LXR linux/include/crypto/chacha.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Common values and helper functions for the ChaCha and XChaCha stream ciphers.
   4 *
   5 * XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's
   6 * security.  Here they share the same key size, tfm context, and setkey
   7 * function; only their IV size and encrypt/decrypt function differ.
   8 *
   9 * The ChaCha paper specifies 20, 12, and 8-round variants.  In general, it is
  10 * recommended to use the 20-round variant ChaCha20.  However, the other
  11 * variants can be needed in some performance-sensitive scenarios.  The generic
  12 * ChaCha code currently allows only the 20 and 12-round variants.
  13 */
  14
  15#ifndef _CRYPTO_CHACHA_H
  16#define _CRYPTO_CHACHA_H
  17
  18#include <crypto/skcipher.h>
  19#include <linux/types.h>
  20#include <linux/crypto.h>
  21
  22/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
  23#define CHACHA_IV_SIZE          16
  24
  25#define CHACHA_KEY_SIZE         32
  26#define CHACHA_BLOCK_SIZE       64
  27#define CHACHAPOLY_IV_SIZE      12
  28
  29/* 192-bit nonce, then 64-bit stream position */
  30#define XCHACHA_IV_SIZE         32
  31
  32struct chacha_ctx {
  33        u32 key[8];
  34        int nrounds;
  35};
  36
  37void chacha_block(u32 *state, u8 *stream, int nrounds);
  38static inline void chacha20_block(u32 *state, u8 *stream)
  39{
  40        chacha_block(state, stream, 20);
  41}
  42void hchacha_block(const u32 *in, u32 *out, int nrounds);
  43
  44void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv);
  45
  46int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
  47                           unsigned int keysize);
  48int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key,
  49                           unsigned int keysize);
  50
  51int crypto_chacha_crypt(struct skcipher_request *req);
  52int crypto_xchacha_crypt(struct skcipher_request *req);
  53
  54#endif /* _CRYPTO_CHACHA_H */
  55