What does base-64 mean?

General Information ID:    INFO992    Updated:    07/27/2016

Description

Base64 is a method of encoding binary data as ASCII text. This is necessary for sending files via Internet email, which can only handle 7-bit ASCII text.

Base64 is the industry standard format for SSL certificate content. The most common web servers will generate a certificate signing requests as well as accept SSL certificates in base-64 format.

The size of the certificate content will depend on the encryption strength of the certificate.

Here is an example of a base64-encoded certificate.

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

 

The base64 alphabet

The base64 alphabet is shown in the below table.  Whenever the value of a six-bit group matches one of the values in the Value columns, that value is replaced by the seven-bit ASCII value of the corresponding character shown in the Char column to the right of the Value column.

Value Char Value Char Value Char Value Char
0 A 17 R 34 i 51 z
1 B 18 S 35 j 52 0
2 C 19 T 36 k 53 1
3 D 20 U 37 l 54 2
4 E 21 V 38 m 55 3
5 F 22 W 39 n 56 4
6 G 23 X 40 o 57 5
7 H 24 Y 41 p 58 6
8 I 25 Z 42 q 59 7
9 J 26 a 43 r 60 8
10 K 27 b 44 s 61 9
11 L 28 c 45 t 62 +
12 M 29 d 46 u 63 /
13 N 30 e 47 v pad =
14 O 31 f 48 w    
15 P 32 g 49 x    
16 Q 33 h 50 y    

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