diff options
Diffstat (limited to 'src/crypto')
| -rw-r--r-- | src/crypto/slow-hash.c | 73 |
1 files changed, 63 insertions, 10 deletions
diff --git a/src/crypto/slow-hash.c b/src/crypto/slow-hash.c index 46edb0fc1..1d1a3f43e 100644 --- a/src/crypto/slow-hash.c +++ b/src/crypto/slow-hash.c @@ -103,8 +103,16 @@ j = state_index(a); \ _c = _mm_load_si128(R128(&hp_state[j])); \ _a = _mm_load_si128(R128(a)); \ - -// dga's optimized scratchpad twiddling + +/* + * An SSE-optimized implementation of the second half of CryptoNote step 3. + * After using AES to mix a scratchpad value into _c (done by the caller), + * this macro xors it with _b and stores the result back to the same index (j) that it + * loaded the scratchpad value from. It then performs a second random memory + * read/write from the scratchpad, but this time mixes the values using a 64 + * bit multiply. + * This code is based upon an optimized implementation by dga. + */ #define post_aes() \ _mm_store_si128(R128(c), _c); \ _b = _mm_xor_si128(_b, _c); \ @@ -160,6 +168,10 @@ void cpuid(int CPUInfo[4], int InfoType) } #endif +/** + * @brief a = (a xor b), where a and b point to 128 bit values + */ + STATIC INLINE void xor_blocks(uint8_t *a, const uint8_t *b) { U64(a)[0] ^= U64(b)[0]; @@ -218,7 +230,12 @@ STATIC INLINE void aes_256_assist2(__m128i* t1, __m128i * t3) * of the AES encryption used to fill (and later, extract randomness from) * the large 2MB buffer. Note that CryptoNight does not use a completely * standard AES encryption for its buffer expansion, so do not copy this - * function outside of Monero without caution! + * function outside of Monero without caution! This version uses the hardware + * AESKEYGENASSIST instruction to speed key generation, and thus requires + * CPU AES support. + * For more information about these functions, see page 19 of Intel's AES instructions + * white paper: + * http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/aes-instructions-set-white-paper.pdf * * @param key the input 128 bit key * @param expandedKey An output buffer to hold the generated key schedule @@ -274,6 +291,8 @@ STATIC INLINE void aes_expand_key(const uint8_t *key, uint8_t *expandedKey) * in subsequent steps by aesenc_si128), and it does not use the simpler final round. * Hence, this is a "pseudo" round - though the function actually implements 10 rounds together. * + * Note that unlike aesb_pseudo_round, this function works on multiple data chunks. + * * @param in a pointer to nblocks * 128 bits of data to be encrypted * @param out a pointer to an nblocks * 128 bit buffer where the output will be stored * @param expandedKey the expanded AES key @@ -304,6 +323,20 @@ STATIC INLINE void aes_pseudo_round(const uint8_t *in, uint8_t *out, } } +/* + * @brief aes_pseudo_round that loads data from *in and xors it with *xor first + * + * This function performs the same operations as aes_pseudo_round, but before + * performing the encryption of each 128 bit block from <in>, it xors + * it with the corresponding block from <xor>. + * + * @param in a pointer to nblocks * 128 bits of data to be encrypted + * @param out a pointer to an nblocks * 128 bit buffer where the output will be stored + * @param expandedKey the expanded AES key + * @param xor a pointer to an nblocks * 128 bit buffer that is xored into in before encryption (in is left unmodified) + * @param nblocks the number of 128 blocks of data to be encrypted + */ + STATIC INLINE void aes_pseudo_round_xor(const uint8_t *in, uint8_t *out, const uint8_t *expandedKey, const uint8_t *xor, int nblocks) { @@ -362,6 +395,18 @@ BOOL SetLockPagesPrivilege(HANDLE hProcess, BOOL bEnable) } #endif +/** + * @brief allocate the 2MB scratch buffer using OS support for huge pages, if available + * + * This function tries to allocate the 2MB scratch buffer using a single + * 2MB "huge page" (instead of the usual 4KB page sizes) to reduce TLB misses + * during the random accesses to the scratch buffer. This is one of the + * important speed optimizations needed to make CryptoNight faster. + * + * No parameters. Updates a thread-local pointer, hp_state, to point to + * the allocated buffer. + */ + void slow_hash_allocate_state(void) { int state = 0; @@ -391,6 +436,10 @@ void slow_hash_allocate_state(void) } } +/** + *@brief frees the state allocated by slow_hash_allocate_state + */ + void slow_hash_free_state(void) { if(hp_state == NULL) @@ -434,9 +483,12 @@ void slow_hash_free_state(void) * core on 2013-era CPUs. When available, this implementation will use hardware * AES support on x86 CPUs. * + * A diagram of the inner loop of this function can be found at + * http://www.cs.cmu.edu/~dga/crypto/xmr/cryptonight.png + * * @param data the data to hash * @param length the length in bytes of the data - * @param hash a pointer to a buffer in which the final hash will be stored + * @param hash a pointer to a buffer in which the final 256 bit hash will be stored */ void cn_slow_hash(const void *data, size_t length, char *hash) @@ -507,14 +559,14 @@ void cn_slow_hash(const void *data, size_t length, char *hash) */ _b = _mm_load_si128(R128(b)); - // this is ugly but the branching affects the loop somewhat so put it outside. + // Two independent versions, one with AES, one without, this to ensure that + // the useAes test is only performed once, not every iteration. if(useAes) { for(i = 0; i < ITER / 2; i++) { pre_aes(); _c = _mm_aesenc_si128(_c, _a); - // post_aes(), optimized scratchpad twiddling (credits to dga) post_aes(); } } @@ -556,10 +608,11 @@ void cn_slow_hash(const void *data, size_t length, char *hash) oaes_free((OAES_CTX **) &aes_ctx); } - /* CryptoNight Step 5: Use the resulting data to select which of four - * finalizer hash functions to apply to the data (Blake, Groestl, JH, or Skein). - * Use this hash to squeeze the 200 byte pseudorandom state array down - * to the final hash output. + /* CryptoNight Step 5: Apply Keccak to the state again, and then + * use the resulting data to select which of four finalizer + * hash functions to apply to the data (Blake, Groestl, JH, or Skein). + * Use this hash to squeeze the state array down + * to the final 256 bit hash output. */ memcpy(state.init, text, INIT_SIZE_BYTE); |