`. It only supports the Base64 standard alphabet, and it adds newlines every 76 characters as per `2045`. Note that if you are looking for `2045` support you probably want to be looking at the `email` package instead.

3.3 ASCII-only Unicode strings are now accepted by the decoding functions of the modern interface.

3.4 Any `bytes-like objects ` are now accepted by all encoding and decoding functions in this module. Ascii85/Base85 support added.

## RFC 4648 Encodings The `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.

b64encode(s, altchars=None, \*, padded=True, wrapcol=0) Encode the `bytes-like object` *s* using Base64 and return the encoded `bytes`. Optional *altchars* must be a `bytes-like object` of length 2 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. If *padded* is true (default), pad the encoded data with the '=' character to a size multiple of 4. If *padded* is false, do not add the pad characters. If *wrapcol* is non-zero, insert a newline (`b'\n'`) character after at most every *wrapcol* characters. If *wrapcol* is zero (default), do not insert any newlines.

3.15 Added the *padded* and *wrapcol* parameters.

b64decode(s, altchars=None, validate=False, *, padded=True, canonical=False) b64decode(s, altchars=None, validate=True,*, ignorechars, padded=True, canonical=False) Decode the Base64 encoded `bytes-like object` or ASCII string *s* and return the decoded `bytes`. Optional *altchars* must be a `bytes-like object` or ASCII string of length 2 which specifies the alternative alphabet used instead of the `+` and `/` characters. If *padded* is true, the last group of 4 base 64 alphabet characters must be padded with the '=' character. If *padded* is false, padding is neither required nor recognized: the '=' character is not treated as padding but as a non-alphabet character, which means it is silently discarded when *validate* is false, or causes an `~binascii.Error` when *validate* is true unless b'=' is included in *ignorechars*. A `binascii.Error` exception is raised if *s* is incorrectly padded. If *ignorechars* is specified, it should be a `bytes-like object` containing characters to ignore from the input when *validate* is true. If *ignorechars* contains the pad character `'='`, the pad characters presented before the end of the encoded data and the excess pad characters will be ignored. The default value of *validate* is `True` if *ignorechars* is specified, `False` otherwise. If *validate* is false, characters that are neither in the normal base-64 alphabet nor (if *ignorechars* is not specified) the alternative alphabet are discarded prior to the padding check, but the `+` and `/` characters keep their meaning if they are not in *altchars* (they will be discarded in future Python versions). If *validate* is true, these non-alphabet characters in the input result in a `binascii.Error`. If *canonical* is true, non-zero padding bits are rejected. See `binascii.a2b_base64` for details. For more information about the strict base64 check, see `binascii.a2b_base64`

3.15 Added the *canonical*, *ignorechars*, and *padded* parameters.

3.15 Accepting the `+` and `/` characters with an alternative alphabet is now deprecated.

standard_b64encode(s) Encode `bytes-like object` *s* using the standard Base64 alphabet and return the encoded `bytes`.

standard_b64decode(s) Decode `bytes-like object` or ASCII string *s* using the standard Base64 alphabet and return the decoded `bytes`.

urlsafe_b64encode(s, \*, padded=True) 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 `=` if *padded* is true (default).

3.15 Added the *padded* parameter.

urlsafe_b64decode(s, \*, padded=False) 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`.

3.15 Added the *padded* parameter. Padding of input is no longer required by default.

3.15 Accepting the `+` and `/` characters is now deprecated.

b32encode(s, \*, padded=True, wrapcol=0) Encode the `bytes-like object` *s* using Base32 and return the encoded `bytes`. If *padded* is true (default), pad the encoded data with the '=' character to a size multiple of 8. If *padded* is false, do not add the pad characters. If *wrapcol* is non-zero, insert a newline (`b'\n'`) character after at most every *wrapcol* characters. If *wrapcol* is zero (default), do not add any newlines.

3.15 Added the *padded* and *wrapcol* parameters.

b32decode(s, casefold=False, map01=None, \*, padded=True, ignorechars=b'', canonical=False) Decode the Base32 encoded `bytes-like object` or ASCII string *s* and return the decoded `bytes`. Optional *casefold* is a flag specifying whether a lowercase alphabet is acceptable as input. For security purposes, the default is `False`. `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. If *padded* is true, the last group of 8 base 32 alphabet characters must be padded with the '=' character. If *padded* is false, padding is neither required nor recognized: the '=' character is not treated as padding but as a non-alphabet character, which means it raises an `~binascii.Error` unless b'=' is included in *ignorechars*. *ignorechars* should be a `bytes-like object` containing characters to ignore from the input. If *canonical* is true, non-zero padding bits are rejected. See `binascii.a2b_base32` for details. A `binascii.Error` is raised if *s* is incorrectly padded or if there are non-alphabet characters present in the input.

3.15 Added the *canonical*, *ignorechars*, and *padded* parameters.

b32hexencode(s, \*, padded=True, wrapcol=0) Similar to `b32encode` but uses the Extended Hex Alphabet, as defined in `4648`.

3.10

3.15 Added the *padded* and *wrapcol* parameters.

b32hexdecode(s, casefold=False, \*, padded=True, ignorechars=b'', canonical=False) Similar to `b32decode` but uses the Extended Hex Alphabet, as defined in `4648`. This version does not allow the digit 0 (zero) to the letter O (oh) and digit 1 (one) to either the letter I (eye) or letter L (el) mappings, all these characters are included in the Extended Hex Alphabet and are not interchangeable.

3.10

3.15 Added the *canonical*, *ignorechars*, and *padded* parameters.

b16encode(s, \*, wrapcol=0) Encode the `bytes-like object` *s* using Base16 and return the encoded `bytes`. If *wrapcol* is non-zero, insert a newline (`b'\n'`) character after at most every *wrapcol* characters. If *wrapcol* is zero (default), do not add any newlines.

3.15 Added the *wrapcol* parameter.

b16decode(s, casefold=False, \*, ignorechars=b'') Decode the Base16 encoded `bytes-like object` or ASCII string *s* and return the decoded `bytes`. Optional *casefold* is a flag specifying whether a lowercase alphabet is acceptable as input. For security purposes, the default is `False`. *ignorechars* should be a `bytes-like object` containing characters to ignore from the input. A `binascii.Error` is raised if *s* is incorrectly padded or if there are non-alphabet characters present in the input.

3.15 Added the *ignorechars* parameter.

## Base85 Encodings Base85 encoding is a family of algorithms which represent four bytes using five ASCII characters. Originally implemented in the Unix `btoa(1)` utility, a version of it was later adopted by Adobe in the PostScript language and is standardized in PDF 2.0 (ISO 32000-2). This version, in both its `btoa` and PDF variants, is implemented by `a85encode`. A separate version, using a different output character set, was defined as an April Fool's joke in `1924` but is now used by Git and other software. This version is implemented by `b85encode`. Finally, a third version, using yet another output character set designed for safe inclusion in programming language strings, is defined by ZeroMQ and implemented here by `z85encode`. The functions present in this module differ in how they handle the following: - Whether to include and expect enclosing `<~` and `~>` markers. - Whether to fold the input into multiple lines. - The set of ASCII characters used for encoding. - Compact encodings of sequences of spaces and null bytes. - The encoding of zero-padding bytes applied to the input. Refer to the documentation of the individual functions for more information.

a85encode(b, \*, foldspaces=False, wrapcol=0, pad=False, adobe=False) Encode the `bytes-like object` *b* using Ascii85 and return the encoded `bytes`. *foldspaces* is an optional flag that uses the special short sequence 'y' instead of 4 consecutive spaces (ASCII 0x20) as supported by 'btoa'. This feature is not supported by the standard encoding used in PDF. If *wrapcol* is non-zero, insert a newline (`b'\n'`) character after at most every *wrapcol* characters. If *wrapcol* is zero (default), do not insert any newlines. *pad* controls whether zero-padding applied to the end of the input is fully retained in the output encoding, as done by `btoa`, producing an exact multiple of 5 bytes of output. This is not part of the standard encoding used in PDF, as it does not preserve the length of the data. *adobe* controls whether the encoded byte sequence is framed with `<~` and `~>`, as in a PostScript base-85 string literal. Note that while ASCII85Decode streams in PDF documents *must* be terminated with `~>`, they *must not* use a leading `<~`.

3.4

a85decode(b, \*, foldspaces=False, adobe=False, ignorechars=b' tnrv', canonical=False) Decode the Ascii85 encoded `bytes-like object` or ASCII string *b* and return the decoded `bytes`. *foldspaces* is a flag that specifies whether the 'y' short sequence should be accepted as shorthand for 4 consecutive spaces (ASCII 0x20). This feature is not supported by the standard Ascii85 encoding used in PDF and PostScript. *adobe* controls whether the `<~` and `~>` markers are present. While the leading `<~` is not required, the input must end with `~>`, or a `ValueError` is raised. *ignorechars* should be a `bytes-like object` containing characters to ignore from the input. This should only contain whitespace characters, and by default contains all whitespace characters in ASCII. If *canonical* is true, non-canonical encodings are rejected. See `binascii.a2b_ascii85` for details.

3.4

3.15 Added the *canonical* parameter. Single-character final groups are now always rejected as encoding violations.

b85encode(b, pad=False, \*, wrapcol=0) Encode the `bytes-like object` *b* using base85 (as used in e.g. git-style binary diffs) and return the encoded `bytes`. The input is padded with `b'\0'` so its length is a multiple of 4 bytes before encoding. If *pad* is true, all the resulting characters are retained in the output, which will always be a multiple of 5 bytes, and thus the length of the data may not be preserved on decoding. If *wrapcol* is non-zero, insert a newline (`b'\n'`) character after at most every *wrapcol* characters. If *wrapcol* is zero (default), do not add any newlines.

3.4

3.15 Added the *wrapcol* parameter.

b85decode(b, \*, ignorechars=b'', canonical=False) Decode the base85-encoded `bytes-like object` or ASCII string *b* and return the decoded `bytes`. *ignorechars* should be a `bytes-like object` containing characters to ignore from the input. If *canonical* is true, non-canonical encodings are rejected. See `binascii.a2b_base85` for details.

3.4

3.15 Added the *canonical* and *ignorechars* parameters. Single-character final groups are now always rejected as encoding violations.

z85encode(s, pad=False, \*, wrapcol=0) Encode the `bytes-like object` *s* using Z85 (as used in ZeroMQ) and return the encoded `bytes`. The input is padded with `b'\0'` so its length is a multiple of 4 bytes before encoding. If *pad* is true, all the resulting characters are retained in the output, which will always be a multiple of 5 bytes, as required by the ZeroMQ standard. If *wrapcol* is non-zero, insert a newline (`b'\n'`) character after at most every *wrapcol* characters. If *wrapcol* is zero (default), do not add any newlines.

3.13

3.15 The *pad* parameter was added.

3.15 Added the *wrapcol* parameter.

z85decode(s, \*, ignorechars=b'', canonical=False) Decode the Z85-encoded `bytes-like object` or ASCII string *s* and return the decoded `bytes`. *ignorechars* should be a `bytes-like object` containing characters to ignore from the input. If *canonical* is true, non-canonical encodings are rejected. See `binascii.a2b_base85` for details.

3.13

3.15 Added the *canonical* and *ignorechars* parameters. Single-character final groups are now always rejected as encoding violations.

## Legacy Interface

decode(input, output) Decode the contents of the binary *input* file and write the resulting binary data to the *output* file. *input* and *output* must be `file objects `. *input* will be read until `input.readline()` returns an empty bytes object.

decodebytes(s) Decode the `bytes-like object` *s*, which must contain one or more lines of base64 encoded data, and return the decoded `bytes`.

3.1

encode(input, output) Encode the contents of the binary *input* file and write the resulting base64 encoded data to the *output* file. *input* and *output* must be `file objects `. *input* will be read until `input.read()` returns an empty bytes object. `encode` inserts a newline character (`b'\n'`) after every 76 bytes of the output, as well as ensuring that the output always ends with a newline, as per `2045` (MIME).

encodebytes(s) Encode the `bytes-like object` *s*, which can contain arbitrary binary data, and return `bytes` containing the base64-encoded data, with newlines (`b'\n'`) inserted after every 76 bytes of output, and ensuring that there is a trailing newline, as per `2045` (MIME).

3.1

An example usage of the module: > \>\>\> import base64 \>\>\> encoded = base64.b64encode(b'data to be encoded') \>\>\> encoded b'ZGF0YSB0byBiZSBlbmNvZGVk' \>\>\> data = base64.b64decode(encoded) \>\>\> data b'data to be encoded' ## Security Considerations A new security considerations section was added to `4648` (section 12); it's recommended to review the security section for any code deployed to production.

Module `binascii` Support module containing ASCII-to-binary and binary-to-ASCII conversions. `1521` - MIME (Multipurpose Internet Mail Extensions) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies Section 5.2, "Base64 Content-Transfer-Encoding," provides the definition of the base64 encoding. [ISO 32000-2 Portable document format - Part 2: PDF 2.0](https://pdfa.org/resource/iso-32000-2/) Section 7.4.3, "ASCII85Decode Filter," provides the definition of the Ascii85 encoding used in PDF and PostScript, including the output character set and the details of data length preservation using zero-padding and partial output groups. [ZeroMQ RFC 32/Z85](https://rfc.zeromq.org/spec/32/) The "Formal Specification" section provides the character set used in Z85.