// license:BSD-3-Clause // copyright-holders:Paul Leaman, Andreas Naive, Nicola Salmoria,Charles MacDonald /****************************************************************************** CPS-2 Encryption All credit goes to Andreas Naive for breaking the encryption algorithm. Code by Nicola Salmoria. Thanks to Charles MacDonald and Razoola for extracting the data from the hardware. The encryption only affects opcodes, not data. It consists of two 4-round Feistel networks (FN) and involves both the 16-bit opcode and the low 16 bits of the address. Let be: E = 16-bit ciphertext A = 16-bit address K = 64-bit key D = 16-bit plaintext y = FN1(x,k) = function describing the first Feistel network (x,y = 16 bit, k = 64 bit) y = FN2(x,k) = function describing the second Feistel network (x,y = 16 bit, k = 64 bit) y = EX(x) = fixed function that expands the 16-bit x to the 64-bit y Then the cipher can be described as: D = FN2( E, K XOR EX( FN1(A, K ) ) ) Each round of the Feistel networks consists of four substitution boxes. The boxes have 6 inputs and 2 outputs. Usually the input is the XOR of a data bit and a key bit, however in some cases only the key is used. (TODO-notes about accuracy of s-boxes) The s-boxes were chosen in order to use an empty key (all FF) for the dead board. Also, the hardware has different watchdog opcodes and address range (see below) which are stored in the battery backed RAM. There doesn't appear to be any relation between those and the 64-bit encryption key, so they probably use an additional 64 bits of battery-backed RAM. First FN: B(0 1 3 5 8 9 11 12) A(10 4 6 7 2 13 15 14) L0 R0 | | XOR<-----------[F1]<------------| | | R1 L1 | | |------------>[F2]----------->XOR | | L2 R2 | | XOR<-----------[F3]<------------| | | R3 L3 | | |------------>[F4]----------->XOR | | L4 R4 (10 4 6 7 2 13 15 14) (0 1 3 5 8 9 11 12) Second FN: B(3 5 9 10 8 15 12 11) A(6 0 2 13 1 4 14 7) L0 R0 | | XOR<-----------[F1]<------------| | | R1 L1 | | |------------>[F2]----------->XOR | | L2 R2 | | XOR<-----------[F3]<------------| | | R3 L3 | | |------------>[F4]----------->XOR | | L4 R4 (6 0 2 13 1 4 14 7) (3 5 9 10 8 15 12 11) ****************************************************************************** Some Encryption notes. ---------------------- Address range. The encryption does _not_ cover the entire address space. The range covered differs per game. Encryption Watchdog. The CPS2 system has a watchdog system that will disable the decryption of data if the watchdog isn't triggered at least once every few seconds. The trigger varies from game to game (some games do use the same) and is basically a 68000 opcode/s instruction. The instruction is the same for all regions of the game. The watchdog instructions are listed alongside the decryption keys. *******************************************************************************/ #include "emu.h" #include "cpu/m68000/m68000.h" #include "ui/uimain.h" #include "includes/cps1.h" /******************************************************************************/ static const int fn1_groupA[8] = { 10, 4, 6, 7, 2, 13, 15, 14 }; static const int fn1_groupB[8] = { 0, 1, 3, 5, 8, 9, 11, 12 }; static const int fn2_groupA[8] = { 6, 0, 2, 13, 1, 4, 14, 7 }; static const int fn2_groupB[8] = { 3, 5, 9, 10, 8, 15, 12, 11 }; /******************************************************************************/ // The order of the input and output bits in the s-boxes is arbitrary. // Each s-box can be XORed with an arbitrary vale in range 0-3 (but the same value // must be used for the corresponding output bits in f1 and f3 or in f2 and f4) struct sbox { const uint8_t table[64]; const int inputs[6]; // positions of the inputs bits, -1 means no input except from key const int outputs[2]; // positions of the output bits }; // the above struct better defines how the hardware works, however // to speed up the decryption at run time we convert it to the // following one struct optimised_sbox { uint8_t input_lookup[256]; uint8_t output[64]; }; static const struct sbox fn1_r1_boxes[4] = { { // subkey bits 0- 5 { 0,2,2,0,1,0,1,1,3,2,0,3,0,3,1,2,1,1,1,2,1,3,2,2,2,3,3,2,1,1,1,2, 2,2,0,0,3,1,3,1,1,1,3,0,0,1,0,0,1,2,2,1,2,3,2,2,2,3,1,3,2,0,1,3, }, { 3, 4, 5, 6, -1, -1 }, { 3, 6 } }, { // subkey bits 6-11 { 3,0,2,2,2,1,1,1,1,2,1,0,0,0,2,3,2,3,1,3,0,0,0,2,1,2,2,3,0,3,3,3, 0,1,3,2,3,3,3,1,1,1,1,2,0,1,2,1,3,2,3,1,1,3,2,2,2,3,1,3,2,3,0,0, }, { 0, 1, 2, 4, 7, -1 }, { 2, 7 } }, { // subkey bits 12-17 { 3,0,3,1,1,0,2,2,3,1,2,0,3,3,2,3,0,1,0,1,2,3,0,2,0,2,0,1,0,0,1,0, 2,3,1,2,1,0,2,0,2,1,0,1,0,2,1,0,3,1,2,3,1,3,1,1,1,2,0,2,2,0,0,0, }, { 0, 1, 2, 3, 6, 7 }, { 0, 1 } }, { // subkey bits 18-23 { 3,2,0,3,0,2,2,1,1,2,3,2,1,3,2,1,2,2,1,3,3,2,1,0,1,0,1,3,0,0,0,2, 2,1,0,1,0,1,0,1,3,1,1,2,2,3,2,0,3,3,2,0,2,1,3,3,0,0,3,0,1,1,3,3, }, { 0, 1, 3, 5, 6, 7 }, { 4, 5 } }, }; static const struct sbox fn1_r2_boxes[4] = { { // subkey bits 24-29 { 3,3,2,0,3,0,3,1,0,3,0,1,0,2,1,3,1,3,0,3,3,1,3,3,3,2,3,2,2,3,1,2, 0,2,2,1,0,1,2,0,3,3,0,1,3,2,1,2,3,0,1,3,0,1,2,2,1,2,1,2,0,1,3,0, }, { 0, 1, 2, 3, 6, -1 }, { 1, 6 } }, { // subkey bits 30-35 { 1,2,3,2,1,3,0,1,1,0,2,0,0,2,3,2,3,3,0,1,2,2,1,0,1,0,1,2,3,2,1,3, 2,2,2,0,1,0,2,3,2,1,2,1,2,1,0,3,0,1,2,3,1,2,1,3,2,0,3,2,3,0,2,0, }, { 2, 4, 5, 6, 7, -1 }, { 5, 7 } }, { // subkey bits 36-41 { 0,1,0,2,1,1,0,1,0,2,2,2,1,3,0,0,1,1,3,1,2,2,2,3,1,0,3,3,3,2,2,2, 1,1,3,0,3,1,3,0,1,3,3,2,1,1,0,0,1,2,2,2,1,1,1,2,2,0,0,3,2,3,1,3, }, { 1, 2, 3, 4, 5, 7 }, { 0, 3 } }, { // subkey bits 42-47 { 2,1,0,3,3,3,2,0,1,2,1,1,1,0,3,1,1,3,3,0,1,2,1,0,0,0,3,0,3,0,3,0, 1,3,3,3,0,3,2,0,2,1,2,2,2,1,1,3,0,1,0,1,0,1,1,1,1,3,1,0,1,2,3,3, }, { 0, 1, 3, 4, 6, 7 }, { 2, 4 } }, }; static const struct sbox fn1_r3_boxes[4] = { { // subkey bits 48-53 { 0,0,0,3,3,1,1,0,2,0,2,0,0,0,3,2,0,1,2,3,2,2,1,0,3,0,0,0,0,0,2,3, 3,0,0,1,1,2,3,3,0,1,3,2,0,1,3,3,2,0,0,1,0,2,0,0,0,3,1,3,3,3,3,3, }, { 0, 1, 5, 6, 7, -1 }, { 0, 5 } }, { // subkey bits 54-59 { 2,3,2,3,0,2,3,0,2,2,3,0,3,2,0,2,1,0,2,3,1,1,1,0,0,1,0,2,1,2,2,1, 3,0,2,1,2,3,3,0,3,2,3,1,0,2,1,0,1,2,2,3,0,2,1,3,1,3,0,2,1,1,1,3, }, { 2, 3, 4, 6, 7, -1 }, { 6, 7 } }, { // subkey bits 60-65 { 3,0,2,1,1,3,1,2,2,1,2,2,2,0,0,1,2,3,1,0,2,0,0,2,3,1,2,0,0,0,3,0, 2,1,1,2,0,0,1,2,3,1,1,2,0,1,3,0,3,1,1,0,0,2,3,0,0,0,0,3,2,0,0,0, }, { 0, 2, 3, 4, 5, 6 }, { 1, 4 } }, { // subkey bits 66-71 { 0,1,0,0,2,1,3,2,3,3,2,1,0,1,1,1,1,1,0,3,3,1,1,0,0,2,2,1,0,3,3,2, 1,3,3,0,3,0,2,1,1,2,3,2,2,2,1,0,0,3,3,3,2,2,3,1,0,2,3,0,3,1,1,0, }, { 0, 1, 2, 3, 5, 7 }, { 2, 3 } }, }; static const struct sbox fn1_r4_boxes[4] = { { // subkey bits 72-77 { 1,1,1,1,1,0,1,3,3,2,3,0,1,2,0,2,3,3,0,1,2,1,2,3,0,3,2,3,2,0,1,2, 0,1,0,3,2,1,3,2,3,1,2,3,2,0,1,2,2,0,0,0,2,1,3,0,3,1,3,0,1,3,3,0, }, { 1, 2, 3, 4, 5, 7 }, { 0, 4 } }, { // subkey bits 78-83 { 3,0,0,0,0,1,0,2,3,3,1,3,0,3,1,2,2,2,3,1,0,0,2,0,1,0,2,2,3,3,0,0, 1,1,3,0,2,3,0,3,0,3,0,2,0,2,0,1,0,3,0,1,3,1,1,0,0,1,3,3,2,2,1,0, }, { 0, 1, 2, 3, 5, 6 }, { 1, 3 } }, { // subkey bits 84-89 { 0,1,1,2,0,1,3,1,2,0,3,2,0,0,3,0,3,0,1,2,2,3,3,2,3,2,0,1,0,0,1,0, 3,0,2,3,0,2,2,2,1,1,0,2,2,0,0,1,2,1,1,1,2,3,0,3,1,2,3,3,1,1,3,0, }, { 0, 2, 4, 5, 6, 7 }, { 2, 6 } }, { // subkey bits 90-95 { 0,1,2,2,0,1,0,3,2,2,1,1,3,2,0,2,0,1,3,3,0,2,2,3,3,2,0,0,2,1,3,3, 1,1,1,3,1,2,1,1,0,3,3,2,3,2,3,0,3,1,0,0,3,0,0,0,2,2,2,1,2,3,0,0, }, { 0, 1, 3, 4, 6, 7 }, { 5, 7 } }, }; /******************************************************************************/ static const struct sbox fn2_r1_boxes[4] = { { // subkey bits 0- 5 { 2,0,2,0,3,0,0,3,1,1,0,1,3,2,0,1,2,0,1,2,0,2,0,2,2,2,3,0,2,1,3,0, 0,1,0,1,2,2,3,3,0,3,0,2,3,0,1,2,1,1,0,2,0,3,1,1,2,2,1,3,1,1,3,1, }, { 0, 3, 4, 5, 7, -1 }, { 6, 7 } }, { // subkey bits 6-11 { 1,1,0,3,0,2,0,1,3,0,2,0,1,1,0,0,1,3,2,2,0,2,2,2,2,0,1,3,3,3,1,1, 1,3,1,3,2,2,2,2,2,2,0,1,0,1,1,2,3,1,1,2,0,3,3,3,2,2,3,1,1,1,3,0, }, { 1, 2, 3, 4, 6, -1 }, { 3, 5 } }, { // subkey bits 12-17 { 1,0,2,2,3,3,3,3,1,2,2,1,0,1,2,1,1,2,3,1,2,0,0,1,2,3,1,2,0,0,0,2, 2,0,1,1,0,0,2,0,0,0,2,3,2,3,0,1,3,0,0,0,2,3,2,0,1,3,2,1,3,1,1,3, }, { 1, 2, 4, 5, 6, 7 }, { 1, 4 } }, { // subkey bits 18-23 { 1,3,3,0,3,2,3,1,3,2,1,1,3,3,2,1,2,3,0,3,1,0,0,2,3,0,0,0,3,3,0,1, 2,3,0,0,0,1,2,1,3,0,0,1,0,2,2,2,3,3,1,2,1,3,0,0,0,3,0,1,3,2,2,0, }, { 0, 2, 3, 5, 6, 7 }, { 0, 2 } }, }; static const struct sbox fn2_r2_boxes[4] = { { // subkey bits 24-29 { 3,1,3,0,3,0,3,1,3,0,0,1,1,3,0,3,1,1,0,1,2,3,2,3,3,1,2,2,2,0,2,3, 2,2,2,1,1,3,3,0,3,1,2,1,1,1,0,2,0,3,3,0,0,2,0,0,1,1,2,1,2,1,1,0, }, { 0, 2, 4, 6, -1, -1 }, { 4, 6 } }, { // subkey bits 30-35 { 0,3,0,3,3,2,1,2,3,1,1,1,2,0,2,3,0,3,1,2,2,1,3,3,3,2,1,2,2,0,1,0, 2,3,0,1,2,0,1,1,2,0,2,1,2,0,2,3,3,1,0,2,3,3,0,3,1,1,3,0,0,1,2,0, }, { 1, 3, 4, 5, 6, 7 }, { 0, 3 } }, { // subkey bits 36-41 { 0,0,2,1,3,2,1,0,1,2,2,2,1,1,0,3,1,2,2,3,2,1,1,0,3,0,0,1,1,2,3,1, 3,3,2,2,1,0,1,1,1,2,0,1,2,3,0,3,3,0,3,2,2,0,2,2,1,2,3,2,1,0,2,1, }, { 0, 1, 3, 4, 5, 7 }, { 1, 7 } }, { // subkey bits 42-47 { 0,2,1,2,0,2,2,0,1,3,2,0,3,2,3,0,3,3,2,3,1,2,3,1,2,2,0,0,2,2,1,2, 2,3,3,3,1,1,0,0,0,3,2,0,3,2,3,1,1,1,1,0,1,0,1,3,0,0,1,2,2,3,2,0, }, { 1, 2, 3, 5, 6, 7 }, { 2, 5 } }, }; static const struct sbox fn2_r3_boxes[4] = { { // subkey bits 48-53 { 2,1,2,1,2,3,1,3,2,2,1,3,3,0,0,1,0,2,0,3,3,1,0,0,1,1,0,2,3,2,1,2, 1,1,2,1,1,3,2,2,0,2,2,3,3,3,2,0,0,0,0,0,3,3,3,0,1,2,1,0,2,3,3,1, }, { 2, 3, 4, 6, -1, -1 }, { 3, 5 } }, { // subkey bits 54-59 { 3,2,3,3,1,0,3,0,2,0,1,1,1,0,3,0,3,1,3,1,0,1,2,3,2,2,3,2,0,1,1,2, 3,0,0,2,1,0,0,2,2,0,1,0,0,2,0,0,1,3,1,3,2,0,3,3,1,0,2,2,2,3,0,0, }, { 0, 1, 3, 5, 7, -1 }, { 0, 2 } }, { // subkey bits 60-65 { 2,2,1,0,2,3,3,0,0,0,1,3,1,2,3,2,2,3,1,3,0,3,0,3,3,2,2,1,0,0,0,2, 1,2,2,2,0,0,1,2,0,1,3,0,2,3,2,1,3,2,2,2,3,1,3,0,2,0,2,1,0,3,3,1, }, { 0, 1, 2, 3, 5, 7 }, { 1, 6 } }, { // subkey bits 66-71 { 1,2,3,2,0,2,1,3,3,1,0,1,1,2,2,0,0,1,1,1,2,1,1,2,0,1,3,3,1,1,1,2, 3,3,1,0,2,1,1,1,2,1,0,0,2,2,3,2,3,2,2,0,2,2,3,3,0,2,3,0,2,2,1,1, }, { 0, 2, 4, 5, 6, 7 }, { 4, 7 } }, }; static const struct sbox fn2_r4_boxes[4] = { { // subkey bits 72-77 { 2,0,1,1,2,1,3,3,1,1,1,2,0,1,0,2,0,1,2,0,2,3,0,2,3,3,2,2,3,2,0,1, 3,0,2,0,2,3,1,3,2,0,0,1,1,2,3,1,1,1,0,1,2,0,3,3,1,1,1,3,3,1,1,0, }, { 0, 1, 3, 6, 7, -1 }, { 0, 3 } }, { // subkey bits 78-83 { 1,2,2,1,0,3,3,1,0,2,2,2,1,0,1,0,1,1,0,1,0,2,1,0,2,1,0,2,3,2,3,3, 2,2,1,2,2,3,1,3,3,3,0,1,0,1,3,0,0,0,1,2,0,3,3,2,3,2,1,3,2,1,0,2, }, { 0, 1, 2, 4, 5, 6 }, { 4, 7 } }, { // subkey bits 84-89 { 2,3,2,1,3,2,3,0,0,2,1,1,0,0,3,2,3,1,0,1,2,2,2,1,3,2,2,1,0,2,1,2, 0,3,1,0,0,3,1,1,3,3,2,0,1,0,1,3,0,0,1,2,1,2,3,2,1,0,0,3,2,1,1,3, }, { 0, 2, 3, 4, 5, 7 }, { 1, 2 } }, { // subkey bits 90-95 { 2,0,0,3,2,2,2,1,3,3,1,1,2,0,0,3,1,0,3,2,1,0,2,0,3,2,2,3,2,0,3,0, 1,3,0,2,2,1,3,3,0,1,0,3,1,1,3,2,0,3,0,2,3,2,1,3,2,3,0,0,1,3,2,1, }, { 2, 3, 4, 5, 6, 7 }, { 5, 6 } }, }; /******************************************************************************/ static uint8_t fn(uint8_t in, const struct optimised_sbox *sboxes, uint32_t key) { const struct optimised_sbox *sbox1 = &sboxes[0]; const struct optimised_sbox *sbox2 = &sboxes[1]; const struct optimised_sbox *sbox3 = &sboxes[2]; const struct optimised_sbox *sbox4 = &sboxes[3]; return sbox1->output[sbox1->input_lookup[in] ^ ((key >> 0) & 0x3f)] | sbox2->output[sbox2->input_lookup[in] ^ ((key >> 6) & 0x3f)] | sbox3->output[sbox3->input_lookup[in] ^ ((key >> 12) & 0x3f)] | sbox4->output[sbox4->input_lookup[in] ^ ((key >> 18) & 0x3f)]; } // srckey is the 64-bit master key (2x32 bits) // dstkey will contain the 96-bit key for the 1st FN (4x24 bits) static void expand_1st_key(uint32_t *dstkey, const uint32_t *srckey) { static const int bits[96] = { 33, 58, 49, 36, 0, 31, 22, 30, 3, 16, 5, 53, 10, 41, 23, 19, 27, 39, 43, 6, 34, 12, 61, 21, 48, 13, 32, 35, 6, 42, 43, 14, 21, 41, 52, 25, 18, 47, 46, 37, 57, 53, 20, 8, 55, 54, 59, 60, 27, 33, 35, 18, 8, 15, 63, 1, 50, 44, 16, 46, 5, 4, 45, 51, 38, 25, 13, 11, 62, 29, 48, 2, 59, 61, 62, 56, 51, 57, 54, 9, 24, 63, 22, 7, 26, 42, 45, 40, 23, 14, 2, 31, 52, 28, 44, 17, }; int i; dstkey[0] = 0; dstkey[1] = 0; dstkey[2] = 0; dstkey[3] = 0; for (i = 0; i < 96; ++i) dstkey[i / 24] |= BIT(srckey[bits[i] / 32], bits[i] % 32) << (i % 24); } // srckey is the 64-bit master key (2x32 bits) XORed with the subkey // dstkey will contain the 96-bit key for the 2nd FN (4x24 bits) static void expand_2nd_key(uint32_t *dstkey, const uint32_t *srckey) { static const int bits[96] = { 34, 9, 32, 24, 44, 54, 38, 61, 47, 13, 28, 7, 29, 58, 18, 1, 20, 60, 15, 6, 11, 43, 39, 19, 63, 23, 16, 62, 54, 40, 31, 3, 56, 61, 17, 25, 47, 38, 55, 57, 5, 4, 15, 42, 22, 7, 2, 19, 46, 37, 29, 39, 12, 30, 49, 57, 31, 41, 26, 27, 24, 36, 11, 63, 33, 16, 56, 62, 48, 60, 59, 32, 12, 30, 53, 48, 10, 0, 50, 35, 3, 59, 14, 49, 51, 45, 44, 2, 21, 33, 55, 52, 23, 28, 8, 26, }; int i; dstkey[0] = 0; dstkey[1] = 0; dstkey[2] = 0; dstkey[3] = 0; for (i = 0; i < 96; ++i) dstkey[i / 24] |= BIT(srckey[bits[i] / 32], bits[i] % 32) << (i % 24); } // seed is the 16-bit seed generated by the first FN // subkey will contain the 64-bit key to be XORed with the master key // for the 2nd FN (2x32 bits) static void expand_subkey(uint32_t* subkey, uint16_t seed) { // Note that each row of the table is a permutation of the seed bits. static const int bits[64] = { 5, 10, 14, 9, 4, 0, 15, 6, 1, 8, 3, 2, 12, 7, 13, 11, 5, 12, 7, 2, 13, 11, 9, 14, 4, 1, 6, 10, 8, 0, 15, 3, 4, 10, 2, 0, 6, 9, 12, 1, 11, 7, 15, 8, 13, 5, 14, 3, 14, 11, 12, 7, 4, 5, 2, 10, 1, 15, 0, 9, 8, 6, 13, 3, }; int i; subkey[0] = 0; subkey[1] = 0; for (i = 0; i < 64; ++i) subkey[i / 32] |= BIT(seed, bits[i]) << (i % 32); } static uint16_t feistel(uint16_t val, const int *bitsA, const int *bitsB, const struct optimised_sbox* boxes1, const struct optimised_sbox* boxes2, const struct optimised_sbox* boxes3, const struct optimised_sbox* boxes4, uint32_t key1, uint32_t key2, uint32_t key3, uint32_t key4) { uint8_t l = bitswap<8>(val, bitsB[7],bitsB[6],bitsB[5],bitsB[4],bitsB[3],bitsB[2],bitsB[1],bitsB[0]); uint8_t r = bitswap<8>(val, bitsA[7],bitsA[6],bitsA[5],bitsA[4],bitsA[3],bitsA[2],bitsA[1],bitsA[0]); l ^= fn(r, boxes1, key1); r ^= fn(l, boxes2, key2); l ^= fn(r, boxes3, key3); r ^= fn(l, boxes4, key4); return (BIT(l, 0) << bitsA[0]) | (BIT(l, 1) << bitsA[1]) | (BIT(l, 2) << bitsA[2]) | (BIT(l, 3) << bitsA[3]) | (BIT(l, 4) << bitsA[4]) | (BIT(l, 5) << bitsA[5]) | (BIT(l, 6) << bitsA[6]) | (BIT(l, 7) << bitsA[7]) | (BIT(r, 0) << bitsB[0]) | (BIT(r, 1) << bitsB[1]) | (BIT(r, 2) << bitsB[2]) | (BIT(r, 3) << bitsB[3]) | (BIT(r, 4) << bitsB[4]) | (BIT(r, 5) << bitsB[5]) | (BIT(r, 6) << bitsB[6]) | (BIT(r, 7) << bitsB[7]); } static int extract_inputs(uint32_t val, const int *inputs) { int i; int res = 0; for (i = 0; i < 6; ++i) { if (inputs[i] != -1) res |= BIT(val, inputs[i]) << i; } return res; } static void optimise_sboxes(struct optimised_sbox* out, const struct sbox* in) { int box; for (box = 0; box < 4; ++box) { int i; // precalculate the input lookup for (i = 0; i < 256; ++i) { out[box].input_lookup[i] = extract_inputs(i, in[box].inputs); } // precalculate the output masks for (i = 0; i < 64; ++i) { int o = in[box].table[i]; out[box].output[i] = 0; if (o & 1) out[box].output[i] |= 1 << in[box].outputs[0]; if (o & 2) out[box].output[i] |= 1 << in[box].outputs[1]; } } } static void cps2_decrypt(running_machine &machine, uint16_t *rom, uint16_t *dec, int length, const uint32_t *master_key, uint32_t lower_limit, uint32_t upper_limit) { int i; uint32_t key1[4]; struct optimised_sbox sboxes1[4*4]; struct optimised_sbox sboxes2[4*4]; optimise_sboxes(&sboxes1[0*4], fn1_r1_boxes); optimise_sboxes(&sboxes1[1*4], fn1_r2_boxes); optimise_sboxes(&sboxes1[2*4], fn1_r3_boxes); optimise_sboxes(&sboxes1[3*4], fn1_r4_boxes); optimise_sboxes(&sboxes2[0*4], fn2_r1_boxes); optimise_sboxes(&sboxes2[1*4], fn2_r2_boxes); optimise_sboxes(&sboxes2[2*4], fn2_r3_boxes); optimise_sboxes(&sboxes2[3*4], fn2_r4_boxes); // expand master key to 1st FN 96-bit key expand_1st_key(key1, master_key); // add extra bits for s-boxes with less than 6 inputs key1[0] ^= BIT(key1[0], 1) << 4; key1[0] ^= BIT(key1[0], 2) << 5; key1[0] ^= BIT(key1[0], 8) << 11; key1[1] ^= BIT(key1[1], 0) << 5; key1[1] ^= BIT(key1[1], 8) << 11; key1[2] ^= BIT(key1[2], 1) << 5; key1[2] ^= BIT(key1[2], 8) << 11; for (i = 0; i < 0x10000; ++i) { int a; uint16_t seed; uint32_t subkey[2]; uint32_t key2[4]; if ((i & 0xff) == 0) { char loadingMessage[256]; // for displaying with UI sprintf(loadingMessage, "Decrypting %d%%", i*100/0x10000); machine.ui().set_startup_text(loadingMessage,false); } // pass the address through FN1 seed = feistel(i, fn1_groupA, fn1_groupB, &sboxes1[0*4], &sboxes1[1*4], &sboxes1[2*4], &sboxes1[3*4], key1[0], key1[1], key1[2], key1[3]); // expand the result to 64-bit expand_subkey(subkey, seed); // XOR with the master key subkey[0] ^= master_key[0]; subkey[1] ^= master_key[1]; // expand key to 2nd FN 96-bit key expand_2nd_key(key2, subkey); // add extra bits for s-boxes with less than 6 inputs key2[0] ^= BIT(key2[0], 0) << 5; key2[0] ^= BIT(key2[0], 6) << 11; key2[1] ^= BIT(key2[1], 0) << 5; key2[1] ^= BIT(key2[1], 1) << 4; key2[2] ^= BIT(key2[2], 2) << 5; key2[2] ^= BIT(key2[2], 3) << 4; key2[2] ^= BIT(key2[2], 7) << 11; key2[3] ^= BIT(key2[3], 1) << 5; // decrypt the opcodes for (a = i; a < length/2; a += 0x10000) { if (a >= lower_limit && a <= upper_limit) { dec[a] = feistel(rom[a], fn2_groupA, fn2_groupB, &sboxes2[0 * 4], &sboxes2[1 * 4], &sboxes2[2 * 4], &sboxes2[3 * 4], key2[0], key2[1], key2[2], key2[3]); } else { dec[a] = rom[a]; } } } } struct game_keys { const char *name; /* game driver name */ const uint32_t keys[2]; uint32_t upper_limit; }; void cps2_state::init_cps2crypt() { if (m_region_key) { unsigned short decoded[10] = { 0 }; for (int b = 0; b < 10 * 16; b++) { int bit = (317 - b) % 160; if ((m_region_key->base()[bit / 8] >> ((bit ^ 7) % 8)) & 1) { decoded[b / 16] |= (0x8000 >> (b % 16)); } } uint32_t key[2] = { ((uint32_t)decoded[0] << 16) | decoded[1], ((uint32_t)decoded[2] << 16) | decoded[3] }; // decoded[4] == watchdog instruction third word // decoded[5] == watchdog instruction second word // decoded[6] == watchdog instruction first word // decoded[7] == 0x4000 (bits 8 to 23 of CPS2 object output address) // decoded[8] == 0x0900 uint32_t lower, upper; if (decoded[9] == 0xffff) { // On a dead board, the only encrypted range is actually FF0000-FFFFFF. // It doesn't start from 0, and it's the upper half of a 128kB bank. upper = 0xffffff; lower = 0xff0000; } else { upper = (((~decoded[9] & 0x3ff) << 14) | 0x3fff) + 1; lower = 0; } logerror("cps2 decrypt 0x%08x,0x%08x,0x%08x,0x%08x\n", key[0], key[1], lower, upper); // we have a proper key so use it to decrypt cps2_decrypt(machine(), (uint16_t *)memregion("maincpu")->base(), m_decrypted_opcodes, memregion("maincpu")->bytes(), key, lower / 2, upper / 2); } }