_size <= 0:  # pragma: no cover
-            raise WolfCryptError("Invalid key error (%d)" % self.output_size)
+                raise WolfCryptError("Invalid key size error (%d)" % self.output_size)
+
+    def encode_key(self):
+        """
+        Encodes the RSA private and public keys in an ASN sequence.
+
+        Returns the encoded key.
+        """
+        priv = _ffi.new("byte[%d]" % (self.size * 4))
+        pub = _ffi.new("byte[%d]" % (self.size * 4))
+
+
+        ret = _lib.wc_RsaKeyToDer(self.native_object, priv, self.size)
+        if ret <= 0:  # pragma: no cover
+            raise WolfCryptError("Private RSA key error (%d)" % ret)
+        privlen = ret
+        ret = _lib.wc_RsaKeyToPublicDer(self.native_object, pub, self.size)
+        if ret <= 0:  # pragma: no cover
+            raise WolfCryptError("Public RSA key encode error (%d)" % ret)
+        publen = ret
+        return _ffi.buffer(priv, privlen)[:], _ffi.buffer(pub, publen)[:]
 
     def decrypt(self, ciphertext):
         """

tests/test_ciphers.py

@@ -213,6 +213,9 @@ def test_new_rsa_raises(vectors):
     with pytest.raises(WolfCryptError):
         RsaPublic(vectors[RsaPublic].key[:-1])    # invalid key length
 
+    with pytest.raises(WolfCryptError):           # invalid key size
+        RsaPrivate.make_key(16384)
+
 
 def test_rsa_encrypt_decrypt(rsa_private, rsa_public):
     plaintext = t2b("Everyone gets Friday off.")
@@ -247,17 +250,14 @@ def test_rsa_sign_verify(rsa_private, rsa_public):
     assert 1024 / 8 == len(signature) == rsa_private.output_size
     assert plaintext == rsa_private.verify(signature)
 
-
 @pytest.fixture
 def ecc_private(vectors):
     return EccPrivate(vectors[EccPrivate].key)
 
-
 @pytest.fixture
 def ecc_public(vectors):
     return EccPublic(vectors[EccPublic].key)
 
-
 def test_new_ecc_raises(vectors):
     with pytest.raises(WolfCryptError):
         EccPrivate(vectors[EccPrivate].key[:-1])  # invalid key length