From c021390e218066ca01828917dd940dff26ceff3b Mon Sep 17 00:00:00 2001 From: cinap_lenrek Date: Sun, 29 Oct 2017 21:49:24 +0100 Subject: [PATCH] libsec: rewrite aex_xts_encrypt()/aes_xts_decrypt() the previous implementation was not portable at all, assuming little endian in gf_mulx() and that one can cast unaligned pointers to ulong in xor128(). also the error code is likely to be ignored, so better abort() when the length is not a multiple of the AES block size. we also pass in full AESstate structures now instead of the expanded key longs, so that we do not need to hardcode the number of rounds. this allows each indiviaul keys to be bigger than 128 bit. --- sys/include/ape/libsec.h | 4 +- sys/include/libsec.h | 4 +- sys/src/libsec/port/aes_xts.c | 129 +++++++++++++++++++--------------- 3 files changed, 75 insertions(+), 62 deletions(-) diff --git a/sys/include/ape/libsec.h b/sys/include/ape/libsec.h index 232d89524..58e081891 100644 --- a/sys/include/ape/libsec.h +++ b/sys/include/ape/libsec.h @@ -509,8 +509,8 @@ uchar *readcert(char *filename, int *pcertlen); PEMChain*readcertchain(char *filename); /* aes_xts.c */ -int aes_xts_encrypt(ulong tweak[], ulong ecb[], uvlong sectorNumber, uchar *input, uchar *output, ulong len) ; -int aes_xts_decrypt(ulong tweak[], ulong ecb[], uvlong sectorNumber, uchar *input, uchar *output, ulong len); +void aes_xts_encrypt(AESstate *tweak, AESstate *ecb, uvlong sectorNumber, uchar *input, uchar *output, ulong len); +void aes_xts_decrypt(AESstate *tweak, AESstate *ecb, uvlong sectorNumber, uchar *input, uchar *output, ulong len); typedef struct ECpoint{ int inf; diff --git a/sys/include/libsec.h b/sys/include/libsec.h index 2f19ce36e..ccf5f24f3 100644 --- a/sys/include/libsec.h +++ b/sys/include/libsec.h @@ -502,8 +502,8 @@ uchar *readcert(char *filename, int *pcertlen); PEMChain*readcertchain(char *filename); /* aes_xts.c */ -int aes_xts_encrypt(ulong tweak[], ulong ecb[], uvlong sectorNumber, uchar *input, uchar *output, ulong len) ; -int aes_xts_decrypt(ulong tweak[], ulong ecb[], uvlong sectorNumber, uchar *input, uchar *output, ulong len); +void aes_xts_encrypt(AESstate *tweak, AESstate *ecb, uvlong sectorNumber, uchar *input, uchar *output, ulong len); +void aes_xts_decrypt(AESstate *tweak, AESstate *ecb, uvlong sectorNumber, uchar *input, uchar *output, ulong len); typedef struct ECpoint{ int inf; diff --git a/sys/src/libsec/port/aes_xts.c b/sys/src/libsec/port/aes_xts.c index 1ae8d107a..7236859f9 100644 --- a/sys/src/libsec/port/aes_xts.c +++ b/sys/src/libsec/port/aes_xts.c @@ -1,70 +1,83 @@ -// Author Taru Karttunen -// This file can be used as both Public Domain or Creative Commons CC0. #include "os.h" #include +/* little-endian data order */ +#define GET4(p) ((p)[0]|((p)[1]<<8)|((p)[2]<<16)|((p)[3]<<24)) +#define PUT4(p,v) (p)[0]=(v);(p)[1]=(v)>>8;(p)[2]=(v)>>16;(p)[3]=(v)>>24 + 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]; +gf_mulx(uchar *x) +{ + ulong t0, t1, t2, t3, t4; + + t0 = GET4(x); + t1 = GET4(x+4); + t2 = GET4(x+8); + t3 = GET4(x+12); + + t4 = (t3 >> 31); + t3 = (t3 << 1) | (t2 >> 31); + t2 = (t2 << 1) | (t1 >> 31); + t1 = (t1 << 1) | (t0 >> 31); + t0 = (t0 << 1) ^ (t4*135); + + PUT4(x, t0); + PUT4(x+4, t1); + PUT4(x+8, t2); + PUT4(x+12, t3); } 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[], uvlong sectorNumber, uchar *input, uchar *output, ulong len) { - uchar T[16], x[16]; +xor128(uchar *o, uchar *i1, uchar *i2) +{ int i; - - if(len % 16 != 0) - return -1; - for(i=0; i> 8; - } - - aes_encrypt(tweak, 10, T, T); - - for (i=0; i> 8; - } - - aes_encrypt(tweak, 10, T, T); - - for (i=0; i>= 32; + PUT4(T+4, (ulong)sectorNumber); + PUT4(T+8, 0); + PUT4(T+12, 0); + aes_encrypt(tweak->ekey, tweak->rounds, T, T); +} + +void +aes_xts_encrypt(AESstate *tweak, AESstate *ecb, + uvlong sectorNumber, uchar *input, uchar *output, ulong len) +{ + uchar T[AESbsize], x[AESbsize]; + + if(len % AESbsize) + abort(); + + setupT(tweak, sectorNumber, T); + for (; len > 0; len -= AESbsize, input += AESbsize, output += AESbsize) { + xor128(x, input, T); + aes_encrypt(ecb->ekey, ecb->rounds, x, x); + xor128(output, x, T); + gf_mulx(T); + } +} + +void +aes_xts_decrypt(AESstate *tweak, AESstate *ecb, + uvlong sectorNumber, uchar *input, uchar *output, ulong len) +{ + uchar T[AESbsize], x[AESbsize]; + + if(len % AESbsize) + abort(); + + setupT(tweak, sectorNumber, T); + for (; len > 0; len -= AESbsize, input += AESbsize, output += AESbsize) { + xor128(x, input, T); + aes_decrypt(ecb->dkey, ecb->rounds, x, x); + xor128(output, x, T); + gf_mulx(T); + } }