Merge from trunk

[plcapi.git] / trunk / PLC / GPG.py

diff --git a/trunk/PLC/GPG.py b/trunk/PLC/GPG.py
new file mode 100644 (file)
index 0000000..2499bab
--- /dev/null
+++ b/trunk/PLC/GPG.py
@@ -0,0 +1,183 @@
+#
+# Python "binding" for GPG. I'll write GPGME bindings eventually. The
+# intent is to use GPG to sign method calls, as a way of identifying
+# and authenticating peers. Calls should still go over an encrypted
+# transport such as HTTPS, with certificate checking.
+#
+# Mark Huang <mlhuang@cs.princeton.edu>
+# Copyright (C) 2006 The Trustees of Princeton University
+#
+# $Id$
+#
+
+import os
+import xmlrpclib
+import shutil
+from types import StringTypes
+from StringIO import StringIO
+from xml.dom import minidom
+from xml.dom.ext import Canonicalize
+from subprocess import Popen, PIPE, call
+from tempfile import NamedTemporaryFile, mkdtemp
+
+from PLC.Faults import *
+
+def canonicalize(args, methodname = None, methodresponse = False):
+    """
+    Returns a canonicalized XML-RPC representation of the specified
+    method call (methodname != None) or response (methodresponse =
+    True).
+    """
+
+    xml = xmlrpclib.dumps(args, methodname, methodresponse, encoding = 'utf-8', allow_none = 1)
+    dom = minidom.parseString(xml)
+
+    # Canonicalize(), though it claims to, does not encode unicode
+    # nodes to UTF-8 properly and throws an exception unless you write
+    # the stream to a file object, so just encode it ourselves.
+    buf = StringIO()
+    Canonicalize(dom, output = buf)
+    xml = buf.getvalue().encode('utf-8')
+
+    return xml
+
+def gpg_export(keyring, armor = True):
+    """
+    Exports the specified public keyring file.
+    """
+
+    homedir = mkdtemp()
+    args = ["gpg", "--batch", "--no-tty",
+            "--homedir", homedir,
+            "--no-default-keyring",
+            "--keyring", keyring,
+            "--export"]
+    if armor:
+        args.append("--armor")
+
+    p = Popen(args, stdin = PIPE, stdout = PIPE, stderr = PIPE, close_fds = True)
+    export = p.stdout.read()
+    err = p.stderr.read()
+    rc = p.wait()
+
+    # Clean up
+    shutil.rmtree(homedir)
+
+    if rc:
+        raise PLCAuthenticationFailure, "GPG export failed with return code %d: %s" % (rc, err)
+
+    return export
+
+def gpg_sign(args, secret_keyring, keyring, methodname = None, methodresponse = False, detach_sign = True):
+    """
+    Signs the specified method call (methodname != None) or response
+    (methodresponse == True) using the specified GPG keyring files. If
+    args is not a tuple representing the arguments to the method call
+    or the method response value, then it should be a string
+    representing a generic message to sign (detach_sign == True) or
+    sign/encrypt (detach_sign == False) specified). Returns the
+    detached signature (detach_sign == True) or signed/encrypted
+    message (detach_sign == False).
+    """
+
+    # Accept either an opaque string blob or a Python tuple
+    if isinstance(args, StringTypes):
+        message = args
+    elif isinstance(args, tuple):
+        message = canonicalize(args, methodname, methodresponse)
+
+    # Use temporary trustdb
+    homedir = mkdtemp()
+
+    cmd = ["gpg", "--batch", "--no-tty",
+           "--homedir", homedir,
+           "--no-default-keyring",
+           "--secret-keyring", secret_keyring,
+           "--keyring", keyring,
+           "--armor"]
+
+    if detach_sign:
+        cmd.append("--detach-sign")
+    else:
+        cmd.append("--sign")
+
+    p = Popen(cmd, stdin = PIPE, stdout = PIPE, stderr = PIPE)
+    p.stdin.write(message)
+    p.stdin.close()
+    signature = p.stdout.read()
+    err = p.stderr.read()
+    rc = p.wait()
+
+    # Clean up
+    shutil.rmtree(homedir)
+
+    if rc:
+        raise PLCAuthenticationFailure, "GPG signing failed with return code %d: %s" % (rc, err)
+
+    return signature
+
+def gpg_verify(args, key, signature = None, methodname = None, methodresponse = False):
+    """
+    Verifies the signature of the specified method call (methodname !=
+    None) or response (methodresponse = True) using the specified
+    public key material. If args is not a tuple representing the
+    arguments to the method call or the method response value, then it
+    should be a string representing a generic message to verify (if
+    signature is specified) or verify/decrypt (if signature is not
+    specified).
+    """
+
+    # Accept either an opaque string blob or a Python tuple
+    if isinstance(args, StringTypes):
+        message = args
+    else:
+        message = canonicalize(args, methodname, methodresponse)
+
+    # Write public key to temporary file
+    if os.path.exists(key):
+        keyfile = None
+        keyfilename = key
+    else:
+        keyfile = NamedTemporaryFile(suffix = '.pub')
+        keyfile.write(key)
+        keyfile.flush()
+        keyfilename = keyfile.name
+
+    # Import public key into temporary keyring
+    homedir = mkdtemp()
+    call(["gpg", "--batch", "--no-tty", "--homedir", homedir, "--import", keyfilename],
+         stdin = PIPE, stdout = PIPE, stderr = PIPE)
+
+    cmd = ["gpg", "--batch", "--no-tty",
+           "--homedir", homedir]
+
+    if signature is not None:
+        # Write detached signature to temporary file
+        sigfile = NamedTemporaryFile()
+        sigfile.write(signature)
+        sigfile.flush()
+        cmd += ["--verify", sigfile.name, "-"]
+    else:
+        # Implicit signature
+        sigfile = None
+        cmd.append("--decrypt")
+
+    p = Popen(cmd, stdin = PIPE, stdout = PIPE, stderr = PIPE)
+    p.stdin.write(message)
+    p.stdin.close()
+    if signature is None:
+        message = p.stdout.read()
+    err = p.stderr.read()
+    rc = p.wait()
+
+    # Clean up
+    shutil.rmtree(homedir)
+    if sigfile:
+        sigfile.close()
+    if keyfile:
+        keyfile.close()
+
+    if rc:
+        raise PLCAuthenticationFailure, "GPG verification failed with return code %d: %s" % (rc, err)
+
+    return message