Base 58 Encoding

Base 58 Encoding

Base 58 encoding is used for encoding addresses.

Address = Base58Encode(RIPEMD160(SHA-256(public key))

The public key is expresses as an encoded point.

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

The algorithm for encoding is

   code_string = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
   x = convert_bytes_to_big_integer(hash_result)
   
   output_string = ""
   
   while(x > 0) 
       {
           (x, remainder) = divide(x, 58)
           output_string.append(output_string[remainder])
       }
   
   repeat(number_of_leading_zeros_in_hash)
       {
       output_string.append(output_string[0]);
       }
   
   output_string.reverse();

Source

https://github.com/bitcoin/bitcoin/blob/master/src/base58.h