On 6/3/23 06:15, Ard Biesheuvel wrote:
diff --git a/crypto/aes.c b/crypto/aes.c index 1309a13e91..708838315a 100644 --- a/crypto/aes.c +++ b/crypto/aes.c @@ -29,6 +29,7 @@ */ #include "qemu/osdep.h" #include "crypto/aes.h" +#include "crypto/aes-round.h"typedef uint32_t u32; typedef uint8_t u8; @@ -1251,6 +1252,52 @@ static const u32 rcon[] = { 0x1B000000, 0x36000000, /* for 128-bit blocks, Rijndael never uses more than 10 rcon values */ }; +/* Perform SubBytes + ShiftRows. */ +static inline void +aesenc_SB_SR_swap(AESState *r, const AESState *st, bool swap) +{ + const int swap_b = swap ? 15 : 0; + uint8_t t; + + /* These four indexes are not swizzled. */ + r->b[swap_b ^ 0x0] = AES_sbox[st->b[swap_b ^ AES_SH_0]]; + r->b[swap_b ^ 0x4] = AES_sbox[st->b[swap_b ^ AES_SH_4]]; + r->b[swap_b ^ 0x8] = AES_sbox[st->b[swap_b ^ AES_SH_8]]; + r->b[swap_b ^ 0xc] = AES_sbox[st->b[swap_b ^ AES_SH_C]]; + + /* Otherwise, break cycles. */ +This is only needed it r == st, right?
Yes. This is, perhaps, where using symbolic AES_SH_X while assuming knowledge of the value does not aid understanding.
r~
+ t = AES_sbox[st->b[swap_b ^ AES_SH_D]]; + r->b[swap_b ^ 0x1] = AES_sbox[st->b[swap_b ^ AES_SH_1]]; + r->b[swap_b ^ 0x5] = AES_sbox[st->b[swap_b ^ AES_SH_5]]; + r->b[swap_b ^ 0x9] = AES_sbox[st->b[swap_b ^ AES_SH_9]]; + r->b[swap_b ^ 0xd] = t; + + t = AES_sbox[st->b[swap_b ^ AES_SH_A]]; + r->b[swap_b ^ 0x2] = AES_sbox[st->b[swap_b ^ AES_SH_2]]; + r->b[swap_b ^ 0xa] = t; + + t = AES_sbox[st->b[swap_b ^ AES_SH_E]]; + r->b[swap_b ^ 0x6] = AES_sbox[st->b[swap_b ^ AES_SH_6]]; + r->b[swap_b ^ 0xe] = t; + + t = AES_sbox[st->b[swap_b ^ AES_SH_7]]; + r->b[swap_b ^ 0x3] = AES_sbox[st->b[swap_b ^ AES_SH_3]]; + r->b[swap_b ^ 0xf] = AES_sbox[st->b[swap_b ^ AES_SH_F]]; + r->b[swap_b ^ 0xb] = AES_sbox[st->b[swap_b ^ AES_SH_B]]; + r->b[swap_b ^ 0x7] = t; +} + +void aesenc_SB_SR_gen(AESState *r, const AESState *st) +{ + aesenc_SB_SR_swap(r, st, false); +} + +void aesenc_SB_SR_genrev(AESState *r, const AESState *st) +{ + aesenc_SB_SR_swap(r, st, true); +} + /** * Expand the cipher key into the encryption key schedule. */ -- 2.34.1
