Base32 Characters, Alphabet, Table, and Padding Explained
In this article we will learn in detail about the Base32 characters, or alphabet, in table form. We will show the differences between the characters of each Base32 variation and even explain the meaning and function of padding.
What is Base32?
Base32 is fundamentally a binary-to-text encoding technique that enables the representation of binary data in a sanely readable format. It use a set of 32 characters to accomplish this. In contrast to raw binary data, which can include unusual or non-printable characters that can cause problems during transmission or storage.
Base32 Breakdown:
Binary Shrinkwrap: Takes binary data (like codes) and turns it into a shorter text format using letters (A-Z) and numbers (2-7).
URL Friendly: Avoids symbols that cause problems in web addresses, making it useful for embedding data in URLs.
Not Encryption: Anyone can decode the Base32 text back to the original data. Think of it as a different language, not a secret message.
Base32 Character Set
The character set is the key to Base32. This encoding technique employs a limited number of 32 characters, which include uppercase letters A through Z and numerals 2–7. This character set was carefully constructed to eliminate ambiguity and ensure that encoded data may be correctly decoded.
Characters in Base32 encoding are classified into distinct categories based on their indices within the character set. These are some of the categories:
Uppercase Letters (Indices 0-25): A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z
Numbers (Indices 26-31): 2, 3, 4, 5, 6, 7
Base32 Table
Below you can see a table of Base32 characters. This table shows the mapping between the original binary values and their corresponding Base32 characters. Each group of 5 binary bits (representing a tiny chunk of data) gets converted into a single Base32 character using this table.
Binary
Decimal
Base32
00000
0
A
00001
1
B
00010
2
C
00011
3
D
00100
4
E
00101
5
F
00110
6
G
00111
7
H
01000
8
I
01001
9
J
01010
10
K
01011
11
L
01100
12
M
01101
13
N
01110
14
O
01111
15
P
10000
16
Q
10001
17
R
10010
18
S
10011
19
T
10100
20
U
10101
21
V
10110
22
W
10111
23
X
11000
24
Y
11001
25
Z
11010
26
2
11011
27
3
11100
28
4
11101
29
5
11110
30
6
11111
31
7
Base32 Padding
Padding in the context of Base32 refers to the addition of extra characters, usually “=” (equals signs), at the end of the encoded data to ensure that the encoded data’s length is a multiple of 8 characters. In Base32, each character represents 5 bits of data, so it’s common to have leftover bits when encoding binary data that is not an exact multiple of 5 bits in length. Padding is used to fill in these leftover bits, making the encoded data’s length a multiple of 40 bits (5 bits per character times 8 characters).
Let’s break down how padding works in Base32 encoding:
If the last 5-byte block contains 1 byte of input data, add 4 zero bytes. Then, encode it as a regular block and replace the last 6 characters with 6 equal signs (======).
If the last 5-byte block holds 2 bytes of input data, add 3 zero bytes. After encoding it as a standard block, change the last 4 characters to 4 equal signs (====).
If the last 5-byte block includes 3 bytes of input data, add 2 zero bytes. Encode it as a regular block and replace the last 3 characters with 3 equal signs (===).
If the last 5-byte block has 4 bytes of input data, add 1 zero byte. After encoding it as a normal block, replace the last 1 character with 1 equal sign (=).
This is why padding is necessary:
Data Length Consistency: Without padding, the length of Base32-encoded data may not be consistent, making it challenging to determine the original data’s size during decoding. Padding ensures that the encoded data always has a length that is a multiple of 40 bits, simplifying the decoding process.
Alignment: Padding aligns the encoded data to fixed boundaries, making it easier to work with and ensuring that the data can be decoded correctly.
Error Detection: By including padding characters, Base32 encoding can incorporate basic error-checking functionality. If the decoded data does not end with the expected padding characters, it may indicate a data integrity issue.
Differences Between Base32, Z-Base32, Base32Hex and Crockford’s Base32 Character Sets
The table below shows the differences between the character sets of each Base32 variant. The table shows the Base32, Z-Base32, Base32Hex and Crockford’s Base32 encoding methods.
