1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434
//! Holochain HCID base32 encoding utility. //! //! # Example //! //! ``` //! extern crate hcid; //! //! fn main() { //! let enc = hcid::HcidEncoding::with_kind("hcs0").unwrap(); //! let key = enc.encode(&[0; 32]).unwrap(); //! assert_eq!("HcSciaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", key); //! let buffer = enc.decode(&key).unwrap(); //! assert_eq!([0; 32].to_vec(), buffer); //! } //! ``` extern crate reed_solomon; mod error; mod b32; pub use error::{HcidError, HcidResult}; mod util; use util::{b32_correct, cap_decode, cap_encode_bin, char_upper}; static HC_CODE_MAP: &'static [[u8; 2]] = &[ [ 0xb2, 0xff ], // 51: hc30, reserved [ 0xb4, 0xff ], // 52: hc40, reserved [ 0xb6, 0xff ], // 53: hc50, reserved [ 0xb8, 0xff ], // 54: hc60, reserved [ 0xba, 0xff ], // 55: hc70, reserved [ 0xbc, 0xff ], // 56: hc80, reserved [ 0xbe, 0xff ], // 57: hc90, reserved // 58-61: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 62-65: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 66-69: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 70-73: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 74-77: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 78-81: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 82-85: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 86-89: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 90-93: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], // 94-96: reserved [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0xff, 0xff ], [ 0x80, 0xff ], // 97: hca0, reserved [ 0x82, 0xff ], // 98: hcb0, reserved [ 0x84, 0xff ], // 99: hcc0, reserved [ 0x86, 0xff ], // 100: hcd0, reserved [ 0x88, 0xff ], // 101: hce0, reserved [ 0x8a, 0xff ], // 102: hcf0, reserved [ 0x8c, 0xff ], // 103: hcg0, reserved [ 0x8e, 0xff ], // 104: hch0, reserved [ 0x90, 0xff ], // 105: hci0, reserved [ 0x92, 0xff ], // 106: hcj0, reserved [ 0x94, 0xff ], // 107: hck0, reserved [ 0xff, 0xff ], // 108: reserved, reserved [ 0x96, 0xff ], // 109: hcm0, reserved [ 0x98, 0xff ], // 110: hcn0, reserved [ 0x9a, 0xff ], // 111: hco0, reserved [ 0x9c, 0xff ], // 112: hcp0, reserved [ 0x9e, 0xff ], // 113: hcq0, reserved [ 0xa0, 0xff ], // 114: hcr0, reserved [ 0xa2, 0xff ], // 115: hcs0, reserved [ 0xa4, 0xff ], // 116: hct0, reserved [ 0xa6, 0xff ], // 117: hcu0, reserved [ 0xa8, 0xff ], // 118: hcv0, reserved [ 0xaa, 0xff ], // 119: hcw0, reserved [ 0xad, 0xff ], // 120: hcx0, reserved [ 0xae, 0xff ], // 121: hcy0, reserved [ 0xb0, 0xff ], // 122: hcz0, reserved ]; /* XXX * * HcK v0 hex: 0x389424 * HcK v1 hex: 0x389524 * HcA v0 hex: 0x388024 * HcA v1 hex: 0x388124 * HcS v0 hex: 0x38a224 * HcS v1 hex: 0x38a324 * * XXX */ /// represents an encoding configuration for hcid rendering and parsing pub struct HcidEncodingConfig { /// byte count of actuall key data that will be encoded pub key_byte_count: usize, /// parity bytes that will be encoded directly into the base32 string (appended after key) pub base_parity_byte_count: usize, /// parity bytes that will be encoded in the alpha capitalization (appended after base parity) pub cap_parity_byte_count: usize, /// bytes to prefix before rendering to base32 pub prefix: Vec<u8>, /// binary indication of the capitalization for prefix characters pub prefix_cap: Vec<u8>, /// how many characters are in a capitalization parity segment pub cap_segment_char_count: usize, /// how many characters long the fully rendered base32 string should be pub encoded_char_count: usize, } impl HcidEncodingConfig { /// create a new config given a kind token string /// /// # Example /// /// ``` /// extern crate hcid; /// let hca0 = hcid::HcidEncodingConfig::new("hca0").unwrap(); /// let hck0 = hcid::HcidEncodingConfig::new("hck0").unwrap(); /// let hcs0 = hcid::HcidEncodingConfig::new("hcs0").unwrap(); /// ``` pub fn new(kind: &str) -> HcidResult<Self> { let kind_b = kind.as_bytes(); if kind_b.len() != 4 || kind_b[0] != 104 || kind_b[1] != 99 || (kind_b[3] != 48 && kind_b[3] != 49) || kind_b[2] < 51 || kind_b[2] > 122 { return Err(format!("invalid kind: `{}`", kind).into()); } let version = if kind_b[3] == 48 { 0 } else { 1 }; let res = HC_CODE_MAP[(kind_b[2] - 51) as usize][version as usize]; if res == 0xff { return Err(format!("invalid kind: `{}`", kind).into()); } Ok(HcidEncodingConfig { key_byte_count: 32, base_parity_byte_count: 4, cap_parity_byte_count: 4, prefix: vec![0x38, res, 0x24], prefix_cap: b"101".to_vec(), cap_segment_char_count: 15, encoded_char_count: 63, }) } } /// an instance that can encode / decode a particular hcid encoding configuration pub struct HcidEncoding { config: HcidEncodingConfig, rs_enc: reed_solomon::Encoder, rs_dec: reed_solomon::Decoder, } impl HcidEncoding { /// create a new HcidEncoding instance from given HcidEncodingConfig pub fn new(config: HcidEncodingConfig) -> HcidResult<Self> { // set up a reed-solomon encoder with proper parity count let rs_enc = reed_solomon::Encoder::new( config.base_parity_byte_count + config.cap_parity_byte_count, ); // set up a reed-solomon decoder with proper parity count let rs_dec = reed_solomon::Decoder::new( config.base_parity_byte_count + config.cap_parity_byte_count, ); Ok(Self { config, rs_enc, rs_dec, }) } /// create a new config given a kind token string /// /// # Example /// /// ``` /// extern crate hcid; /// let hca0 = hcid::HcidEncoding::with_kind("hca0").unwrap(); /// let hck0 = hcid::HcidEncoding::with_kind("hck0").unwrap(); /// let hcs0 = hcid::HcidEncoding::with_kind("hcs0").unwrap(); /// ``` pub fn with_kind(kind: &str) -> HcidResult<Self> { HcidEncoding::new(HcidEncodingConfig::new(kind)?) } /// encode a string to base32 with this instance's configuration pub fn encode(&self, data: &[u8]) -> HcidResult<String> { if data.len() != self.config.key_byte_count { return Err(HcidError(String::from(format!( "BadDataLen:{},Expected:{}", data.len(), self.config.key_byte_count )))); } // generate reed-solomon parity bytes let full_parity = self.rs_enc.encode(data); // extract the bytes that will be encoded as capitalization let cap_bytes = &full_parity[full_parity.len() - self.config.cap_parity_byte_count..]; // base is the bytes that will be base32 encoded let mut base = self.config.prefix.clone(); base.extend_from_slice( &full_parity[0..full_parity.len() - self.config.cap_parity_byte_count], ); // do the base32 encoding let mut base32 = b32::encode(&base); if base32.len() != self.config.encoded_char_count { return Err(HcidError(String::from(format!( "InternalGeneratedBadLen:{},Expected:{}", base32.len(), self.config.encoded_char_count )))); } // capitalize the prefix with a fixed scheme cap_encode_bin( &mut base32[0..self.config.prefix_cap.len()], &self.config.prefix_cap, 3, )?; // iterate over segments, applying parity capitalization for i in 0..cap_bytes.len() { let seg_start = self.config.prefix_cap.len() + (i * self.config.cap_segment_char_count); let seg = &mut base32[seg_start..seg_start + self.config.cap_segment_char_count]; let bin = format!("{:08b}", cap_bytes[i]).into_bytes(); cap_encode_bin(seg, &bin, 8)?; } // we only use ascii characters // use unchecked for performance / so we don't allocate again unsafe { // return the result as a String for ease of use Ok(String::from_utf8_unchecked(base32)) } } /// decode the data from a base32 string with this instance's configuration. Reed-Solomon can /// correct up to 1/2 its parity size worth of erasures (if no other errors are present). pub fn decode(&self, data: &str) -> HcidResult<Vec<u8>> { // get our parsed data with erasures let (data, erasures) = self.pre_decode(data)?; if erasures.len() > ( self.config.base_parity_byte_count + self.config.cap_parity_byte_count ) / 2 { // our reed-solomon library makes bad corrections once erasure count exceeds 1/2 the // parity count (it takes 2 parity symbols to find/correct one error, 1 parity symbol to // correct a known erasure) return Err(HcidError(String::from("TooManyErrors"))); } // optimise for the case where there are no transcription errors // this makes correcting more expensive if there *are*, // but on average makes the system more efficient if self.pre_is_corrupt(&data, &erasures)? { // apply reed-solomon correction // will "throw" on too many errors Ok( self.rs_dec.correct(&data, Some(&erasures[..]))?[0..self.config.key_byte_count] .to_vec(), ) } else { Ok(data[0..self.config.key_byte_count].to_vec()) } } /// a lighter-weight check to determine if a base32 string is corrupt pub fn is_corrupt(&self, data: &str) -> HcidResult<bool> { // get our parsed data with erasures let (data, erasures) = match self.pre_decode(data) { Ok(v) => v, Err(_) => return Ok(true), }; match self.pre_is_corrupt(&data, &erasures) { Ok(v) => Ok(v), Err(_) => Ok(true), } } /// internal helper for is_corrupt checking fn pre_is_corrupt(&self, data: &[u8], erasures: &[u8]) -> HcidResult<bool> { // if we have any erasures, we can exit early if erasures.len() > 0 { return Ok(true); } // slightly more efficient reed-solomon corruption check Ok(self.rs_dec.is_corrupted(&data)) } /// internal helper for preparing decoding fn pre_decode(&self, data: &str) -> HcidResult<(Vec<u8>, Vec<u8>)> { if data.len() != self.config.encoded_char_count { return Err(HcidError(String::from(format!( "BadIdLen:{},Expected:{}", data.len(), self.config.encoded_char_count )))); } let key_base_byte_size = self.config.key_byte_count + self.config.base_parity_byte_count; // All char_erasures are indexed from the 0th char of the full codeword w/ prefix, but // byte_erasures are indexed from the 0th byte of the key+parity (ie. without the prefix). // Any byte of key, or base/cap parity could be erased. let mut byte_erasures = vec![b'0'; key_base_byte_size + self.config.cap_parity_byte_count]; let mut char_erasures = vec![b'0'; data.len()]; // correct any transliteration errors into our base32 alphabet // marking any unrecognizable characters as char-level erasures let mut data = b32_correct(data.as_bytes(), &mut char_erasures); // Pull out the parity data that was encoded as capitalization. If its erasure, // determine the let mut cap_bytes: Vec<u8> = Vec::new(); let mut all_zro = true; let mut all_one = true; for i in 0..self.config.cap_parity_byte_count { // For cap. parity, indexing starts after pre-defined Base-32 prefix let char_idx = self.config.prefix_cap.len() + (i * self.config.cap_segment_char_count); match cap_decode( char_idx, &data[char_idx..char_idx + self.config.cap_segment_char_count], &char_erasures )? { None => { byte_erasures[key_base_byte_size + i] = b'1'; cap_bytes.push(0) } Some(parity) => { if all_zro && parity != 0x00_u8 { all_zro = false } if all_one && parity != 0xFF_u8 { all_one = false } cap_bytes.push(parity) } } } // If either all caps or all lower case (or erasure), assume the casing was lost (eg. QR // code, or dns segment); mark all cap-derived parity as erasures. This allows validation // of codeword if all remaining parity is intact and key is correct; since no parity // capacity remains, no correction will be attempted. There is only a low probability that // any remaining errors will be detected, in this case. However, we're no *worse* off than // if we had no R-S parity at all. if all_zro || all_one { for i in 0..self.config.cap_parity_byte_count { byte_erasures[key_base_byte_size + i] = b'1'; } } // we have the cap data, uppercase everything for c in data.iter_mut() { char_upper(c); } // do the base32 decode let mut data = b32::decode(&data)?; if &data[0..self.config.prefix.len()] != self.config.prefix.as_slice() { return Err(HcidError(String::from("PrefixMismatch"))); } // remove the prefix bytes data.drain(0..self.config.prefix.len()); // append our cap parity bytes data.append(&mut cap_bytes); // Sort through the char-level erasures (5 bits), and associate them with byte-level data (8 // bits) -- in the (now prefix-free) data buffer, so that we mark the proper erasures for // reed-solomon correction. Some of these chars span multiple bytes... we need to mark both. for i in self.config.prefix_cap.len()..char_erasures.len() { let c = char_erasures[i]; if c == b'1' { // 1st and last bit of 5-bit segment may index different bytes byte_erasures[( i * 5 + 0 ) / 8 - self.config.prefix.len()] = b'1'; byte_erasures[( i * 5 + 4 ) / 8 - self.config.prefix.len()] = b'1'; } } // translate erasures into the form expected by our reed-solomon lib let mut erasures: Vec<u8> = Vec::new(); for i in 0..byte_erasures.len() { if byte_erasures[i] == b'1' { data[i] = 0; erasures.push(i as u8); } } Ok((data, erasures)) } } #[cfg(test)] mod tests { use super::*; static TEST_HEX_1: &'static str = "0c71db50d35d760b0ea2002ff20147c7c3a8e8030d35ef28ed1adaec9e329aba"; static TEST_ID_1: &'static str = "HcKciDds5OiogymxbnHKEabQ8iavqs8dwdVaGdJW76Vp4gx47tQDfGW4OWc9w5i"; #[test] fn it_encodes_1() { let enc = HcidEncoding::with_kind("hck0").unwrap(); let input = hex::decode(TEST_HEX_1.as_bytes()).unwrap(); let id = enc.encode(&input).unwrap(); assert_eq!(TEST_ID_1, id); } #[test] fn it_decodes_1() { let enc = HcidEncoding::with_kind("hck0").unwrap(); let data = hex::encode(&enc.decode(TEST_ID_1).unwrap()); assert_eq!(TEST_HEX_1, data); } }