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base32hex.3tcl

---

NAME

base32::hex - base32 extended hex encoding

SYNOPSIS

package require Tcl 8.4

package require base32::core ?0.1?

package require base32::hex ?0.1?

::base32::hex::encode string

::base32::hex::decode estring

---

DESCRIPTION

This package provides commands for encoding and decoding of strings into and out of the extended hex base32 encoding as specified in the RFC 3548bis draft.

API

::base32::hex::encode string

This command encodes the given string in extended hex base32 and returns the encoded string as its result. The result may be padded with the character = to signal a partial encoding at the end of the input string.

::base32::hex::decode estring

This commands takes the estring and decodes it under the assumption that it is a valid extended hex base32 encoded string. The result of the decoding is returned as the result of the command.

Note that while the encoder will generate only uppercase characters this decoder accepts input in lowercase as well.

The command will always throw an error whenever encountering conditions which signal some type of bogus input, namely if

[1]

the input contains characters which are not valid output of a extended hex base32 encoder,

[2]

the length of the input is not a multiple of eight,

[3]

padding appears not at the end of input, but in the middle,

[4]

the padding has not of length six, four, three, or one characters,

Code map

The code map used to convert 5-bit sequences is shown below, with the numeric id of the bit sequences to the left and the character used to encode it to the right. The important feature of the extended hex mapping is that the first 16 codes map to the digits and hex characters.

 
         0 0    9 9        18 I   27 R
         1 1   10 A        19 J   28 S
         2 2   11 B        20 K   29 T
         3 3   12 C        21 L   30 U
         4 4   13 D        22 M   31 V
         5 5   14 E        23 N
         6 6   15 F        24 O
         7 7        16 G   25 P
         8 8        17 H   26 Q
 
 

KEYWORDS

base32, hex, rfc3548

COPYRIGHT

 Copyright (c) Public domain