# base64 Starlark module for working with base64 library. This module provides functions for encoding binary data to printable ASCII characters and decoding such encodings back to binary data. It provides encoding and decoding functions for the encodings specified in RFC 4648, which defines the Base16, Base32, and Base64 algorithms, and for the de-facto standard Ascii85 and Base85 encodings. The RFC 4648 encodings are suitable for encoding binary data so that it can be safely sent by email, used as parts of URLs, or included as part of an HTTP POST request. The encoding algorithm is not the same as the uuencode program. There are two interfaces provided by this module. The modern interface supports encoding bytes-like objects to ASCII bytes, and decoding bytes-like objects or strings containing ASCII to bytes. Both base-64 alphabets defined in RFC 4648 (normal, and URL- and filesystem-safe) are supported. The legacy interface does not support decoding from strings, but it does provide functions for encoding and decoding to and from file objects. It only supports the Base64 standard alphabet, and it adds newlines every 76 characters as per RFC 2045. Note that if you are looking for RFC 2045 support you probably want to be looking at the email package instead. Similar to [base64 in Python](https://docs.python.org/3/library/base64.html). ## base64.b16decode(s, casefold=False) Decode the Base16 encoded bytes-like object or ASCII string s and return the decoded bytes. Example: ```python base64.b16decode(b'6C61726B79') b'larky' ``` **Parameters:** * **s** – bytes string. * **casefold** – optional casefold is a flag specifying whether a lowercase alphabet is acceptable as input. For security purposes, the default is False. *Returns:* decoded byte string. binascii.Error is raised if s were incorrectly padded or if there are non-alphabet characters present in the string. ## base64.b16encode(s) Encode the bytes-like object s using Base16 and return the encoded bytes. Example: ```python base64.b16encode(b'larky') b'6C61726B79' ``` **Parameters:** **s** – byte string. *Returns:* encoded byte string. ## base64.b32decode(s, casefold=False, map01=None) Decode the Base32 encoded bytes-like object or ASCII string s and return the decoded bytes. Example: ```python base64.b32decode(b'NRQXE23Z') b'larky'' ``` **Parameters:** * **s** – byte string. * **casefold** – optional casefold is a flag specifying whether a lowercase alphabet is acceptable as input. For security purposes, the default is False. * **map01** – RFC 4648 allows for optional mapping of the digit 0 (zero) to the letter O (oh), and for optional mapping of the digit 1 (one) to either the letter I (eye) or letter L (el). The optional argument map01 when not None, specifies which letter the digit 1 should be mapped to (when map01 is not None, the digit 0 is always mapped to the letter O). For security purposes the default is None, so that 0 and 1 are not allowed in the input. *Returns:* decoded byte string. binascii.Error is raised if the input is incorrectly padded or if there are non-alphabet characters present in the input. ## base64.b32encode(s) Encode the bytes-like object s using Base32 and return the encoded bytes. Example: ```python base64.b32encode(b'larky') b'NRQXE23Z'' ``` **Parameters:** **s** – byte string. *Returns:* encoded byte string. ## base64.b64decode(s, altchars=None, validate=False) Decode the Base64 encoded bytes-like object or ASCII string s and return the decoded bytes. Example: ```python base64.b64decode(b'bGFya3k=') b'larky' ``` **Parameters:** * **s** – byte string * **altchars** – optional altchars must be a bytes-like object or ASCII string of at least length 2 (additional characters are ignored) which specifies the alternative alphabet used instead of the + and / characters. * **validate** – if validate is False (the default), characters that are neither in the normal base-64 alphabet nor the alternative alphabet are discarded prior to the padding check. If validate is True, these non-alphabet characters in the input result in a binascii.Error. *Returns:* decoded string. A binascii.Error is raised if s is incorrectly padded. ## base64.b64encode(s, altchars=None) Encode the bytes-like object s using Base64 and return the encoded bytes. Example: ```python base64.b64encode(b'larky') b'bGFya3k=' ``` **Parameters:** * **s** – byte string. * **altchars** – optional altchars must be a bytes-like object of at least length 2 (additional characters are ignored) which specifies an alternative alphabet for the + and / characters. This allows an application to e.g. generate URL or filesystem safe Base64 strings. The default is None, for which the standard Base64 alphabet is used. *Returns:* encoded byte string. ## base64.decodebytes(s) Decode the bytes-like object s, which must contain one or more lines of base64 encoded data, and return the decoded bytes. Example: ```python base64.decodebytes(b'bGFya3k=\n') b'larky' ``` **Parameters:** **s** – bytes string. *Returns:* decoded byte string. ## base64.encodebytes(s) Encode the bytes-like object s, which can contain arbitrary binary data, and return bytes containing the base64-encoded data, with newlines inserted after every 76 bytes of output, and ensuring that there is a trailing newline, as per RFC 2045 (MIME). Example: ```python base64.encodebytes(b'larky') b'bGFya3k=\n' ``` **Parameters:** **s** – bytes string. *Returns:* encoded byte string. ## base64.standard\_b64decode(s) Decode bytes-like object or ASCII string s using the standard Base64 alphabet and return the decoded bytes. **Parameters:** **s** – byte string. *Returns:* decoded byte string. binascii.Error is raised if the input is incorrectly padded or if there are non-alphabet characters present in the input. ## base64.standard\_b64encode(s) Encode bytes-like object s using the standard Base64 alphabet and return the encoded bytes. **Parameters:** **s** – byte string. *Returns:* encoded byte string. ## base64.urlsafe\_b64decode(s) Decode bytes-like object or ASCII string s using the URL- and filesystem-safe alphabet, which substitutes - instead of + and \_ instead of / in the standard Base64 alphabet, and return the decoded bytes. **Parameters:** **s** – byte string. *Returns:* decoded byte string. binascii.Error is raised if the input is incorrectly padded or if there are non-alphabet characters present in the input. ## base64.urlsafe\_b64encode(s) Encode bytes-like object s using the URL- and filesystem-safe alphabet, which substitutes - instead of + and \_ instead of / in the standard Base64 alphabet, and return the encoded bytes. The result can still contain =. **Parameters:** **s** – byte string. *Returns:* encoded byte string. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.verygoodsecurity.com/vault/developer-tools/larky/library-api/base64.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.