In this step, a check character is added at the end of the text to validate it and to protect it against accidental errors. The check character is computed using the Luhn mod N algorithm (see https://en.wikipedia.org/wiki/Luhn_mod_N_algorithm).
Example: Lod72
|
character index |
character |
base57 value |
factor |
addend |
sum digits |
sum |
|
4 |
2 |
1 |
2 |
2 |
2 |
2 |
|
3 |
7 |
6 |
1 |
6 |
6 |
8 |
|
2 |
d |
36 |
2 |
72 |
16 |
24 |
|
1 |
o |
46 |
1 |
46 |
46 |
70 |
|
0 |
L |
19 |
2 |
38 |
38 |
108 |
sum = 108
Check character value = ( 57 - ( 108 mod 57 ) ) mod 57 = 6
Check character = 7
Result = Lod727