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 <asm/unaligned.h>
 19#include <linux/types.h>
 20
 21/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
 22#define CHACHA_IV_SIZE		16
 23
 24#define CHACHA_KEY_SIZE		32
 25#define CHACHA_BLOCK_SIZE	64
 26#define CHACHAPOLY_IV_SIZE	12
 27
 28#define CHACHA_STATE_WORDS	(CHACHA_BLOCK_SIZE / sizeof(u32))
 29
 30/* 192-bit nonce, then 64-bit stream position */
 31#define XCHACHA_IV_SIZE		32
 32
 33void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
 34static inline void chacha20_block(u32 *state, u8 *stream)
 35{
 36	chacha_block_generic(state, stream, 20);
 37}
 38
 39void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
 40void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
 41
 42static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
 43{
 44	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
 45		hchacha_block_arch(state, out, nrounds);
 46	else
 47		hchacha_block_generic(state, out, nrounds);
 48}
 49
 50static inline void chacha_init_consts(u32 *state)
 51{
 52	state[0]  = 0x61707865; /* "expa" */
 53	state[1]  = 0x3320646e; /* "nd 3" */
 54	state[2]  = 0x79622d32; /* "2-by" */
 55	state[3]  = 0x6b206574; /* "te k" */
 56}
 57
 58void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
 59static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
 60{
 61	chacha_init_consts(state);
 62	state[4]  = key[0];
 63	state[5]  = key[1];
 64	state[6]  = key[2];
 65	state[7]  = key[3];
 66	state[8]  = key[4];
 67	state[9]  = key[5];
 68	state[10] = key[6];
 69	state[11] = key[7];
 70	state[12] = get_unaligned_le32(iv +  0);
 71	state[13] = get_unaligned_le32(iv +  4);
 72	state[14] = get_unaligned_le32(iv +  8);
 73	state[15] = get_unaligned_le32(iv + 12);
 74}
 75
 76static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
 77{
 78	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
 79		chacha_init_arch(state, key, iv);
 80	else
 81		chacha_init_generic(state, key, iv);
 82}
 83
 84void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
 85		       unsigned int bytes, int nrounds);
 86void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
 87			  unsigned int bytes, int nrounds);
 88
 89static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
 90				unsigned int bytes, int nrounds)
 91{
 92	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
 93		chacha_crypt_arch(state, dst, src, bytes, nrounds);
 94	else
 95		chacha_crypt_generic(state, dst, src, bytes, nrounds);
 96}
 97
 98static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
 99				  unsigned int bytes)
100{
101	chacha_crypt(state, dst, src, bytes, 20);
102}
103
104#endif /* _CRYPTO_CHACHA_H */