Line data    Source code

       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             : 
      33             : void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
      34             : static inline void chacha20_block(u32 *state, u8 *stream)
      35             : {
      36         200 :         chacha_block_generic(state, stream, 20);
      37             : }
      38             : 
      39             : void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
      40             : void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
      41             : 
      42             : static 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             : 
      50             : enum chacha_constants { /* expand 32-byte k */
      51             :         CHACHA_CONSTANT_EXPA = 0x61707865U,
      52             :         CHACHA_CONSTANT_ND_3 = 0x3320646eU,
      53             :         CHACHA_CONSTANT_2_BY = 0x79622d32U,
      54             :         CHACHA_CONSTANT_TE_K = 0x6b206574U
      55             : };
      56             : 
      57             : static inline void chacha_init_consts(u32 *state)
      58             : {
      59          69 :         state[0]  = CHACHA_CONSTANT_EXPA;
      60          69 :         state[1]  = CHACHA_CONSTANT_ND_3;
      61          69 :         state[2]  = CHACHA_CONSTANT_2_BY;
      62          69 :         state[3]  = CHACHA_CONSTANT_TE_K;
      63             : }
      64             : 
      65             : void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
      66             : static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
      67             : {
      68             :         chacha_init_consts(state);
      69             :         state[4]  = key[0];
      70             :         state[5]  = key[1];
      71             :         state[6]  = key[2];
      72             :         state[7]  = key[3];
      73             :         state[8]  = key[4];
      74             :         state[9]  = key[5];
      75             :         state[10] = key[6];
      76             :         state[11] = key[7];
      77             :         state[12] = get_unaligned_le32(iv +  0);
      78             :         state[13] = get_unaligned_le32(iv +  4);
      79             :         state[14] = get_unaligned_le32(iv +  8);
      80             :         state[15] = get_unaligned_le32(iv + 12);
      81             : }
      82             : 
      83             : static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
      84             : {
      85             :         if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
      86             :                 chacha_init_arch(state, key, iv);
      87             :         else
      88             :                 chacha_init_generic(state, key, iv);
      89             : }
      90             : 
      91             : void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
      92             :                        unsigned int bytes, int nrounds);
      93             : void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
      94             :                           unsigned int bytes, int nrounds);
      95             : 
      96             : static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
      97             :                                 unsigned int bytes, int nrounds)
      98             : {
      99             :         if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
     100             :                 chacha_crypt_arch(state, dst, src, bytes, nrounds);
     101             :         else
     102             :                 chacha_crypt_generic(state, dst, src, bytes, nrounds);
     103             : }
     104             : 
     105             : static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
     106             :                                   unsigned int bytes)
     107             : {
     108             :         chacha_crypt(state, dst, src, bytes, 20);
     109             : }
     110             : 
     111             : #endif /* _CRYPTO_CHACHA_H */