# `base64` — Base16, Base32, Base64, Base85 Data Encodings

Código fuente: Lib/base64.py

This module provides functions for encoding binary data to printable ASCII characters and decoding such encodings back to binary data. This includes the encodings specified in RFC 4648 (Base64, Base32 and Base16), the Base85 encoding specified in PDF 2.0, and non-standard variants of Base85 used elsewhere.

Hay dos interfaces proporcionadas por este módulo. La interfaz moderna admite la codificación de objetos similares a bytes a ASCII `bytes` y la decodificación de objetos similares a bytes o cadenas que contienen ASCII a `bytes`. Se admiten los dos alfabetos base 64 definidos en RFC 4648 (normal y seguro para URL y sistema de archivos).

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.

Distinto en la versión 3.3: Las cadenas de caracteres Unicode de solo ASCII ahora son aceptadas por las funciones de decodificación de la interfaz moderna.

Distinto en la versión 3.4: Cualquier objeto similar a bytes ahora son aceptados por todas las funciones de codificación y decodificación en este módulo. Ascii85/Base85 soporte agregado.

## RFC 4648 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.

base64.b64encode(s, altchars=None, *, padded=True, wrapcol=0)

  Codifica el objeto similar a bytes s utilizando Base64 y retorna los `bytes` codificados.

  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.

  Distinto en la versión 3.15: Added the padded and wrapcol parameters.

base64.b64decode(s, altchars=None, validate=False, *, padded=True, canonical=False)
base64.b64decode(s, altchars=None, validate=True, *, ignorechars, padded=True, canonical=False)

  Decodifica el objeto similar a bytes codificado en Base64 o cadena de caracteres ASCII s y retorna los `bytes` decodificados.

  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 `Error` when validate is true unless b”=” is included in ignorechars.

  Una excepción `binascii.Error` se lanza si s está incorrectamente rellenado (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.

  Para más información sobre la verificación estricta de base64, véase `binascii.a2b_base64()`

  Distinto en la versión 3.15: Added the canonical, ignorechars, and padded parameters.

  Obsoleto desde la versión 3.15: Accepting the `+` and `/` characters with an alternative alphabet is now deprecated.

base64.standard_b64encode(s)

  Codifica el objeto similar a bytes s usando el alfabeto estándar Base64 y retorna los `bytes` codificados.

base64.standard_b64decode(s)

  Decodifica un bytes-like object o cadena de caracteres ASCII s utilizando el alfabeto estándar Base64 y retorna los `bytes` decodificados.

base64.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).

  Distinto en la versión 3.15: Added the padded parameter.

base64.urlsafe_b64decode(s, *, padded=False)

  Decodifica objeto similar a bytes o cadena de caracteres ASCII s utilizando el alfabeto seguro para URL y sistema de archivos, que sustituye `-` en lugar de `+` y `_` en lugar de `/` en el alfabeto estándar de Base64, y retorna los `bytes` decodificados.

  Distinto en la versión 3.15: Added the padded parameter. Padding of input is no longer required by default.

  Obsoleto desde la versión 3.15: Accepting the `+` and `/` characters is now deprecated.

base64.b32encode(s, *, padded=True, wrapcol=0)

  Codifica el objeto similar a bytes s utilizando Base32 y retorna los `bytes` codificados.

  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.

  Distinto en la versión 3.15: Added the padded and wrapcol parameters.

base64.b32decode(s, casefold=False, map01=None, *, padded=True, ignorechars=b'', canonical=False)

  Decodifica el objeto similar a bytes codificado en Base32 o cadena de caracteres ASCII s y retorna los `bytes` decodificados.

  El opcional casefold es un flag que especifica si un alfabeto en minúscula es aceptable como entrada. Por motivos de seguridad, el valor predeterminado es `Falso`.

  RFC 4648 permite la asignación opcional del dígito 0 (cero) a la letra O (oh), y la asignación opcional del dígito 1 (uno) a la letra I (ojo) o la letra L (el) . El argumento opcional map01 cuando no es `None`, especifica la letra a la cual el dígito 1 debería mapearse(cuando map01 no es `None`, el dígito 0 siempre se asigna a la letra O). Por motivos de seguridad, el valor predeterminado es `None`, por lo que 0 y 1 no están permitidos en la entrada.

  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 `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.

  Una `binascii.Error` se lanza si s está incorrectamente rellenado (padded) o si hay caracteres no alfabéticos presentes en la entrada.

  Distinto en la versión 3.15: Added the canonical, ignorechars, and padded parameters.

base64.b32hexencode(s, *, padded=True, wrapcol=0)

  Similar a `b32encode()` pero usa el Alfabeto Hexagonal Extendido, como se define en RFC 4648.

  Added in version 3.10.

  Distinto en la versión 3.15: Added the padded and wrapcol parameters.

base64.b32hexdecode(s, casefold=False, *, padded=True, ignorechars=b'', canonical=False)

  Similar a `b32decode()` pero usa el Alfabeto Hexagonal Extendido, como se define en RFC 4648.

  Esta versión no permite el dígito 0 (cero) a la letra O (oh) y el dígito 1 (uno) a las asignaciones de la letra I (ojo) o la letra L (el), todos estos caracteres están incluidos en el Alfabeto Hexagonal Extendido y no son intercambiables.

  Added in version 3.10.

  Distinto en la versión 3.15: Added the canonical, ignorechars, and padded parameters.

base64.b16encode(s, *, wrapcol=0)

  Codifica el objeto similar a bytes s utilizando Base16 y retorna los `bytes` codificados.

  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.

  Distinto en la versión 3.15: Added the wrapcol parameter.

base64.b16decode(s, casefold=False, *, ignorechars=b'')

  Decodifica el objeto similar a bytes codificado en Base16 o cadena de caracteres ASCII s y retorna los `bytes` decodificados.

  El opcional casefold es un flag que especifica si un alfabeto en minúscula es aceptable como entrada. Por motivos de seguridad, el valor predeterminado es `Falso`.

  ignorechars should be a bytes-like object containing characters to ignore from the input.

  Una `binascii.Error` se lanza si s está incorrectamente rellenado (padded) o si hay caracteres no alfabéticos presentes en la entrada.

  Distinto en la versión 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 RFC 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.

base64.a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False)

  Codifica el objeto similar a bytes b utilizando Ascii85 y retorna los `bytes` codificados.

  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 `<~`.

  Added in version 3.4.

base64.a85decode(b, *, foldspaces=False, adobe=False, ignorechars=b' \t\n\r\x0b', canonical=False)

  Decodifica el objeto similar a bytes codificado en Ascii85 o cadena de caracteres ASCII b y retorna los `bytes` decodificados.

  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.

  Added in version 3.4.

  Distinto en la versión 3.15: Added the canonical parameter. Single-character final groups are now always rejected as encoding violations.

base64.b85encode(b, pad=False, *, wrapcol=0)

  Codifica el objeto similar a bytes b utilizando base85 (como se usa en por ejemplo, diferencias binarias de estilo git) y retorna los `bytes` codificados.

  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.

  Added in version 3.4.

  Distinto en la versión 3.15: Added the wrapcol parameter.

base64.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.

  Added in version 3.4.

  Distinto en la versión 3.15: Added the canonical and ignorechars parameters. Single-character final groups are now always rejected as encoding violations.

base64.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.

  Added in version 3.13.

  Distinto en la versión 3.15: The pad parameter was added.

  Distinto en la versión 3.15: Added the wrapcol parameter.

base64.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.

  Added in version 3.13.

  Distinto en la versión 3.15: Added the canonical and ignorechars parameters. Single-character final groups are now always rejected as encoding violations.

## Legacy Interface

base64.decode(input, output)

  Decodifica el contenido del archivo binario input y escribe los datos binarios resultantes en el archivo output. input y output deben ser objetos archivo. input se leerá hasta que `input.readline()` retorne un objeto de bytes vacío.

base64.decodebytes(s)

  Decodifica el objeto similar a bytes s, que debe contener una o más líneas de datos codificados en base64, y retornará los `bytes` decodificados.

  Added in version 3.1.

base64.encode(input, output)

  Codifica el contenido del archivo binario input y escribe los datos codificados en base64 resultantes en el archivo output. input y output deben ser objetos archivos. input se leerá hasta que `input.read()` retorna un objeto de bytes vacío. `encode()` inserta un carácter de nueva línea (`b'\n'`) después de cada 76 bytes de la salida, además de garantizar que la salida siempre termine con una nueva línea, según RFC 2045 (MIME).

base64.encodebytes(s)

  Codifica el objeto similar a bytes s, que puede contener datos binarios arbitrarios, y retorna `bytes` que contienen los datos codificados en base64, con líneas nuevas (`b'\n'`) insertado después de cada 76 bytes de salida, y asegurando que haya una nueva línea final, según RFC 2045 (MIME).

  Added in version 3.1.

Un ejemplo de uso del módulo:

    >>> import base64
    >>> encoded = base64.b64encode(b'data to be encoded')
    >>> encoded
    b'ZGF0YSB0byBiZSBlbmNvZGVk'
    >>> data = base64.b64decode(encoded)
    >>> data
    b'data to be encoded'

## Consideraciones de Seguridad

Se agregó una nueva sección de consideraciones de seguridad a RFC 4648 (sección 12); se recomienda revisar la sección de seguridad para cualquier código implementado en producción.

Ver también

Módulo `binascii`

  Módulo de soporte que contiene conversiones de ASCII a binario y binario a ASCII.

RFC 1521 - MIME (Extensiones multipropósito de correo de Internet) Parte uno: Mecanismos para especificar y describir el formato de los cuerpos de mensajes de Internet

  La Sección 5.2, «Codificación de transferencia de contenido Base64», proporciona la definición de la codificación base64.

ISO 32000-2 Portable document format - Part 2: PDF 2.0

  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

  The «Formal Specification» section provides the character set used in Z85.