mdw@git.distorted.org.uk Git - catacomb/blob - symm/chacha.h

   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_IETF_NONCESZ 12u
  51 #define CHACHA_KEYSZ 32u
  52 #define CHACHA_OUTSZ 64u
  53
  54 #define HCHACHA_INSZ 16u
  55 #define HCHACHA_OUTSZ 32u
  56
  57 #define XCHACHA_NONCESZ 24u
  58 #define XCHACHA_KEYSZ CHACHA_KEYSZ
  59 #define XCHACHA_OUTSZ CHACHA_OUTSZ
  60
  61 /*----- Data structures ---------------------------------------------------*/
  62
  63 typedef uint32 chacha_matrix[16];
  64
  65 typedef struct chacha_ctx {
  66   chacha_matrix a;
  67   octet b[CHACHA_OUTSZ];
  68   unsigned off;
  69 } chacha_ctx;
  70
  71 #define XCHACHA_DEFCTX(name)                                            \
  72   typedef struct name { chacha_ctx s; chacha_matrix k; } name
  73 XCHACHA_DEFCTX(xchacha20_ctx);
  74 XCHACHA_DEFCTX(xchacha12_ctx);
  75 XCHACHA_DEFCTX(xchacha8_ctx);
  76
  77 /*----- The ChaCha stream cipher ------------------------------------------*/
  78
  79 /* --- @chacha_init@ --- *
  80  *
  81  * Arguments:   @chacha_ctx *ctx@ = context to fill in
  82  *              @const void *key@ = pointer to key material
  83  *              @size_t ksz@ = size of key (either 32 or 16)
  84  *              @const void *nonce@ = initial nonce, or null
  85  *
  86  * Returns:     ---
  87  *
  88  * Use:         Initializes a ChaCha context ready for use.
  89  */
  90
  91 extern void chacha_init(chacha_ctx */*ctx*/,
  92                         const void */*key*/, size_t /*ksz*/,
  93                         const void */*nonce*/);
  94
  95 /* --- @chacha_setnonce{,_ietf}@ --- *
  96  *
  97  * Arguments:   @chacha_ctx *ctx@ = pointer to context
  98  *              @const void *nonce@ = the nonce (@CHACHA_NONCESZ@ or
  99  *                      @CHACHA_IETF_NONCESZ@ bytes)
 100  *
 101  * Returns:     ---
 102  *
 103  * Use:         Set a new nonce in the context @ctx@, e.g., for processing a
 104  *              different message.  The stream position is reset to zero (see
 105  *              @chacha_seek@ etc.).
 106  */
 107
 108 extern void chacha_setnonce(chacha_ctx */*ctx*/, const void */*nonce*/);
 109 extern void chacha_setnonce_ietf(chacha_ctx */*ctx*/, const void */*nonce*/);
 110
 111 /* --- @chacha_seek{,u64,_ietf}@ --- *
 112  *
 113  * Arguments:   @chacha_ctx *ctx@ = pointer to context
 114  *              @unsigned long i@, @kludge64 i@, @uint32 i@ = new position
 115  *
 116  * Returns:     ---
 117  *
 118  * Use:         Sets a new stream position, in units of Chacha output
 119  *              blocks, which are @CHACHA_OUTSZ@ bytes each.  Byte
 120  *              granularity can be achieved by calling @chachaR_encrypt@
 121  *              appropriately.
 122  */
 123
 124 extern void chacha_seek(chacha_ctx */*ctx*/, unsigned long /*i*/);
 125 extern void chacha_seeku64(chacha_ctx */*ctx*/, kludge64 /*i*/);
 126 extern void chacha_seek_ietf(chacha_ctx */*ctx*/, uint32 /*i*/);
 127
 128 /* --- @chacha_tell{,u64,_ietf}@ --- *
 129  *
 130  * Arguments:   @chacha_ctx *ctx@ = pointer to context
 131  *
 132  * Returns:     The current position in the output stream, in blocks,
 133  *              rounding upwards.
 134  */
 135
 136 extern unsigned long chacha_tell(chacha_ctx */*ctx*/);
 137 extern kludge64 chacha_tellu64(chacha_ctx */*ctx*/);
 138 extern uint32 chacha_tell_ietf(chacha_ctx */*ctx*/);
 139
 140 /* --- @chacha{20,12,8}_encrypt@ --- *
 141  *
 142  * Arguments:   @chacha_ctx *ctx@ = pointer to context
 143  *              @const void *src@ = source buffer (or null)
 144  *              @void *dest@ = destination buffer (or null)
 145  *              @size_t sz@ = size of the buffers
 146  *
 147  * Returns:     ---
 148  *
 149  * Use:         Encrypts or decrypts @sz@ bytes of data from @src@ to @dest@.
 150  *              ChaCha works by XORing plaintext with a keystream, so
 151  *              encryption and decryption are the same operation.  If @dest@
 152  *              is null then ignore @src@ and skip @sz@ bytes of the
 153  *              keystream.  If @src@ is null, then just write the keystream
 154  *              to @dest@.
 155  */
 156
 157 extern void chacha20_encrypt(chacha_ctx */*ctx*/,
 158                              const void */*src*/, void */*dest*/,
 159                              size_t /*sz*/);
 160 extern void chacha12_encrypt(chacha_ctx */*ctx*/,
 161                               const void */*src*/, void */*dest*/,
 162                               size_t /*sz*/);
 163 extern void chacha8_encrypt(chacha_ctx */*ctx*/,
 164                               const void */*src*/, void */*dest*/,
 165                               size_t /*sz*/);
 166
 167 /*----- The HChaCha pseudorandom function ---------------------------------*/
 168
 169 /* --- @hchacha{20,12,8}_prf@ --- *
 170  *
 171  * Arguments:   @chacha_ctx *ctx@ = pointer to context
 172  *              @const void *src@ = the input (@HCHACHA_INSZ@ bytes)
 173  *              @void *dest@ = the output (@HCHACHA_OUTSZ@ bytes)
 174  *
 175  * Returns:     ---
 176  *
 177  * Use:         Apply the HChaCha/r pseudorandom function to @src@, writing
 178  *              the result to @out@.
 179  */
 180
 181 extern void hchacha20_prf(chacha_ctx */*ctx*/,
 182                           const void */*src*/, void */*dest*/);
 183 extern void hchacha12_prf(chacha_ctx */*ctx*/,
 184                           const void */*src*/, void */*dest*/);
 185 extern void hchacha8_prf(chacha_ctx */*ctx*/,
 186                          const void */*src*/, void */*dest*/);
 187
 188 /*----- The XChaCha stream cipher ----------------------------------------*/
 189
 190 /* --- @xchacha{20,12,8}_init@ --- *
 191  *
 192  * Arguments:   @xchachaR_ctx *ctx@ = the context to fill in
 193  *              @const void *key@ = pointer to key material
 194  *              @size_t ksz@ = size of key (either 32 or 16)
 195  *              @const void *nonce@ = initial nonce, or null
 196  *
 197  * Returns:     ---
 198  *
 199  * Use:         Initializes an XChaCha/r context ready for use.
 200  *
 201  *              There is a different function for each number of rounds,
 202  *              unlike for plain ChaCha.
 203  */
 204
 205 extern void xchacha20_init(xchacha20_ctx */*ctx*/,
 206                            const void */*key*/, size_t /*ksz*/,
 207                            const void */*nonce*/);
 208 extern void xchacha12_init(xchacha12_ctx */*ctx*/,
 209                             const void */*key*/, size_t /*ksz*/,
 210                             const void */*nonce*/);
 211 extern void xchacha8_init(xchacha8_ctx */*ctx*/,
 212                            const void */*key*/, size_t /*ksz*/,
 213                            const void */*nonce*/);
 214
 215 /* --- @xchacha{20,12,8}_setnonce@ --- *
 216  *
 217  * Arguments:   @xchachaR_ctx *ctx@ = pointer to context
 218  *              @const void *nonce@ = the nonce (@XCHACHA_NONCESZ@ bytes)
 219  *
 220  * Returns:     ---
 221  *
 222  * Use:         Set a new nonce in the context @ctx@, e.g., for processing a
 223  *              different message.  The stream position is reset to zero (see
 224  *              @chacha_seek@ etc.).
 225  *
 226  *              There is a different function for each number of rounds,
 227  *              unlike for plain ChaCha.
 228  */
 229
 230 extern void xchacha20_setnonce(xchacha20_ctx */*ctx*/,
 231                                const void */*nonce*/);
 232 extern void xchacha12_setnonce(xchacha12_ctx */*ctx*/,
 233                                 const void */*nonce*/);
 234 extern void xchacha8_setnonce(xchacha8_ctx */*ctx*/,
 235                                const void */*nonce*/);
 236
 237 /* --- @xchacha{20,12,8}_seek{,u64}@ --- *
 238  *
 239  * Arguments:   @xchachaR_ctx *ctx@ = pointer to context
 240  *              @unsigned long i@, @kludge64 i@ = new position to set
 241  *
 242  * Returns:     ---
 243  *
 244  * Use:         Sets a new stream position, in units of ChaCha output
 245  *              blocks, which are @XCHACHA_OUTSZ@ bytes each.  Byte
 246  *              granularity can be achieved by calling @xchachaR_encrypt@
 247  *              appropriately.
 248  *
 249  *              There is a different function for each number of rounds,
 250  *              unlike for plain ChaCha, because the context structures are
 251  *              different.
 252  */
 253
 254 extern void xchacha20_seek(xchacha20_ctx */*ctx*/, unsigned long /*i*/);
 255 extern void xchacha12_seek(xchacha12_ctx */*ctx*/, unsigned long /*i*/);
 256 extern void xchacha8_seek(xchacha8_ctx */*ctx*/, unsigned long /*i*/);
 257 extern void xchacha20_seeku64(xchacha20_ctx */*ctx*/, kludge64 /*i*/);
 258 extern void xchacha12_seeku64(xchacha12_ctx */*ctx*/, kludge64 /*i*/);
 259 extern void xchacha8_seeku64(xchacha8_ctx */*ctx*/, kludge64 /*i*/);
 260
 261 /* --- @xchacha{20,12,8}_tell{,u64}@ --- *
 262  *
 263  * Arguments:   @chacha_ctx *ctx@ = pointer to context
 264  *
 265  * Returns:     The current position in the output stream, in blocks,
 266  *              rounding upwards.
 267  *
 268  *              There is a different function for each number of rounds,
 269  *              unlike for plain ChaCha, because the context structures are
 270  *              different.
 271  */
 272
 273 extern unsigned long xchacha20_tell(xchacha20_ctx */*ctx*/);
 274 extern unsigned long xchacha12_tell(xchacha12_ctx */*ctx*/);
 275 extern unsigned long xchacha8_tell(xchacha8_ctx */*ctx*/);
 276 extern kludge64 xchacha20_tellu64(xchacha20_ctx */*ctx*/);
 277 extern kludge64 xchacha12_tellu64(xchacha12_ctx */*ctx*/);
 278 extern kludge64 xchacha8_tellu64(xchacha8_ctx */*ctx*/);
 279
 280 /* --- @xchacha{20,12,8}_encrypt@ --- *
 281  *
 282  * Arguments:   @xchachaR_ctx *ctx@ = pointer to context
 283  *              @const void *src@ = source buffer (or null)
 284  *              @void *dest@ = destination buffer (or null)
 285  *              @size_t sz@ = size of the buffers
 286  *
 287  * Returns:     ---
 288  *
 289  * Use:         Encrypts or decrypts @sz@ bytes of data from @src@ to @dest@.
 290  *              XChaCha works by XORing plaintext with a keystream, so
 291  *              encryption and decryption are the same operation.  If @dest@
 292  *              is null then ignore @src@ and skip @sz@ bytes of the
 293  *              keystream.  If @src@ is null, then just write the keystream
 294  *              to @dest@.
 295  */
 296
 297 extern void xchacha20_encrypt(xchacha20_ctx */*ctx*/,
 298                             const void */*src*/, void */*dest*/,
 299                             size_t /*sz*/);
 300 extern void xchacha12_encrypt(xchacha12_ctx */*ctx*/,
 301                               const void */*src*/, void */*dest*/,
 302                               size_t /*sz*/);
 303 extern void xchacha8_encrypt(xchacha8_ctx */*ctx*/,
 304                               const void */*src*/, void */*dest*/,
 305                               size_t /*sz*/);
 306
 307 /*----- Generic cipher interface ------------------------------------------*/
 308
 309 extern const octet chacha_keysz[];
 310 #define chacha20_keysz chacha_keysz
 311 #define chacha12_keysz chacha_keysz
 312 #define chacha8_keysz chacha_keysz
 313 #define chacha_ietf_keysz chacha_keysz
 314 #define chacha20_ietf_keysz chacha_keysz
 315 #define chacha12_ietf_keysz chacha_keysz
 316 #define chacha8_ietf_keysz chacha_keysz
 317 #define xchacha_keysz chacha_keysz
 318 #define xchacha20_keysz chacha_keysz
 319 #define xchacha12_keysz chacha_keysz
 320 #define xchacha8_keysz chacha_keysz
 321
 322 extern const gccipher chacha20, chacha12, chacha8;
 323 extern const gccipher chacha20_ietf, chacha12_ietf, chacha8_ietf;
 324 extern const gccipher xchacha20, xchacha12, xchacha8;
 325
 326 /*----- Generic random number generator interface -------------------------*/
 327
 328 /* --- @chacha{20,12,8}{,_ietf}_rand@, @xchacha{20,12,8}_rand@ --- *
 329  *
 330  * Arguments:           @const void *k@ = pointer to key material
 331  *                      @size_t ksz@ = size of key material
 332  *                      @const void *n@ = pointer to nonce or null
 333  *                              (@CHACHA_NONCESZ@, @CHACHA_IETF_NONCESZ@, or
 334  *                              @XCHACHA_NONCESZ@)
 335  *
 336  * Returns:             Pointer to generic random number generator instance.
 337  *
 338  * Use:                 Creates a random number interface wrapper around
 339  *                      the ChaCha or XChaCha stream ciphers.
 340  */
 341
 342 extern grand *chacha20_rand(const void */*k*/, size_t /*ksz*/,
 343                             const void */*n*/);
 344 extern grand *chacha12_rand(const void */*k*/, size_t /*ksz*/,
 345                             const void */*n*/);
 346 extern grand *chacha8_rand(const void */*k*/, size_t /*ksz*/,
 347                            const void */*n*/);
 348 extern grand *chacha20_ietf_rand(const void */*k*/, size_t /*ksz*/,
 349                                  const void */*n*/);
 350 extern grand *chacha12_ietf_rand(const void */*k*/, size_t /*ksz*/,
 351                                  const void */*n*/);
 352 extern grand *chacha8_ietf_rand(const void */*k*/, size_t /*ksz*/,
 353                                 const void */*n*/);
 354 extern grand *xchacha20_rand(const void */*k*/, size_t /*ksz*/,
 355                              const void */*n*/);
 356 extern grand *xchacha12_rand(const void */*k*/, size_t /*ksz*/,
 357                              const void */*n*/);
 358 extern grand *xchacha8_rand(const void */*k*/, size_t /*ksz*/,
 359                             const void */*n*/);
 360
 361 enum {
 362   CHACHA_SEEK = GRAND_SPECIFIC('S'),    /* @unsigned long pos@ */
 363   CHACHA_SEEKU64,                       /* @kludge64 pos@ */
 364   CHACHA_TELL,                          /* @unsigned long *pos@ */
 365   CHACHA_TELLU64                        /* @kludge64 *pos@ */
 366 };
 367
 368 /*----- That's all, folks -------------------------------------------------*/
 369
 370 #ifdef __cplusplus
 371   }
 372 #endif
 373
 374 #endif