experimental support for site tipping integration via paypal or bitcoin

ext/bitcoin_validator.rb

@@ -0,0 +1,49 @@
+class BitcoinValidator
+  class << self
+    def address_version
+      "00"
+    end
+
+    def p2sh_version
+      "05"
+    end
+
+    def valid_address?(address)
+      hex = decode_base58(address) rescue nil
+      return false unless hex && hex.bytesize == 50
+      return false unless [address_version, p2sh_version].include?(hex[0...2])
+      base58_checksum?(address)
+    end
+
+    def decode_base58(base58_val)
+      s = base58_to_int(base58_val).to_s(16); s = (s.bytesize.odd? ? '0'+s : s)
+      s = '' if s == '00'
+      leading_zero_bytes = (base58_val.match(/^([1]+)/) ? $1 : '').size
+      s = ("00"*leading_zero_bytes) + s  if leading_zero_bytes > 0
+      s
+    end
+
+    def base58_checksum?(base58)
+      hex = decode_base58(base58) rescue nil
+      return false unless hex
+      checksum( hex[0...42] ) == hex[-8..-1]
+    end
+
+    def checksum(hex)
+      b = [hex].pack("H*") # unpack hex
+      Digest::SHA256.hexdigest( Digest::SHA256.digest(b) )[0...8]
+    end
+
+
+    def base58_to_int(base58_val)
+      alpha = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
+      int_val, base = 0, alpha.size
+      base58_val.reverse.each_char.with_index do |char,index|
+        raise ArgumentError, 'Value not a valid Base58 String.' unless char_index = alpha.index(char)
+        int_val += char_index*(base**index)
+      end
+      int_val
+    end
+
+  end
+end