implement save file decryption/encryption

src/SaveFileFormats.cc

@@ -0,0 +1,89 @@
+#include "SaveFileFormats.hh"
+
+#include <string>
+#include <stdexcept>
+
+using namespace std;
+
+
+
+ShuffleTables::ShuffleTables(PSOV2Encryption& crypt) {
+  for (size_t x = 0; x < 0x100; x++) {
+    this->forward_table[x] = x;
+  }
+
+  int32_t r28 = 0xFF;
+  uint8_t* r31 = &this->forward_table[0xFF];
+  while (r28 >= 0) {
+    uint32_t r3 = this->pseudorand(crypt, r28 + 1);
+    if (r3 >= 0x100) {
+      throw logic_error("bad r3");
+    }
+    uint8_t t = this->forward_table[r3];
+    this->forward_table[r3] = *r31;
+    *r31 = t;
+
+    this->reverse_table[t] = r28;
+    r31--;
+    r28--;
+  }
+}
+
+uint32_t ShuffleTables::pseudorand(PSOV2Encryption& crypt, uint32_t prev) {
+  return (((prev & 0xFFFF) * ((crypt.next() >> 16) & 0xFFFF)) >> 16) & 0xFFFF;
+}
+
+void ShuffleTables::shuffle(void* vdest, const void* vsrc, size_t size, bool reverse) const {
+  uint8_t* dest = reinterpret_cast<uint8_t*>(vdest);
+  const uint8_t* src = reinterpret_cast<const uint8_t*>(vsrc);
+  const uint8_t* table = reverse ? this->reverse_table : this->forward_table;
+
+  for (size_t block_offset = 0; block_offset < (size & 0xFFFFFF00); block_offset += 0x100) {
+    for (size_t z = 0; z < 0x100; z++) {
+      dest[block_offset + table[z]] = src[block_offset + z];
+    }
+  }
+
+  // Any remaining bytes that don't fill an entire block are not shuffled
+  memcpy(&dest[size & 0xFFFFFF00], &src[size & 0xFFFFFF00], size & 0xFF);
+}
+
+
+
+bool PSOGCIFileHeader::checksum_correct() const {
+  uint32_t cs = crc32(&this->game_name, this->game_name.bytes());
+  cs = crc32(&this->embedded_seed, sizeof(this->embedded_seed), cs);
+  cs = crc32(&this->file_name, this->file_name.bytes(), cs);
+  cs = crc32(&this->banner, this->banner.bytes(), cs);
+  cs = crc32(&this->icon, this->icon.bytes(), cs);
+  cs = crc32(&this->data_size, sizeof(this->data_size), cs);
+  cs = crc32("\0\0\0\0", 4, cs); // this->checksum (treated as zero)
+  return (cs == this->checksum);
+}
+
+void PSOGCIFileHeader::check() const {
+  if (!this->checksum_correct()) {
+    throw runtime_error("GCI file unencrypted header checksum is incorrect");
+  }
+  if (this->developer_id[0] != '8' || this->developer_id[1] != 'P') {
+    throw runtime_error("GCI file is not for a Sega game");
+  }
+  if (this->game_id[0] != 'G') {
+    throw runtime_error("GCI file is not for a GameCube game");
+  }
+  if (this->game_id[1] != 'P') {
+    throw runtime_error("GCI file is not for Phantasy Star Online");
+  }
+  if ((this->game_id[1] != 'P') ||
+      ((this->game_id[2] != 'S') && (this->game_id[2] != 'O'))) {
+    throw runtime_error("GCI file is not for Phantasy Star Online");
+  }
+}
+
+bool PSOGCIFileHeader::is_ep12() const {
+  return (this->game_id[2] == 'O');
+}
+
+bool PSOGCIFileHeader::is_ep3() const {
+  return (this->game_id[2] == 'S');
+}