Initial commit

venv/Lib/site-packages/rsa/pem.py

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+#  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
+#
+#      https://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
+import typing
+
+# Should either be ASCII strings or bytes.
+FlexiText = typing.Union[str, bytes]
+
+
+def _markers(pem_marker: FlexiText) -> typing.Tuple[bytes, bytes]:
+    """
+    Returns the start and end PEM markers, as bytes.
+    """
+
+    if not isinstance(pem_marker, bytes):
+        pem_marker = pem_marker.encode("ascii")
+
+    return (
+        b"-----BEGIN " + pem_marker + b"-----",
+        b"-----END " + pem_marker + b"-----",
+    )
+
+
+def _pem_lines(contents: bytes, pem_start: bytes, pem_end: bytes) -> typing.Iterator[bytes]:
+    """Generator over PEM lines between pem_start and pem_end."""
+
+    in_pem_part = False
+    seen_pem_start = 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 "%r" twice' % pem_start)
+
+            in_pem_part = True
+            seen_pem_start = 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
+
+        yield line
+
+    # Do some sanity checks
+    if not seen_pem_start:
+        raise ValueError('No PEM start marker "%r" found' % pem_start)
+
+    if in_pem_part:
+        raise ValueError('No PEM end marker "%r" found' % pem_end)
+
+
+def load_pem(contents: FlexiText, pem_marker: FlexiText) -> bytes:
+    """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.
+
+    """
+
+    # We want bytes, not text. If it's text, it can be converted to ASCII bytes.
+    if not isinstance(contents, bytes):
+        contents = contents.encode("ascii")
+
+    (pem_start, pem_end) = _markers(pem_marker)
+    pem_lines = [line for line in _pem_lines(contents, pem_start, pem_end)]
+
+    # Base64-decode the contents
+    pem = b"".join(pem_lines)
+    return base64.standard_b64decode(pem)
+
+
+def save_pem(contents: bytes, pem_marker: FlexiText) -> bytes:
+    """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, as bytes.
+
+    """
+
+    (pem_start, pem_end) = _markers(pem_marker)
+
+    b64 = base64.standard_b64encode(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)