Base32 describes a method in which binary data is converted into a string consisting of only 32 different ASCII characters.
Five bytes of 8 bits each (i.e. a total of 40 bits) are broken down into eight 5-bit groups. Each of these groups corresponds to a number between 0 and 31. These numbers are converted into “printable ASCII characters” using a conversion table.
If at the end no more complete 40-bit block can be formed, this block is padded with zero bytes and the 5-bit groups consisting only of fill bits are encoded with = to tell the decoder how many fill bits have been added.