lib/base32.rb in base32-0.2.0 vs lib/base32.rb in base32-0.3.0

@@ -1,26 +1,29 @@
+require 'openssl'
+
+# Module for encoding and decoding in Base32 per RFC 3548
 module Base32
-  TABLE = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
+  TABLE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'.freeze
 
   class Chunk
     def initialize(bytes)
       @bytes = bytes
     end
 
     def decode
       bytes = @bytes.take_while {|c| c != 61} # strip padding
       n = (bytes.length * 5.0 / 8.0).floor
       p = bytes.length < 8 ? 5 - (n * 8) % 5 : 0
-      c = bytes.inject(0) {|m,o| (m << 5) + TABLE.index(o.chr)} >> p
+      c = bytes.inject(0) {|m,o| (m << 5) + Base32.table.index(o.chr)} >> p
       (0..n-1).to_a.reverse.collect {|i| ((c >> i * 8) & 0xff).chr}
     end
-    
+
     def encode
       n = (@bytes.length * 8.0 / 5.0).ceil
       p = n < 8 ? 5 - (@bytes.length * 8) % 5 : 0
       c = @bytes.inject(0) {|m,o| (m << 8) + o} << p
-      [(0..n-1).to_a.reverse.collect {|i| TABLE[(c >> i * 5) & 0x1f].chr},
+      [(0..n-1).to_a.reverse.collect {|i| Base32.table[(c >> i * 5) & 0x1f].chr},
        ("=" * (8-n))]
     end
   end
 
   def self.chunks(str, size)
@@ -30,14 +33,35 @@
       result << Chunk.new(bytes.take(size))
       bytes = bytes.drop(size)
     end
     result
   end
-  
+
   def self.encode(str)
     chunks(str, 5).collect(&:encode).flatten.join
   end
 
   def self.decode(str)
     chunks(str, 8).collect(&:decode).flatten.join
+  end
+
+  def self.random_base32(length=16)
+    random = ''
+    OpenSSL::Random.random_bytes(length).each_byte do |b|
+      random << self.table[b % 32]
+    end
+    random.ljust((length / 8.0).ceil * 8, '=') # add padding
+  end
+
+  def self.table=(table)
+    raise ArgumentError, "Table must have 32 unique characters" unless self.table_valid?(table)
+    @table = table
+  end
+
+  def self.table
+    @table || TABLE
+  end
+
+  def self.table_valid?(table)
+    table.bytes.size == 32 && table.bytes.uniq.size == 32
   end
 end