| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * ChaCha stream cipher |
| 4 | * |
| 5 | * (c) 2015 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 12 | * Catacomb is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU Library General Public License as |
| 14 | * published by the Free Software Foundation; either version 2 of the |
| 15 | * License, or (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with Catacomb; if not, write to the Free |
| 24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | #ifndef CATACOMB_CHACHA_H |
| 29 | #define CATACOMB_CHACHA_H |
| 30 | |
| 31 | #ifdef __cplusplus |
| 32 | extern "C" { |
| 33 | #endif |
| 34 | |
| 35 | /*----- Header files ------------------------------------------------------*/ |
| 36 | |
| 37 | #include <mLib/bits.h> |
| 38 | |
| 39 | #ifndef CATACOMB_GCIPHER_H |
| 40 | # include "gcipher.h" |
| 41 | #endif |
| 42 | |
| 43 | #ifndef CATACOMB_GRAND_H |
| 44 | # include "grand.h" |
| 45 | #endif |
| 46 | |
| 47 | /*----- Constants ---------------------------------------------------------*/ |
| 48 | |
| 49 | #define CHACHA_NONCESZ 8u |
| 50 | #define CHACHA_KEYSZ 32u |
| 51 | #define CHACHA_OUTSZ 64u |
| 52 | |
| 53 | #define HCHACHA_INSZ 16u |
| 54 | #define HCHACHA_OUTSZ 32u |
| 55 | |
| 56 | #define XCHACHA_NONCESZ 24u |
| 57 | #define XCHACHA_KEYSZ CHACHA_KEYSZ |
| 58 | #define XCHACHA_OUTSZ CHACHA_OUTSZ |
| 59 | |
| 60 | /*----- Data structures ---------------------------------------------------*/ |
| 61 | |
| 62 | typedef uint32 chacha_matrix[16]; |
| 63 | |
| 64 | typedef struct chacha_ctx { |
| 65 | chacha_matrix a; |
| 66 | octet buf[CHACHA_OUTSZ]; |
| 67 | size_t bufi; |
| 68 | } chacha_ctx; |
| 69 | |
| 70 | #define XCHACHA_DEFCTX(name) \ |
| 71 | typedef struct name { chacha_ctx s; chacha_matrix k; } name |
| 72 | XCHACHA_DEFCTX(xchacha20_ctx); |
| 73 | XCHACHA_DEFCTX(xchacha12_ctx); |
| 74 | XCHACHA_DEFCTX(xchacha8_ctx); |
| 75 | |
| 76 | /*----- The ChaCha stream cipher ------------------------------------------*/ |
| 77 | |
| 78 | /* --- @chacha_init@ --- * |
| 79 | * |
| 80 | * Arguments: @chacha_ctx *ctx@ = context to fill in |
| 81 | * @const void *key@ = pointer to key material |
| 82 | * @size_t ksz@ = size of key (either 32 or 16) |
| 83 | * @const void *nonce@ = initial nonce, or null |
| 84 | * |
| 85 | * Returns: --- |
| 86 | * |
| 87 | * Use: Initializes a ChaCha context ready for use. |
| 88 | */ |
| 89 | |
| 90 | extern void chacha_init(chacha_ctx */*ctx*/, |
| 91 | const void */*key*/, size_t /*ksz*/, |
| 92 | const void */*nonce*/); |
| 93 | |
| 94 | /* --- @chacha_setnonce@ --- * |
| 95 | * |
| 96 | * Arguments: @chacha_ctx *ctx@ = pointer to context |
| 97 | * @const void *nonce@ = the nonce (@CHACHA_NONCESZ@ bytes) |
| 98 | * |
| 99 | * Returns: --- |
| 100 | * |
| 101 | * Use: Set a new nonce in the context @ctx@, e.g., for processing a |
| 102 | * different message. The stream position is reset to zero (see |
| 103 | * @chacha_seek@ etc.). |
| 104 | */ |
| 105 | |
| 106 | extern void chacha_setnonce(chacha_ctx */*ctx*/, const void */*nonce*/); |
| 107 | |
| 108 | /* --- @chacha_seek@, @chacha_seeku64@ --- * |
| 109 | * |
| 110 | * Arguments: @chacha_ctx *ctx@ = pointer to context |
| 111 | * @unsigned long i@, @kludge64 i@ = new position to set |
| 112 | * |
| 113 | * Returns: --- |
| 114 | * |
| 115 | * Use: Sets a new stream position, in units of ChaCha output |
| 116 | * blocks, which are @CHACHA_OUTSZ@ bytes each. Byte |
| 117 | * granularity can be achieved by calling @chacha_encrypt@ |
| 118 | * appropriately. |
| 119 | */ |
| 120 | |
| 121 | extern void chacha_seek(chacha_ctx */*ctx*/, unsigned long /*i*/); |
| 122 | extern void chacha_seeku64(chacha_ctx */*ctx*/, kludge64 /*i*/); |
| 123 | |
| 124 | /* --- @chacha_tell@, @chacha_tellu64@ --- * |
| 125 | * |
| 126 | * Arguments: @chacha_ctx *ctx@ = pointer to context |
| 127 | * |
| 128 | * Returns: The current position in the output stream, in blocks, |
| 129 | * rounding upwards. |
| 130 | */ |
| 131 | |
| 132 | extern unsigned long chacha_tell(chacha_ctx */*ctx*/); |
| 133 | extern kludge64 chacha_tellu64(chacha_ctx */*ctx*/); |
| 134 | |
| 135 | /* --- @chacha{20,12,8}_encrypt@ --- * |
| 136 | * |
| 137 | * Arguments: @chacha_ctx *ctx@ = pointer to context |
| 138 | * @const void *src@ = source buffer (or null) |
| 139 | * @void *dest@ = destination buffer (or null) |
| 140 | * @size_t sz@ = size of the buffers |
| 141 | * |
| 142 | * Returns: --- |
| 143 | * |
| 144 | * Use: Encrypts or decrypts @sz@ bytes of data from @src@ to @dest@. |
| 145 | * ChaCha works by XORing plaintext with a keystream, so |
| 146 | * encryption and decryption are the same operation. If @dest@ |
| 147 | * is null then ignore @src@ and skip @sz@ bytes of the |
| 148 | * keystream. If @src@ is null, then just write the keystream |
| 149 | * to @dest@. |
| 150 | */ |
| 151 | |
| 152 | extern void chacha20_encrypt(chacha_ctx */*ctx*/, |
| 153 | const void */*src*/, void */*dest*/, |
| 154 | size_t /*sz*/); |
| 155 | extern void chacha12_encrypt(chacha_ctx */*ctx*/, |
| 156 | const void */*src*/, void */*dest*/, |
| 157 | size_t /*sz*/); |
| 158 | extern void chacha8_encrypt(chacha_ctx */*ctx*/, |
| 159 | const void */*src*/, void */*dest*/, |
| 160 | size_t /*sz*/); |
| 161 | |
| 162 | /*----- The HChaCha pseudorandom function ---------------------------------*/ |
| 163 | |
| 164 | /* --- @hchacha{20,12,8}_prf@ --- * |
| 165 | * |
| 166 | * Arguments: @chacha_ctx *ctx@ = pointer to context |
| 167 | * @const void *src@ = the input (@HCHACHA_INSZ@ bytes) |
| 168 | * @void *dest@ = the output (@HCHACHA_OUTSZ@ bytes) |
| 169 | * |
| 170 | * Returns: --- |
| 171 | * |
| 172 | * Use: Apply the HChaCha/r pseudorandom function to @src@, writing |
| 173 | * the result to @out@. |
| 174 | */ |
| 175 | |
| 176 | extern void hchacha20_prf(chacha_ctx */*ctx*/, |
| 177 | const void */*src*/, void */*dest*/); |
| 178 | extern void hchacha12_prf(chacha_ctx */*ctx*/, |
| 179 | const void */*src*/, void */*dest*/); |
| 180 | extern void hchacha8_prf(chacha_ctx */*ctx*/, |
| 181 | const void */*src*/, void */*dest*/); |
| 182 | |
| 183 | /*----- The XChaCha stream cipher ----------------------------------------*/ |
| 184 | |
| 185 | /* --- @xchacha{20,12,8}_init@ --- * |
| 186 | * |
| 187 | * Arguments: @xchachaR_ctx *ctx@ = the context to fill in |
| 188 | * @const void *key@ = pointer to key material |
| 189 | * @size_t ksz@ = size of key (either 32 or 16) |
| 190 | * @const void *nonce@ = initial nonce, or null |
| 191 | * |
| 192 | * Returns: --- |
| 193 | * |
| 194 | * Use: Initializes an XChaCha/r context ready for use. |
| 195 | * |
| 196 | * There is a different function for each number of rounds, |
| 197 | * unlike for plain ChaCha. |
| 198 | */ |
| 199 | |
| 200 | extern void xchacha20_init(xchacha20_ctx */*ctx*/, |
| 201 | const void */*key*/, size_t /*ksz*/, |
| 202 | const void */*nonce*/); |
| 203 | extern void xchacha12_init(xchacha12_ctx */*ctx*/, |
| 204 | const void */*key*/, size_t /*ksz*/, |
| 205 | const void */*nonce*/); |
| 206 | extern void xchacha8_init(xchacha8_ctx */*ctx*/, |
| 207 | const void */*key*/, size_t /*ksz*/, |
| 208 | const void */*nonce*/); |
| 209 | |
| 210 | /* --- @xchacha{20,12,8}_setnonce@ --- * |
| 211 | * |
| 212 | * Arguments: @xchachaR_ctx *ctx@ = pointer to context |
| 213 | * @const void *nonce@ = the nonce (@XCHACHA_NONCESZ@ bytes) |
| 214 | * |
| 215 | * Returns: --- |
| 216 | * |
| 217 | * Use: Set a new nonce in the context @ctx@, e.g., for processing a |
| 218 | * different message. The stream position is reset to zero (see |
| 219 | * @chacha_seek@ etc.). |
| 220 | * |
| 221 | * There is a different function for each number of rounds, |
| 222 | * unlike for plain ChaCha. |
| 223 | */ |
| 224 | |
| 225 | extern void xchacha20_setnonce(xchacha20_ctx */*ctx*/, |
| 226 | const void */*nonce*/); |
| 227 | extern void xchacha12_setnonce(xchacha12_ctx */*ctx*/, |
| 228 | const void */*nonce*/); |
| 229 | extern void xchacha8_setnonce(xchacha8_ctx */*ctx*/, |
| 230 | const void */*nonce*/); |
| 231 | |
| 232 | /* --- @xchacha{20,12,8}_seek@, @xchacha{20,12,8}_seeku64@ --- * |
| 233 | * |
| 234 | * Arguments: @xchachaR_ctx *ctx@ = pointer to context |
| 235 | * @unsigned long i@, @kludge64 i@ = new position to set |
| 236 | * |
| 237 | * Returns: --- |
| 238 | * |
| 239 | * Use: Sets a new stream position, in units of ChaCha output |
| 240 | * blocks, which are @XCHACHA_OUTSZ@ bytes each. Byte |
| 241 | * granularity can be achieved by calling @xchachaR_encrypt@ |
| 242 | * appropriately. |
| 243 | * |
| 244 | * There is a different function for each number of rounds, |
| 245 | * unlike for plain ChaCha, because the context structures are |
| 246 | * different. |
| 247 | */ |
| 248 | |
| 249 | extern void xchacha20_seek(xchacha20_ctx */*ctx*/, unsigned long /*i*/); |
| 250 | extern void xchacha12_seek(xchacha12_ctx */*ctx*/, unsigned long /*i*/); |
| 251 | extern void xchacha8_seek(xchacha8_ctx */*ctx*/, unsigned long /*i*/); |
| 252 | extern void xchacha20_seeku64(xchacha20_ctx */*ctx*/, kludge64 /*i*/); |
| 253 | extern void xchacha12_seeku64(xchacha12_ctx */*ctx*/, kludge64 /*i*/); |
| 254 | extern void xchacha8_seeku64(xchacha8_ctx */*ctx*/, kludge64 /*i*/); |
| 255 | |
| 256 | /* --- @xchacha{20,12,8}_tell@, @xchacha{20,12,8}_tellu64@ --- * |
| 257 | * |
| 258 | * Arguments: @chacha_ctx *ctx@ = pointer to context |
| 259 | * |
| 260 | * Returns: The current position in the output stream, in blocks, |
| 261 | * rounding upwards. |
| 262 | * |
| 263 | * There is a different function for each number of rounds, |
| 264 | * unlike for plain ChaCha, because the context structures are |
| 265 | * different. |
| 266 | */ |
| 267 | |
| 268 | extern unsigned long xchacha20_tell(xchacha20_ctx */*ctx*/); |
| 269 | extern unsigned long xchacha12_tell(xchacha12_ctx */*ctx*/); |
| 270 | extern unsigned long xchacha8_tell(xchacha8_ctx */*ctx*/); |
| 271 | extern kludge64 xchacha20_tellu64(xchacha20_ctx */*ctx*/); |
| 272 | extern kludge64 xchacha12_tellu64(xchacha12_ctx */*ctx*/); |
| 273 | extern kludge64 xchacha8_tellu64(xchacha8_ctx */*ctx*/); |
| 274 | |
| 275 | /* --- @xchacha{20,12,8}_encrypt@ --- * |
| 276 | * |
| 277 | * Arguments: @xchachaR_ctx *ctx@ = pointer to context |
| 278 | * @const void *src@ = source buffer (or null) |
| 279 | * @void *dest@ = destination buffer (or null) |
| 280 | * @size_t sz@ = size of the buffers |
| 281 | * |
| 282 | * Returns: --- |
| 283 | * |
| 284 | * Use: Encrypts or decrypts @sz@ bytes of data from @src@ to @dest@. |
| 285 | * XChaCha works by XORing plaintext with a keystream, so |
| 286 | * encryption and decryption are the same operation. If @dest@ |
| 287 | * is null then ignore @src@ and skip @sz@ bytes of the |
| 288 | * keystream. If @src@ is null, then just write the keystream |
| 289 | * to @dest@. |
| 290 | */ |
| 291 | |
| 292 | extern void xchacha20_encrypt(xchacha20_ctx */*ctx*/, |
| 293 | const void */*src*/, void */*dest*/, |
| 294 | size_t /*sz*/); |
| 295 | extern void xchacha12_encrypt(xchacha12_ctx */*ctx*/, |
| 296 | const void */*src*/, void */*dest*/, |
| 297 | size_t /*sz*/); |
| 298 | extern void xchacha8_encrypt(xchacha8_ctx */*ctx*/, |
| 299 | const void */*src*/, void */*dest*/, |
| 300 | size_t /*sz*/); |
| 301 | |
| 302 | /*----- Generic cipher interface ------------------------------------------*/ |
| 303 | |
| 304 | extern const octet chacha_keysz[]; |
| 305 | #define chacha20_keysz chacha_keysz |
| 306 | #define chacha12_keysz chacha_keysz |
| 307 | #define chacha8_keysz chacha_keysz |
| 308 | #define xchacha_keysz chacha_keysz |
| 309 | #define xchacha20_keysz chacha_keysz |
| 310 | #define xchacha12_keysz chacha_keysz |
| 311 | #define xchacha8_keysz chacha_keysz |
| 312 | |
| 313 | const gccipher chacha20, chacha12, chacha8; |
| 314 | const gccipher xchacha20, xchacha12, xchacha8; |
| 315 | |
| 316 | /*----- Generic random number generator interface -------------------------*/ |
| 317 | |
| 318 | /* --- @chacha{,12,8}_rand@, @xchacha{,12,8}_rand@ --- * |
| 319 | * |
| 320 | * Arguments: @const void *k@ = pointer to key material |
| 321 | * @size_t ksz@ = size of key material |
| 322 | * @const void *n@ = pointer to nonce or null |
| 323 | * (@CHACHA_NONCESZ@ or @XCHACHA_NONCESZ@) |
| 324 | * |
| 325 | * Returns: Pointer to generic random number generator instance. |
| 326 | * |
| 327 | * Use: Creates a random number interface wrapper around |
| 328 | * the ChaCha or XChaCha stream ciphers. |
| 329 | */ |
| 330 | |
| 331 | extern grand *chacha20_rand(const void */*k*/, size_t /*ksz*/, |
| 332 | const void */*n*/); |
| 333 | extern grand *chacha12_rand(const void */*k*/, size_t /*ksz*/, |
| 334 | const void */*n*/); |
| 335 | extern grand *chacha8_rand(const void */*k*/, size_t /*ksz*/, |
| 336 | const void */*n*/); |
| 337 | extern grand *xchacha20_rand(const void */*k*/, size_t /*ksz*/, |
| 338 | const void */*n*/); |
| 339 | extern grand *xchacha12_rand(const void */*k*/, size_t /*ksz*/, |
| 340 | const void */*n*/); |
| 341 | extern grand *xchacha8_rand(const void */*k*/, size_t /*ksz*/, |
| 342 | const void */*n*/); |
| 343 | |
| 344 | enum { |
| 345 | CHACHA_SEEK = GRAND_SPECIFIC('S'), /* @unsigned long pos@ */ |
| 346 | CHACHA_SEEKU64, /* @kludge64 pos@ */ |
| 347 | CHACHA_TELL, /* @unsigned long *pos@ */ |
| 348 | CHACHA_TELLU64 /* @kludge64 *pos@ */ |
| 349 | }; |
| 350 | |
| 351 | /*----- That's all, folks -------------------------------------------------*/ |
| 352 | |
| 353 | #ifdef __cplusplus |
| 354 | } |
| 355 | #endif |
| 356 | |
| 357 | #endif |