# # Copyright (c) nexB Inc. and others. All rights reserved. # SPDX-License-Identifier: Apache-2.0 # See http://www.apache.org/licenses/LICENSE-2.0 for the license text. # See https://github.com/nexB/commoncode for support or download. # See https://aboutcode.org for more information about nexB OSS projects. # from base64 import standard_b64decode as stddecode from base64 import urlsafe_b64encode as b64encode """ Numbers to bytes or strings and URLs coder/decoders. """ c2i = lambda c: c i2c = lambda i: bytes([i]) def num_to_bin(num): """ Convert a `num` integer or long to a binary string byte-ordered such that the least significant bytes are at the beginning of the string (aka. big endian). """ # Zero is not encoded but returned as an empty value if num == 0: return b'\x00' return num.to_bytes((num.bit_length() + 7) // 8, 'big') def bin_to_num(binstr): """ Convert a big endian byte-ordered binary string to an integer or long. """ return int.from_bytes(binstr, byteorder='big', signed=False) def urlsafe_b64encode(s): """ Encode a binary string to a url safe base64 encoding. """ return b64encode(s) def urlsafe_b64decode(b64): """ Decode a url safe base64-encoded string. Note that we use stddecode to work around a bug in the standard library. """ b = b64.replace(b'-', b'+').replace(b'_', b'/') return stddecode(b) def urlsafe_b64encode_int(num): """ Encode a number (int or long) in url safe base64. """ return b64encode(num_to_bin(num))