ref: 673e3de9a2f59dbac9a845b2f28363b2bb9f0041
dir: /libsec/aes_xts.c/
// Author Taru Karttunen <[email protected]> // This file can be used as both Public Domain or Creative Commons CC0. #include <u.h> #include <libc.h> #include <libsec.h> #define AesBlockSize 16 static void xor128(uchar* o,uchar* i1,uchar* i2) { ((ulong*)o)[0] = ((ulong*)i1)[0] ^ ((ulong*)i2)[0]; ((ulong*)o)[1] = ((ulong*)i1)[1] ^ ((ulong*)i2)[1]; ((ulong*)o)[2] = ((ulong*)i1)[2] ^ ((ulong*)i2)[2]; ((ulong*)o)[3] = ((ulong*)i1)[3] ^ ((ulong*)i2)[3]; } static void gf_mulx(uchar* x) { ulong t = ((((ulong*)(x))[3] & 0x80000000u) ? 0x00000087u : 0);; ((ulong*)(x))[3] = (((ulong*)(x))[3] << 1) | (((ulong*)(x))[2] & 0x80000000u ? 1 : 0); ((ulong*)(x))[2] = (((ulong*)(x))[2] << 1) | (((ulong*)(x))[1] & 0x80000000u ? 1 : 0); ((ulong*)(x))[1] = (((ulong*)(x))[1] << 1) | (((ulong*)(x))[0] & 0x80000000u ? 1 : 0); ((ulong*)(x))[0] = (((ulong*)(x))[0] << 1) ^ t; } int aes_xts_encrypt(ulong tweak[], ulong ecb[], vlong sectorNumber, uchar *input, uchar *output, ulong len) { uchar T[16], x[16]; int i; if(len % 16 != 0) return -1; for(i=0; i<AesBlockSize; i++) { T[i] = (uchar)(sectorNumber & 0xFF); sectorNumber = sectorNumber >> 8; } aes_encrypt(tweak, 10, T, T); for (i=0; i<len; i+=AesBlockSize) { xor128(&x[0], &input[i], &T[0]); aes_encrypt(ecb, 10, x, x); xor128(&output[i], &x[0], &T[0]); gf_mulx(&T[0]); } return 0; } int aes_xts_decrypt(ulong tweak[], ulong ecb[], vlong sectorNumber, uchar *input, uchar *output, ulong len) { uchar T[16], x[16]; int i; if(len % 16 != 0) return -1; for(i=0; i<AesBlockSize; i++) { T[i] = (uchar)(sectorNumber & 0xFF); sectorNumber = sectorNumber >> 8; } aes_encrypt(tweak, 10, T, T); for (i=0; i<len; i+=AesBlockSize) { xor128(&x[0], &input[i], &T[0]); aes_decrypt(ecb, 10, x, x); xor128(&output[i], &x[0], &T[0]); gf_mulx(&T[0]); } return 0; }