module SecureRandom

def self.base58(n = 16)

p SecureRandom.base58(24) # => "77TMHrHJFvFDwodq8w7Ev2m7"
p SecureRandom.base58 # => "4kUgL2pdQMSCQtjE"

The result may contain alphanumeric characters except 0, O, I, and l.

If _n_ is not specified or is +nil+, 16 is assumed. It may be larger in the future.

The argument _n_ specifies the length of the random string to be generated.

SecureRandom.base58 generates a random base58 string. 
def self.base58(n = 16)
  SecureRandom.random_bytes(n).unpack("C*").map do |byte|
    idx = byte % 64
    idx = SecureRandom.random_number(58) if idx >= 58
    BASE58_ALPHABET[idx]
  end.join
end