Base64 Encoding Instructions

Base64 encoding requires that 3 8-bit bytes (3*8=24) be converted into 4 6-bit bytes (4*6=24), and then two 0s are added in front of the 6 bits to form an 8-bit word The form of the section. If the remaining characters are less than 3 bytes, fill it with 0, and use'=' for the output character, so 1 or 2'=' may appear at the end of the output text after encoding.

In order to ensure that the output code bits are readable characters, Base64 has developed a code table for unified conversion. The size of the encoding table is 2^6=64, which is the origin of the name of Base64.

Base64 Encoding Table

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