diff --git a/paramiko/dsskey.py b/paramiko/dsskey.py
index a004597..2677e4a 100644
--- a/paramiko/dsskey.py
+++ b/paramiko/dsskey.py
@@ -36,14 +36,16 @@ class DSSKey (PKey):
     Representation of a DSS key which can be used to sign an verify SSH2
     data.
     """
-    
-    p = None
-    q = None
-    g = None
-    y = None
-    x = None
 
-    def __init__(self, msg=None, data=None, filename=None, password=None, vals=None):
+    def __init__(self, msg=None, data=None, filename=None, password=None, vals=None, file_obj=None):
+        self.p = None
+        self.q = None
+        self.g = None
+        self.y = None
+        self.x = None
+        if file_obj is not None:
+            self._from_private_key(file_obj, password)
+            return
         if filename is not None:
             self._from_private_key_file(filename, password)
             return
@@ -171,9 +173,16 @@ class DSSKey (PKey):
 
 
     def _from_private_key_file(self, filename, password):
+        data = self._read_private_key_file('DSA', filename, password)
+        self._decode_key(data)
+    
+    def _from_private_key(self, file_obj, password):
+        data = self._read_private_key('DSA', file_obj, password)
+        self._decode_key(data)
+    
+    def _decode_key(self, data):
         # private key file contains:
         # DSAPrivateKey = { version = 0, p, q, g, y, x }
-        data = self._read_private_key_file('DSA', filename, password)
         try:
             keylist = BER(data).decode()
         except BERException, x:
diff --git a/paramiko/pkey.py b/paramiko/pkey.py
index 053869e..e1aef88 100644
--- a/paramiko/pkey.py
+++ b/paramiko/pkey.py
@@ -197,6 +197,30 @@ class PKey (object):
         return key
     from_private_key_file = classmethod(from_private_key_file)
 
+    def from_private_key(cls, file_obj, password=None):
+        """
+        Create a key object by reading a private key from a file (or file-like)
+        object.  If the private key is encrypted and C{password} is not C{None},
+        the given password will be used to decrypt the key (otherwise
+        L{PasswordRequiredException} is thrown).
+        
+        @param file_obj: the file to read from
+        @type file_obj: file
+        @param password: an optional password to use to decrypt the key, if it's
+            encrypted
+        @type password: str
+        @return: a new key object based on the given private key
+        @rtype: L{PKey}
+        
+        @raise IOError: if there was an error reading the key
+        @raise PasswordRequiredException: if the private key file is encrypted,
+            and C{password} is C{None}
+        @raise SSHException: if the key file is invalid
+        """
+        key = cls(file_obj=file_obj, password=password)
+        return key
+    from_private_key = classmethod(from_private_key)
+
     def write_private_key_file(self, filename, password=None):
         """
         Write private key contents into a file.  If the password is not
@@ -251,8 +275,12 @@ class PKey (object):
         @raise SSHException: if the key file is invalid.
         """
         f = open(filename, 'r')
-        lines = f.readlines()
+        data = self._read_private_key(tag, f, password)
         f.close()
+        return data
+    
+    def _read_private_key(self, tag, f, password=None):
+        lines = f.readlines()
         start = 0
         while (start < len(lines)) and (lines[start].strip() != '-----BEGIN ' + tag + ' PRIVATE KEY-----'):
             start += 1
diff --git a/paramiko/rsakey.py b/paramiko/rsakey.py
index 414815c..8bd925d 100644
--- a/paramiko/rsakey.py
+++ b/paramiko/rsakey.py
@@ -38,13 +38,15 @@ class RSAKey (PKey):
     data.
     """
 
-    n = None
-    e = None
-    d = None
-    p = None
-    q = None
-    
-    def __init__(self, msg=None, data=None, filename=None, password=None, vals=None):
+    def __init__(self, msg=None, data=None, filename=None, password=None, vals=None, file_obj=None):
+        self.n = None
+        self.e = None
+        self.d = None
+        self.p = None
+        self.q = None
+        if file_obj is not None:
+            self._from_private_key(file_obj, password)
+            return
         if filename is not None:
             self._from_private_key_file(filename, password)
             return
@@ -159,9 +161,16 @@ class RSAKey (PKey):
         return '\x00\x01' + filler + '\x00' + SHA1_DIGESTINFO + data
 
     def _from_private_key_file(self, filename, password):
+        data = self._read_private_key_file('RSA', filename, password)
+        self._decode_key(data)
+    
+    def _from_private_key(self, file_obj, password):
+        data = self._read_private_key('RSA', file_obj, password)
+        self._decode_key(data)
+    
+    def _decode_key(self, data):
         # private key file contains:
         # RSAPrivateKey = { version = 0, n, e, d, p, q, d mod p-1, d mod q-1, q**-1 mod p }
-        data = self._read_private_key_file('RSA', filename, password)
         try:
             keylist = BER(data).decode()
         except BERException:
diff --git a/tests/test_pkey.py b/tests/test_pkey.py
index d4b826a..d5419cd 100644
--- a/tests/test_pkey.py
+++ b/tests/test_pkey.py
@@ -91,6 +91,9 @@ class KeyTest (unittest.TestCase):
         s = StringIO.StringIO()
         key.write_private_key(s)
         self.assertEquals(RSA_PRIVATE_OUT, s.getvalue()) 
+        s.seek(0)
+        key2 = RSAKey.from_private_key(s)
+        self.assertEquals(key, key2)
 
     def test_3_load_rsa_password(self):
         key = RSAKey.from_private_key_file('tests/test_rsa_password.key', 'television')
@@ -113,6 +116,9 @@ class KeyTest (unittest.TestCase):
         s = StringIO.StringIO()
         key.write_private_key(s)
         self.assertEquals(DSS_PRIVATE_OUT, s.getvalue())
+        s.seek(0)
+        key2 = DSSKey.from_private_key(s)
+        self.assertEquals(key, key2)
 
     def test_5_load_dss_password(self):
         key = DSSKey.from_private_key_file('tests/test_dss_password.key', 'television')