03569bc50f
function old new delta xorbuf_aligned_AES_BLOCK_SIZE - 23 +23 xwrite_encrypted 585 580 -5 aesgcm_GHASH 233 228 -5 GMULT 192 187 -5 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 0/3 up/down: 23/-15) Total: 8 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
142 lines
3.8 KiB
C
142 lines
3.8 KiB
C
/*
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* Copyright (C) 2018 Denys Vlasenko
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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#include "tls.h"
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typedef uint8_t byte;
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typedef uint32_t word32;
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#define XMEMSET memset
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#define XMEMCPY memcpy
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/* from wolfssl-3.15.3/wolfcrypt/src/aes.c */
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static ALWAYS_INLINE void FlattenSzInBits(byte* buf, word32 sz)
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{
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/* Multiply the sz by 8 */
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//bbox: these sizes are never even close to 2^32/8
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// word32 szHi = (sz >> (8*sizeof(sz) - 3));
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sz <<= 3;
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/* copy over the words of the sz into the destination buffer */
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// buf[0] = (szHi >> 24) & 0xff;
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// buf[1] = (szHi >> 16) & 0xff;
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// buf[2] = (szHi >> 8) & 0xff;
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// buf[3] = szHi & 0xff;
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*(uint32_t*)(buf + 0) = 0;
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// buf[4] = (sz >> 24) & 0xff;
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// buf[5] = (sz >> 16) & 0xff;
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// buf[6] = (sz >> 8) & 0xff;
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// buf[7] = sz & 0xff;
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*(uint32_t*)(buf + 4) = SWAP_BE32(sz);
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}
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static void RIGHTSHIFTX(byte* x)
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{
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int i;
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int carryOut = 0;
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int carryIn = 0;
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int borrow = x[15] & 0x01;
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for (i = 0; i < AES_BLOCK_SIZE; i++) {
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carryOut = x[i] & 0x01;
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x[i] = (x[i] >> 1) | (carryIn ? 0x80 : 0);
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carryIn = carryOut;
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}
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if (borrow) x[0] ^= 0xE1;
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}
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static void GMULT(byte* X, byte* Y)
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{
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byte Z[AES_BLOCK_SIZE] ALIGNED_long;
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byte V[AES_BLOCK_SIZE] ALIGNED_long;
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int i, j;
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XMEMSET(Z, 0, AES_BLOCK_SIZE);
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XMEMCPY(V, X, AES_BLOCK_SIZE);
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for (i = 0; i < AES_BLOCK_SIZE; i++)
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{
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byte y = Y[i];
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for (j = 0; j < 8; j++)
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{
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if (y & 0x80) {
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xorbuf_aligned_AES_BLOCK_SIZE(Z, V);
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}
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RIGHTSHIFTX(V);
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y = y << 1;
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}
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}
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XMEMCPY(X, Z, AES_BLOCK_SIZE);
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}
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//bbox:
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// for TLS AES-GCM, a (which is AAD) is always 13 bytes long, and bbox code provides
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// extra 3 zeroed bytes, making it a[16], or a[AES_BLOCK_SIZE].
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// Resulting auth tag in s[] is also always AES_BLOCK_SIZE bytes.
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//
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// This allows some simplifications.
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#define aSz 13
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#define sSz AES_BLOCK_SIZE
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void FAST_FUNC aesgcm_GHASH(byte* h,
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const byte* a, //unsigned aSz,
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const byte* c, unsigned cSz,
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byte* s //, unsigned sSz
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)
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{
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byte x[AES_BLOCK_SIZE] ALIGNED_long;
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byte scratch[AES_BLOCK_SIZE] ALIGNED_long;
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word32 blocks, partial;
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//was: byte* h = aes->H;
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//XMEMSET(x, 0, AES_BLOCK_SIZE);
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/* Hash in A, the Additional Authentication Data */
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// if (aSz != 0 && a != NULL) {
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// blocks = aSz / AES_BLOCK_SIZE;
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// partial = aSz % AES_BLOCK_SIZE;
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// while (blocks--) {
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//xorbuf(x, a, AES_BLOCK_SIZE);
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XMEMCPY(x, a, AES_BLOCK_SIZE);// memcpy(x,a) = memset(x,0)+xorbuf(x,a)
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GMULT(x, h);
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// a += AES_BLOCK_SIZE;
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// }
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// if (partial != 0) {
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// XMEMSET(scratch, 0, AES_BLOCK_SIZE);
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// XMEMCPY(scratch, a, partial);
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// xorbuf(x, scratch, AES_BLOCK_SIZE);
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// GMULT(x, h);
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// }
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// }
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/* Hash in C, the Ciphertext */
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if (cSz != 0 /*&& c != NULL*/) {
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blocks = cSz / AES_BLOCK_SIZE;
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partial = cSz % AES_BLOCK_SIZE;
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while (blocks--) {
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//xorbuf_aligned_AES_BLOCK_SIZE(x, c); - c is not guaranteed to be aligned
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xorbuf(x, c, AES_BLOCK_SIZE);
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GMULT(x, h);
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c += AES_BLOCK_SIZE;
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}
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if (partial != 0) {
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//XMEMSET(scratch, 0, AES_BLOCK_SIZE);
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//XMEMCPY(scratch, c, partial);
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//xorbuf(x, scratch, AES_BLOCK_SIZE);
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xorbuf(x, c, partial);//same result as above
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GMULT(x, h);
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}
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}
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/* Hash in the lengths of A and C in bits */
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FlattenSzInBits(&scratch[0], aSz);
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FlattenSzInBits(&scratch[8], cSz);
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xorbuf_aligned_AES_BLOCK_SIZE(x, scratch);
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GMULT(x, h);
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/* Copy the result into s. */
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XMEMCPY(s, x, sSz);
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}
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