# `binascii` — Converte entre binário e ASCII

The `binascii` module contains a number of methods to convert between binary and various ASCII-encoded binary representations. Normally, you will not use these functions directly but use wrapper modules like `uu`, `base64`, or `binhex` instead. The `binascii` module contains low-level functions written in C for greater speed that are used by the higher-level modules.

Nota

Funções `a2b_*` aceitam strings Unicode contendo apenas caracteres ASCII. Outras funções aceitam apenas objetos bytes ou similares (como `bytes`, `bytearray` e outros objetos que suportam o protocolo buffer).

Alterado na versão 3.3: Strings unicode exclusivamente ASCII agora são aceitas pelas funções `a2b_*`.

O módulo `binascii` define as seguintes funções:

`binascii.``a2b_uu`(string)

  Converte uma única linha de dados uuencoded de volta para binário e retorna os dados binários. As linhas normalmente contêm 45 bytes (binários), exceto a última linha. Os dados da linha podem ser seguidos por espaços em branco.

`binascii.``b2a_uu`(data, *, backtick=False)

  Converte dados binários para uma linha de caracteres ASCII, o valor de retorno é a linha convertida, incluindo um caractere de nova linha. O comprimento de data deve ser no máximo 45. Se backtick for true, zeros são representados por `'`'` em vez de espaços.

  Alterado na versão 3.7: Adicionado o parâmetro backtick.

`binascii.``a2b_base64`(string)

  Converte um bloco de dados base64 de volta para binário e retorna os dados binários. Mais de uma linha pode ser passada por vez.

`binascii.``b2a_base64`(data, *, newline=True)

  Converte dados binários para uma linha de caracteres ASCII em codificação base64. O valor de retorno é a linha convertida, incluindo um caractere de nova linha se newline for verdadeiro. A saída desta função está em conformidade com RFC 3548.

  Alterado na versão 3.6: Adicionado o parâmetro newline.

`binascii.``a2b_qp`(data, header=False)

  Convert a block of quoted-printable data back to binary and return the binary data. More than one line may be passed at a time. If the optional argument header is present and true, underscores will be decoded as spaces.

`binascii.``b2a_qp`(data, quotetabs=False, istext=True, header=False)

  Convert binary data to a line(s) of ASCII characters in quoted-printable encoding. The return value is the converted line(s). If the optional argument quotetabs is present and true, all tabs and spaces will be encoded. If the optional argument istext is present and true, newlines are not encoded but trailing whitespace will be encoded. If the optional argument header is present and true, spaces will be encoded as underscores per RFC 1522. If the optional argument header is present and false, newline characters will be encoded as well; otherwise linefeed conversion might corrupt the binary data stream.

`binascii.``a2b_hqx`(string)

  Convert binhex4 formatted ASCII data to binary, without doing RLE-decompression. The string should contain a complete number of binary bytes, or (in case of the last portion of the binhex4 data) have the remaining bits zero.

  Obsoleto desde a versão 3.9.

`binascii.``rledecode_hqx`(data)

  Perform RLE-decompression on the data, as per the binhex4 standard. The algorithm uses `0x90` after a byte as a repeat indicator, followed by a count. A count of `0` specifies a byte value of `0x90`. The routine returns the decompressed data, unless data input data ends in an orphaned repeat indicator, in which case the `Incomplete` exception is raised.

  Alterado na versão 3.2: Accept only bytestring or bytearray objects as input.

  Obsoleto desde a versão 3.9.

`binascii.``rlecode_hqx`(data)

  Perform binhex4 style RLE-compression on data and return the result.

  Obsoleto desde a versão 3.9.

`binascii.``b2a_hqx`(data)

  Perform hexbin4 binary-to-ASCII translation and return the resulting string. The argument should already be RLE-coded, and have a length divisible by 3 (except possibly the last fragment).

  Obsoleto desde a versão 3.9.

`binascii.``crc_hqx`(data, value)

  Compute a 16-bit CRC value of data, starting with value as the initial CRC, and return the result. This uses the CRC-CCITT polynomial x16 + x12 + x5 + 1, often represented as 0x1021. This CRC is used in the binhex4 format.

`binascii.``crc32`(data[, value])

  Compute CRC-32, the unsigned 32-bit checksum of data, starting with an initial CRC of value. The default initial CRC is zero. The algorithm is consistent with the ZIP file checksum. Since the algorithm is designed for use as a checksum algorithm, it is not suitable for use as a general hash algorithm. Use as follows:

      print(binascii.crc32(b"hello world"))
      # Or, in two pieces:
      crc = binascii.crc32(b"hello")
      crc = binascii.crc32(b" world", crc)
      print('crc32 = {:#010x}'.format(crc))

  Alterado na versão 3.0: The result is always unsigned. To generate the same numeric value when using Python 2 or earlier, use `crc32(data) & 0xffffffff`.

`binascii.``b2a_hex`(data[, sep[, bytes_per_sep=1]])
`binascii.``hexlify`(data[, sep[, bytes_per_sep=1]])

  Return the hexadecimal representation of the binary data. Every byte of data is converted into the corresponding 2-digit hex representation. The returned bytes object is therefore twice as long as the length of data.

  Similar functionality (but returning a text string) is also conveniently accessible using the `bytes.hex()` method.

  If sep is specified, it must be a single character str or bytes object. It will be inserted in the output after every bytes_per_sep input bytes. Separator placement is counted from the right end of the output by default, if you wish to count from the left, supply a negative bytes_per_sep value.

      >>> import binascii
      >>> binascii.b2a_hex(b'\xb9\x01\xef')
      b'b901ef'
      >>> binascii.hexlify(b'\xb9\x01\xef', '-')
      b'b9-01-ef'
      >>> binascii.b2a_hex(b'\xb9\x01\xef', b'_', 2)
      b'b9_01ef'
      >>> binascii.b2a_hex(b'\xb9\x01\xef', b' ', -2)
      b'b901 ef'

  Alterado na versão 3.8: The sep and bytes_per_sep parameters were added.

`binascii.``a2b_hex`(hexstr)
`binascii.``unhexlify`(hexstr)

  Return the binary data represented by the hexadecimal string hexstr. This function is the inverse of `b2a_hex()`. hexstr must contain an even number of hexadecimal digits (which can be upper or lower case), otherwise an `Error` exception is raised.

  Similar functionality (accepting only text string arguments, but more liberal towards whitespace) is also accessible using the `bytes.fromhex()` class method.

exception `binascii.``Error`

  Exception raised on errors. These are usually programming errors.

exception `binascii.``Incomplete`

  Exception raised on incomplete data. These are usually not programming errors, but may be handled by reading a little more data and trying again.

Ver também

Módulo `base64`

  Support for RFC compliant base64-style encoding in base 16, 32, 64, and 85.

Module `binhex`

  Support for the binhex format used on the Macintosh.

Module `uu`

  Support for UU encoding used on Unix.

Módulo `quopri`

  Support for quoted-printable encoding used in MIME email messages.