diff --git a/src/mame/machine/segacrp2_device.cpp b/src/mame/machine/segacrp2_device.cpp
index b07f735445d..16f3ec0daa7 100644
--- a/src/mame/machine/segacrp2_device.cpp
+++ b/src/mame/machine/segacrp2_device.cpp
@@ -27,7 +27,7 @@
   315-5162      4D Warriors &          used I'm Sorry for k.p.a.
                 Rafflesia &
                 Wonder Boy (set 4)
-  315-5176      Wonder Boy (system 2 hardware, set 2) NOT DECRYPTED
+  315-5176      Wonder Boy (system 2 hardware, set 2)
   315-5177      Astro Flash &
                 Wonder Boy (set 1)
   315-5178      Wonder Boy (set 2)     unencrypted version available
@@ -166,8 +166,45 @@ sega_315_5176_device::sega_315_5176_device(const machine_config &mconfig, const
 
 void sega_315_5176_device::decrypt()
 {
-	// 315-5176
-	// TODO!
+	static const uint8_t xor_table[128] =
+	{
+		0x44, 0x01, 0x51, 0x15, 0x40, 0x04, 0x54, 0x11, 0x45, 0x00, 0x50, 0x14,
+		0x41, 0x05, 0x55, 0x10, 0x44, 0x01, 0x51, 0x15, 0x40, 0x04, 0x54, 0x11,
+		0x45, 0x00, 0x50, 0x14, 0x41, 0x05, 0x55, 0x10, 0x44, 0x01, 0x51, 0x15,
+		0x40, 0x04, 0x54, 0x11, 0x45, 0x00, 0x50, 0x14, 0x41, 0x05, 0x55, 0x10,
+		0x44, 0x01, 0x51, 0x15, 0x40, 0x04, 0x54, 0x11, 0x45, 0x00, 0x50, 0x14,
+		0x41, 0x05, 0x55, 0x10,
+
+		0x44, 0x01, 0x51, 0x15, 0x40, 0x04, 0x54, 0x11, 0x45, 0x00, 0x50, 0x14,
+		0x41, 0x05, 0x55, 0x10, 0x44, 0x01, 0x51, 0x15, 0x40, 0x04, 0x54, 0x11,
+		0x45, 0x00, 0x50, 0x14, 0x41, 0x05, 0x55, 0x10, 0x44, 0x01, 0x51, 0x15,
+		0x40, 0x04, 0x54, 0x11, 0x45, 0x00, 0x50, 0x14, 0x41, 0x05, 0x55, 0x10,
+		0x44, 0x01, 0x51, 0x15, 0x40, 0x04, 0x54, 0x11, 0x45, 0x00, 0x50, 0x14,
+		0x41, 0x05, 0x55, 0x10,
+	};
+
+	static const int swap_table[128] =
+	{
+		0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01,
+		0x01, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x03,
+		0x03, 0x03, 0x03, 0x03, 0x04, 0x04, 0x04, 0x04,
+		0x04, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x06,
+		0x06, 0x06, 0x06, 0x06, 0x07, 0x07, 0x07, 0x07,
+		0x07, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x09,
+		0x09, 0x09, 0x09, 0x09, 0x0a, 0x0a, 0x0a, 0x0a,
+		0x0a, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0c,
+
+		0x08, 0x08, 0x08, 0x08, 0x09, 0x09, 0x09, 0x09,
+		0x09, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0a, 0x0b,
+		0x0b, 0x0b, 0x0b, 0x0b, 0x0c, 0x0c, 0x0c, 0x0c,
+		0x0c, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 0x0d, 0x0e,
+		0x0e, 0x0e, 0x0e, 0x0e, 0x0f, 0x0f, 0x0f, 0x0f,
+		0x0f, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x11,
+		0x11, 0x11, 0x11, 0x11, 0x12, 0x12, 0x12, 0x12,
+		0x12, 0x13, 0x13, 0x13, 0x13, 0x13, 0x13, 0x14,
+	};
+
+	decode(memregion(tag())->base(), m_decrypted, xor_table, swap_table);
 }