Update libs

libs/rsa/pem.py

@@ -0,0 +1,120 @@
+# -*- coding: utf-8 -*-
+#
+#  Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+'''Functions that load and write PEM-encoded files.'''
+
+import base64
+from rsa._compat import b, is_bytes
+
+def _markers(pem_marker):
+    '''
+    Returns the start and end PEM markers
+    '''
+
+    if is_bytes(pem_marker):
+        pem_marker = pem_marker.decode('utf-8')
+
+    return (b('-----BEGIN %s-----' % pem_marker),
+            b('-----END %s-----' % pem_marker))
+
+def load_pem(contents, pem_marker):
+    '''Loads a PEM file.
+
+    @param contents: the contents of the file to interpret
+    @param pem_marker: the marker of the PEM content, such as 'RSA PRIVATE KEY'
+        when your file has '-----BEGIN RSA PRIVATE KEY-----' and
+        '-----END RSA PRIVATE KEY-----' markers.
+
+    @return the base64-decoded content between the start and end markers.
+
+    @raise ValueError: when the content is invalid, for example when the start
+        marker cannot be found.
+
+    '''
+
+    (pem_start, pem_end) = _markers(pem_marker)
+
+    pem_lines = []
+    in_pem_part = False
+
+    for line in contents.splitlines():
+        line = line.strip()
+
+        # Skip empty lines
+        if not line:
+            continue
+
+        # Handle start marker
+        if line == pem_start:
+            if in_pem_part:
+                raise ValueError('Seen start marker "%s" twice' % pem_start)
+
+            in_pem_part = True
+            continue
+
+        # Skip stuff before first marker
+        if not in_pem_part:
+            continue
+
+        # Handle end marker
+        if in_pem_part and line == pem_end:
+            in_pem_part = False
+            break
+
+        # Load fields
+        if b(':') in line:
+            continue
+
+        pem_lines.append(line)
+
+    # Do some sanity checks
+    if not pem_lines:
+        raise ValueError('No PEM start marker "%s" found' % pem_start)
+
+    if in_pem_part:
+        raise ValueError('No PEM end marker "%s" found' % pem_end)
+
+    # Base64-decode the contents
+    pem = b('').join(pem_lines)
+    return base64.decodestring(pem)
+
+
+def save_pem(contents, pem_marker):
+    '''Saves a PEM file.
+
+    @param contents: the contents to encode in PEM format
+    @param pem_marker: the marker of the PEM content, such as 'RSA PRIVATE KEY'
+        when your file has '-----BEGIN RSA PRIVATE KEY-----' and
+        '-----END RSA PRIVATE KEY-----' markers.
+
+    @return the base64-encoded content between the start and end markers.
+
+    '''
+
+    (pem_start, pem_end) = _markers(pem_marker)
+
+    b64 = base64.encodestring(contents).replace(b('\n'), b(''))
+    pem_lines = [pem_start]
+    
+    for block_start in range(0, len(b64), 64):
+        block = b64[block_start:block_start + 64]
+        pem_lines.append(block)
+
+    pem_lines.append(pem_end)
+    pem_lines.append(b(''))
+
+    return b('\n').join(pem_lines)
+