base32-crockford

A Python module implementing the alternate base32 encoding as described by Douglas Crockford at: http://www.crockford.com/wrmg/base32.html.

He designed the encoding to:

• Be human and machine readable
• Be compact
• Be error resistant
• Be pronounceable

It uses a symbol set of 10 digits and 22 letters, excluding I, L O and U. Decoding is not case sensitive, and 'i' and 'l' are converted to '1' and 'o' is converted to '0'. Encoding uses only upper-case characters.

Hyphens may be present in symbol strings to improve readability, and are removed when decoding.

A check symbol can be appended to a symbol string to detect errors within the string.

Installation

To install, simply run:

pip install base32-crockford

Usage

Basic usage example:

>>> import base32_crockford
>>> base32_crockford.encode(42)
'1A'
>>> base32_crockford.decode('1A')
42
>>> base32_crockford.encode(42, checksum=True)
'1A5'
>>> base32_crockford.decode('1A5', checksum=True)
42
>>> base32_crockford.normalize('La5')
'1A5'

Encode

base32_crockford.encode(n[, checksum=False[, split=0]])

Encode an integer into a symbol string.

When True, optional checksum causes a check symbol to be calculated and appended to the string. This can help detect errors when decoding.

When specified, optional split causes the output string to be divided into clusters of that size separated by hyphens.

Decode

base32_crockford.decode(s[, checksum=False[, strict=False]])

Decode an encoded symbol string.

Optional checksum can be provided as a counterpart to the same argument when encoding. When True, the trailing check symbol is stripped off and validated. If the check symbol validation fails, a ValueError is raised.

When True, optional strict causes a ValueError to be raised if the symbol string requires normalization.

Normalize

base32_crockford.normalize(s[, strict=False])

Normalize an encoded symbol string by applying these transformations:

1. Remove hyphens
2. Replace 'I' and 'L' with '1'
3. Replace 'O' with '0'
4. Convert all characters to uppercase

Ordinarily this function is automatically used when decoding, but can be utilized independently to clean or validate a symbol string. Invalid characters within the normalized string causes a ValueError to be raised.

When True, optional strict causes a ValueError to be raised if the symbol string requires normalization.

Changelog

Version 0.3.0

• Add Python 2.6 support
• Add Python 3.3 and 3.4 support

Version 0.2.0

• Add optional split parameter when encoding

Version 0.1.0

• Initial release