Compared to similar Base32 encodings like RFC 4648, Crockford’s encoding has a few desirable characteristics which make it especially appealing for user-facing use:

Potentially ambiguous characters, like i, I, l, and L are treated as synonyms.
The digits 0 through F have the same value as their hexadecimal counterparts.
The letter U is invalid, lowering the surface area for obscene encodings.

This library deviates from Crockford’s encoding by encoding strings as lower-case by default. Hyphens are also disallowed as spacing and check characters are unimplemented, although this is a shortcoming of the implementation.

1API🔗 i

(require base32 ) package: base32

1.1Encoding and decoding byte-strings🔗 i

procedure
( base32? x)→boolean?
x:any/c

Determines whether or not a value is a valid Base32 encoding.

procedure
( base32-decode-bytes b32)→bytes?
b32:base32?

Encodes bs as a base32 encoded string.

procedure
( base32-encode-bytes bs)→base32?
bs:bytes?

Encodes bs as a base32 encoded string.

1.2Encoding and decoding ports🔗 i

procedure
( base32-decode in[#:close?close?])→input-port?
in:input-port?
close?:boolean? =#t

Create a new input port that reads bytes from in after decoding them. If in is not base32 encoded, read will raise an exn:fail:contract upon encountering an invalid character.

If close? is #t, in will be closed once eof is reached.

procedure
( base32-encode in[#:close?close?])→input-port?
in:input-port?
close?:boolean? =#t

Create a new input port that reads base64-encoded bytes from in.

If close? is #t, in will be closed once eof is reached.

1.3Comparing base32 strings🔗 i

Because some characters are synonymous, two Base32 encodings may be representationally equivalent but not structurally equivalent.

Examples:

> (define-values (xy)
(values "ABC0123"
"abcoi23"))
> (equal? xy)

#f
> (base32=? xy)

#t
> (string<? xy)

#t
> (base32<? xy)

#f

procedure
( base32=? xy)→boolean?
x:base32?
y:base32?

Determine if two base32 strings are equivalent after normalizing synonymous characters.

procedure
( base32<? xy)→boolean?
x:base32?
y:base32?

Determine if two base32 strings are ordered lexicographically after normalizing synonymous characters.

2Conversion table🔗 i

The following table shows the decimal value for each valid base32 character. When encoding, this library always chooses the first base32 representation in the table below.

base 10

base 32

0 o O =

1 i I l L

a A

b B

c C

d D

e E

f F

g G

h H

j J

k K

m M

n N

p P

q Q

r R

s S

t T

v V

w W

x X

y Y

z Z

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