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| 1 | +use std::env; |
| 2 | +use bitstream_io::{BigEndian, BitReader, BitRead, BitWriter, BitWrite}; |
| 3 | + |
| 4 | +const JUMON_MOJI_TABLE: [char; 64] = [ |
| 5 | + 'あ', 'い', 'う', 'え', 'お', 'か', 'き', 'く', |
| 6 | + 'け', 'こ', 'さ', 'し', 'す', 'せ', 'そ', 'た', |
| 7 | + 'ち', 'つ', 'て', 'と', 'な', 'に', 'ぬ', 'ね', |
| 8 | + 'の', 'は', 'ひ', 'ふ', 'へ', 'ほ', 'ま', 'み', |
| 9 | + 'む', 'め', 'も', 'や', 'ゆ', 'よ', 'ら', 'り', |
| 10 | + 'る', 'れ', 'ろ', 'わ', 'が', 'ぎ', 'ぐ', 'げ', |
| 11 | + 'ご', 'ざ', 'じ', 'ず', 'ぜ', 'ぞ', 'だ', 'ぢ', |
| 12 | + 'づ', 'で', 'ど', 'ば', 'び', 'ぶ', 'べ', 'ぼ', |
| 13 | +]; |
| 14 | + |
| 15 | +const NAME_MOJI_TABLE: [char; 64] = [ |
| 16 | + '０', '１', '２', '３', '４', '５', '６', '７', |
| 17 | + '８', '９', 'あ', 'い', 'う', 'え', 'お', 'か', |
| 18 | + 'き', 'く', 'け', 'こ', 'さ', 'し', 'す', 'せ', |
| 19 | + 'そ', 'た', 'ち', 'つ', 'て', 'と', 'な', 'に', |
| 20 | + 'ぬ', 'ね', 'の', 'は', 'ひ', 'ふ', 'へ', 'ほ', |
| 21 | + 'ま', 'み', 'む', 'め', 'も', 'や', 'ゆ', 'よ', |
| 22 | + 'ら', 'り', 'る', 'れ', 'ろ', 'わ', 'を', 'ん', |
| 23 | + 'っ', 'ゃ', 'ゅ', 'ょ', '゛', '゜', 'ー', ' ', |
| 24 | +]; |
| 25 | + |
| 26 | +#[derive(Clone, Copy, Debug, Default)] |
| 27 | +struct GameData { |
| 28 | + // Player name: 4 characters (from `NAME_MOJI_TABLE`, 6 bits each) |
| 29 | + name: [char; 4], |
| 30 | + // Experience: 16 bits |
| 31 | + experience: u16, |
| 32 | + // Gold: 16 bits |
| 33 | + gold: u16, |
| 34 | + // Weapon ID: 3 bits |
| 35 | + weapon: u8, |
| 36 | + // Armor ID: 3 bits |
| 37 | + armor: u8, |
| 38 | + // Shield ID: 2 bits |
| 39 | + shield: u8, |
| 40 | + // やくそう count: 4 bits |
| 41 | + herbs: u8, |
| 42 | + // まほうのカギ count: 4 bits |
| 43 | + keys: u8, |
| 44 | + // Item IDs: 8 slots, 4 bits each |
| 45 | + items: [u8; 8], |
| 46 | + // Progress flags, 5 total, 1 bit each |
| 47 | + progress_flags: [bool; 5], |
| 48 | + // Encryption key, 3 bits |
| 49 | + encryption_key: u8, |
| 50 | + // Checksum, 8 bits |
| 51 | + checksum: u8, |
| 52 | +} |
| 53 | + |
| 54 | +impl GameData { |
| 55 | + fn from_bytes(bytes: &[u8]) -> Self { |
| 56 | + let mut data = Self::default(); |
| 57 | + |
| 58 | + let mut reader = BitReader::endian(bytes, BigEndian); |
| 59 | + |
| 60 | + data.items[1] = reader.read::<u8>(4).unwrap(); |
| 61 | + data.items[0] = reader.read::<u8>(4).unwrap(); |
| 62 | + |
| 63 | + data.progress_flags[0] = reader.read::<u8>(1).unwrap() != 0; |
| 64 | + data.name[1] = NAME_MOJI_TABLE[reader.read::<u8>(6).unwrap() as usize]; |
| 65 | + data.progress_flags[1] = reader.read::<u8>(1).unwrap() != 0; |
| 66 | + |
| 67 | + data.experience |= reader.read::<u16>(8).unwrap() << 8; |
| 68 | + |
| 69 | + data.items[5] = reader.read::<u8>(4).unwrap(); |
| 70 | + data.items[4] = reader.read::<u8>(4).unwrap(); |
| 71 | + |
| 72 | + data.herbs = reader.read::<u8>(4).unwrap(); |
| 73 | + data.keys = reader.read::<u8>(4).unwrap(); |
| 74 | + |
| 75 | + data.gold |= reader.read::<u16>(8).unwrap() << 8; |
| 76 | + |
| 77 | + data.weapon = reader.read::<u8>(3).unwrap(); |
| 78 | + data.armor = reader.read::<u8>(3).unwrap(); |
| 79 | + data.shield = reader.read::<u8>(2).unwrap(); |
| 80 | + |
| 81 | + data.encryption_key |= reader.read::<u8>(1).unwrap() << 2; |
| 82 | + data.progress_flags[2] = reader.read::<u8>(1).unwrap() != 0; |
| 83 | + data.name[3] = NAME_MOJI_TABLE[reader.read::<u8>(6).unwrap() as usize]; |
| 84 | + |
| 85 | + data.items[7] = reader.read::<u8>(4).unwrap(); |
| 86 | + data.items[6] = reader.read::<u8>(4).unwrap(); |
| 87 | + |
| 88 | + data.name[0] = NAME_MOJI_TABLE[reader.read::<u8>(6).unwrap() as usize]; |
| 89 | + data.progress_flags[3] = reader.read::<u8>(1).unwrap() != 0; |
| 90 | + data.encryption_key |= reader.read::<u8>(1).unwrap() << 1; |
| 91 | + |
| 92 | + data.gold |= reader.read::<u16>(8).unwrap(); |
| 93 | + |
| 94 | + data.items[3] = reader.read::<u8>(4).unwrap(); |
| 95 | + data.items[2] = reader.read::<u8>(4).unwrap(); |
| 96 | + |
| 97 | + data.encryption_key |= reader.read::<u8>(1).unwrap(); |
| 98 | + data.progress_flags[4] = reader.read::<u8>(1).unwrap() != 0; |
| 99 | + data.name[2] = NAME_MOJI_TABLE[reader.read::<u8>(6).unwrap() as usize]; |
| 100 | + |
| 101 | + data.experience |= reader.read::<u16>(8).unwrap(); |
| 102 | + |
| 103 | + data.checksum = reader.read::<u8>(8).unwrap(); |
| 104 | + |
| 105 | + return data; |
| 106 | + } |
| 107 | +} |
| 108 | + |
| 109 | +fn decode(input: &str) -> Result<Vec<u8>, String> { |
| 110 | + // Decode characters |
| 111 | + let mut decrypted_characters: [u8; 20] = [ 0; 20 ]; |
| 112 | + let mut last_character_code = 0; |
| 113 | + for (index, character) in input.chars().enumerate() { |
| 114 | + let character_code = JUMON_MOJI_TABLE.iter().position(|&moji| moji == character); |
| 115 | + if character_code.is_none() { |
| 116 | + return Err(format!("Unsupported input character: {}", character)); |
| 117 | + } |
| 118 | + |
| 119 | + let character_code_u8 = u8::try_from(character_code.unwrap()).unwrap(); |
| 120 | + let decrypted = character_code_u8.wrapping_sub(last_character_code).wrapping_sub(4) & 0b00111111; |
| 121 | + last_character_code = character_code_u8; |
| 122 | + |
| 123 | + decrypted_characters[index] = decrypted; |
| 124 | + } |
| 125 | + |
| 126 | + // Pack characters into bytes |
| 127 | + let mut writer = BitWriter::endian(Vec::new(), BigEndian); |
| 128 | + for character in decrypted_characters.iter().rev() { |
| 129 | + writer.write(6, *character).unwrap(); |
| 130 | + } |
| 131 | + let mut input_bytes = writer.into_writer(); |
| 132 | + |
| 133 | + // Calculate the correct checksum (XMODEM-CRC) |
| 134 | + let mut crc = 0_u8; |
| 135 | + let mut divisor = 0x8000_u16; |
| 136 | + for byte in input_bytes[..input_bytes.len() - 1].iter() { |
| 137 | + for bit in 0..8 { |
| 138 | + if divisor & 0x8000 != 0 { |
| 139 | + divisor = (divisor << 1) ^ 0x1021; |
| 140 | + } else { |
| 141 | + divisor <<= 1; |
| 142 | + } |
| 143 | + |
| 144 | + if *byte & (1 << bit) != 0 { |
| 145 | + crc ^= divisor as u8; |
| 146 | + } |
| 147 | + } |
| 148 | + } |
| 149 | + |
| 150 | + // Confirm that the CRC is correct |
| 151 | + let last_byte = input_bytes.last_mut().unwrap(); |
| 152 | + if crc == *last_byte { |
| 153 | + return Ok(input_bytes); |
| 154 | + } else { |
| 155 | + return Err("Invalid CRC".to_string()); |
| 156 | + } |
| 157 | +} |
| 158 | + |
| 159 | +fn process(input: &str) -> Result<String, String> { |
| 160 | + if input.chars().count() != 20 { |
| 161 | + return Err("Input must be 20 characters.".to_string()); |
| 162 | + } |
| 163 | + |
| 164 | + let result = decode(input); |
| 165 | + if result.is_ok() { |
| 166 | + return Ok("The password is already valid.".to_string()); |
| 167 | + } |
| 168 | + |
| 169 | + let mut substitutions: Vec<(String, GameData)> = Vec::new(); |
| 170 | + for input_index_to_replace in 0..input.len() { |
| 171 | + for moji_index in 0..JUMON_MOJI_TABLE.len() { |
| 172 | + let mut new_string = String::with_capacity(input.len()); |
| 173 | + for (input_index, input_character) in input.chars().enumerate() { |
| 174 | + if input_index == input_index_to_replace { |
| 175 | + new_string.push(JUMON_MOJI_TABLE[moji_index]); |
| 176 | + } else { |
| 177 | + new_string.push(input_character); |
| 178 | + } |
| 179 | + } |
| 180 | + if let Ok(decoded) = decode(&new_string) { |
| 181 | + let data = GameData::from_bytes(decoded.as_slice()); |
| 182 | + substitutions.push((String::from(new_string), data)); |
| 183 | + } |
| 184 | + } |
| 185 | + } |
| 186 | + |
| 187 | + if substitutions.len() > 0 { |
| 188 | + let mut output = String::new(); |
| 189 | + output += &format!("Found {} substitutions:\n", substitutions.len()); |
| 190 | + for (password, data) in substitutions { |
| 191 | + output += &format!("{}\n{:?}\n\n", password, data); |
| 192 | + } |
| 193 | + return Ok(output.trim_end().to_string()); |
| 194 | + } |
| 195 | + |
| 196 | + return Err("Recovery failed".to_string()); |
| 197 | +} |
| 198 | + |
| 199 | +fn main() { |
| 200 | + let args: Vec<String> = env::args().collect(); |
| 201 | + let program = args[0].clone(); |
| 202 | + |
| 203 | + if args.len() < 2 { |
| 204 | + eprintln!("usage: {} <input>", program); |
| 205 | + return; |
| 206 | + } |
| 207 | + |
| 208 | + let result = process(&args[1]); |
| 209 | + match result { |
| 210 | + Ok(output) => println!("{}", output), |
| 211 | + Err(err) => eprintln!("{}", err), |
| 212 | + } |
| 213 | +} |
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