1 files changed, 159 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/ellipticcurve/utils/der.py b/.venv/lib/python3.12/site-packages/ellipticcurve/utils/der.py
new file mode 100644
index 00000000..84546aea
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/ellipticcurve/utils/der.py
@@ -0,0 +1,159 @@
+from datetime import datetime
+from .oid import oidToHex, oidFromHex
+from .binary import hexFromInt, intFromHex, byteStringFromHex, bitsFromHex
+
+
+class DerFieldType:
+
+    integer = "integer"
+    bitString = "bitString"
+    octetString = "octetString"
+    null = "null"
+    object = "object"
+    printableString = "printableString"
+    utcTime = "utcTime"
+    sequence = "sequence"
+    set = "set"
+    oidContainer = "oidContainer"
+    publicKeyPointContainer = "publicKeyPointContainer"
+
+
+_hexTagToType = {
+    "02": DerFieldType.integer,
+    "03": DerFieldType.bitString,
+    "04": DerFieldType.octetString,
+    "05": DerFieldType.null,
+    "06": DerFieldType.object,
+    "13": DerFieldType.printableString,
+    "17": DerFieldType.utcTime,
+    "30": DerFieldType.sequence,
+    "31": DerFieldType.set,
+    "a0": DerFieldType.oidContainer,
+    "a1": DerFieldType.publicKeyPointContainer,
+}
+_typeToHexTag = {v: k for k, v in _hexTagToType.items()}
+
+
+def encodeConstructed(*encodedValues):
+    return encodePrimitive(DerFieldType.sequence, "".join(encodedValues))
+
+
+def encodePrimitive(tagType, value):
+    if tagType == DerFieldType.integer:
+        value = _encodeInteger(value)
+    if tagType == DerFieldType.object:
+        value = oidToHex(value)
+    return "{tag}{size}{value}".format(tag=_typeToHexTag[tagType], size=_generateLengthBytes(value), value=value)
+
+
+def parse(hexadecimal):
+    if not hexadecimal:
+        return []
+    typeByte, hexadecimal = hexadecimal[:2], hexadecimal[2:]
+    length, lengthBytes = _readLengthBytes(hexadecimal)
+    content, hexadecimal = hexadecimal[lengthBytes: lengthBytes + length], hexadecimal[lengthBytes + length:]
+    if len(content) < length:
+        raise Exception("missing bytes in DER parse")
+
+    tagData = _getTagData(typeByte)
+    if tagData["isConstructed"]:
+        content = parse(content)
+
+    valueParser = {
+        DerFieldType.null: _parseNull,
+        DerFieldType.object: _parseOid,
+        DerFieldType.utcTime: _parseTime,
+        DerFieldType.integer: _parseInteger,
+        DerFieldType.printableString: _parseString,
+    }.get(tagData["type"], _parseAny)
+    return [valueParser(content)] + parse(hexadecimal)
+
+
+def _parseAny(hexadecimal):
+    return hexadecimal
+
+
+def _parseOid(hexadecimal):
+    return tuple(oidFromHex(hexadecimal))
+
+
+def _parseTime(hexadecimal):
+    string = _parseString(hexadecimal)
+    return datetime.strptime(string, "%y%m%d%H%M%SZ")
+
+
+def _parseString(hexadecimal):
+    return byteStringFromHex(hexadecimal).decode()
+
+
+def _parseNull(_content):
+    return None
+
+
+def _parseInteger(hexadecimal):
+    integer = intFromHex(hexadecimal)
+    bits = bitsFromHex(hexadecimal[0])
+    if bits[0] == "0":  # negative numbers are encoded using two's complement
+        return integer
+    bitCount = 4 * len(hexadecimal)
+    return integer - (2 ** bitCount)
+
+
+def _encodeInteger(number):
+    hexadecimal = hexFromInt(abs(number))
+    if number < 0:
+        bitCount = 4 * len(hexadecimal)
+        twosComplement = (2 ** bitCount) + number
+        return hexFromInt(twosComplement)
+    bits = bitsFromHex(hexadecimal[0])
+    if bits[0] == "1":  # if first bit was left as 1, number would be parsed as a negative integer with two's complement
+        hexadecimal = "00" + hexadecimal
+    return hexadecimal
+
+
+def _readLengthBytes(hexadecimal):
+    lengthBytes = 2
+    lengthIndicator = intFromHex(hexadecimal[0:lengthBytes])
+    isShortForm = lengthIndicator < 128  # checks if first bit of byte is 1 (a.k.a. short-form)
+    if isShortForm:
+        length = lengthIndicator * 2
+        return length, lengthBytes
+
+    lengthLength = lengthIndicator - 128  # nullifies first bit of byte (only used as long-form flag)
+    if lengthLength == 0:
+        raise Exception("indefinite length encoding located in DER")
+    lengthBytes += 2 * lengthLength
+    length = intFromHex(hexadecimal[2:lengthBytes]) * 2
+    return length, lengthBytes
+
+
+def _generateLengthBytes(hexadecimal):
+    size = len(hexadecimal) // 2
+    length = hexFromInt(size)
+    if size < 128:  # checks if first bit of byte should be 0 (a.k.a. short-form flag)
+        return length.zfill(2)
+    lengthLength = 128 + len(length) // 2  # +128 sets the first bit of the byte as 1 (a.k.a. long-form flag)
+    return hexFromInt(lengthLength) + length
+
+
+def _getTagData(tag):
+    bits = bitsFromHex(tag)
+    bit8, bit7, bit6 = bits[:3]
+
+    tagClass = {
+        "0": {
+            "0": "universal",
+            "1": "application",
+        },
+        "1": {
+            "0": "context-specific",
+            "1": "private",
+        },
+    }[bit8][bit7]
+    isConstructed = bit6 == "1"
+
+    return {
+        "class": tagClass,
+        "isConstructed": isConstructed,
+        "type": _hexTagToType.get(tag),
+    }