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xts128.c: minor optimization.

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This commit is contained in:
Andy Polyakov 2011-03-04 13:17:19 +00:00
parent 0ab8fd58e1
commit 16cb0d9591
1 changed files with 56 additions and 57 deletions
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113
crypto/modes/xts128.c
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@ -69,6 +69,7 @@ int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, u64 secno,
{
const union { long one; char little; } is_endian = {1};
union { u64 u[2]; u32 d[4]; u8 c[16]; } tweak, scratch;
unsigned int i;
if (len<16) return -1;
@ -84,7 +85,7 @@ int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, u64 secno,
(*ctx->block2)(tweak.c,tweak.c,ctx->key2);
if (!enc && len%16) len-=16;
if (!enc && (len%16)) len-=16;
while (len>=16) {
#if defined(STRICT_ALIGNMENT)
@ -103,6 +104,8 @@ int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, u64 secno,
out += 16;
len -= 16;
if (len==0) return 0;
if (is_endian.little) {
unsigned int carry,res;
@ -112,7 +115,7 @@ int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, u64 secno,
tweak.u[1] = (tweak.u[1]<<1)|carry;
}
else {
unsigned int carry,c,i;
unsigned int carry,c;
for (carry=0,i=0;i<16;++i) {
c = tweak.c[i];
@ -122,67 +125,63 @@ int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, u64 secno,
tweak.c[0] ^= 0x87&(0-carry);
}
}
if (len) {
unsigned int i;
if (enc) {
for (i=0;i<len;++i) {
u8 c = inp[i];
out[i] = scratch.c[i];
scratch.c[i] = c;
}
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
memcpy(out-16,scratch.c,16);
}
else {
union { u64 u[2]; u8 c[16]; } tweak1;
if (enc) {
for (i=0;i<len;++i) {
u8 c = inp[i];
out[i] = scratch.c[i];
scratch.c[i] = c;
}
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
memcpy(out-16,scratch.c,16);
if (is_endian.little) {
unsigned int carry,res;
res = 0x87&(((int)tweak.d[3])>>31);
carry = tweak.u[0]>>63;
tweak1.u[0] = (tweak.u[0]<<1)^res;
tweak1.u[1] = (tweak.u[1]<<1)|carry;
}
else {
union { u64 u[2]; u8 c[16]; } tweak1;
unsigned int carry,c;
if (is_endian.little) {
unsigned int carry,res;
res = 0x87&(((int)tweak.d[3])>>31);
carry = tweak.u[0]>>63;
tweak1.u[0] = (tweak.u[0]<<1)^res;
tweak1.u[1] = (tweak.u[1]<<1)|carry;
for (carry=0,i=0;i<16;++i) {
c = tweak.c[i];
tweak1.c[i] = (c<<1)|carry;
carry = c>>7;
}
else {
unsigned int carry,c;
for (carry=0,i=0;i<16;++i) {
c = tweak.c[i];
tweak1.c[i] = (c<<1)|carry;
carry = c>>7;
}
tweak1.c[0] ^= 0x87&(0-carry);
}
#if defined(STRICT_ALIGNMENT)
memcpy(scratch.c,inp,16);
scratch.u[0] ^= tweak1.u[0];
scratch.u[1] ^= tweak1.u[1];
#else
scratch.u[0] = ((u64*)inp)[0]^tweak1.u[0];
scratch.u[1] = ((u64*)inp)[1]^tweak1.u[1];
#endif
(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
scratch.u[0] ^= tweak1.u[0];
scratch.u[1] ^= tweak1.u[1];
for (i=0;i<len;++i) {
u8 c = inp[16+i];
out[16+i] = scratch.c[i];
scratch.c[i] = c;
}
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
memcpy (out,scratch.c,16);
tweak1.c[0] ^= 0x87&(0-carry);
}
#if defined(STRICT_ALIGNMENT)
memcpy(scratch.c,inp,16);
scratch.u[0] ^= tweak1.u[0];
scratch.u[1] ^= tweak1.u[1];
#else
scratch.u[0] = ((u64*)inp)[0]^tweak1.u[0];
scratch.u[1] = ((u64*)inp)[1]^tweak1.u[1];
#endif
(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
scratch.u[0] ^= tweak1.u[0];
scratch.u[1] ^= tweak1.u[1];
for (i=0;i<len;++i) {
u8 c = inp[16+i];
out[16+i] = scratch.c[i];
scratch.c[i] = c;
}
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
(*ctx->block1)(scratch.c,scratch.c,ctx->key1);
scratch.u[0] ^= tweak.u[0];
scratch.u[1] ^= tweak.u[1];
memcpy (out,scratch.c,16);
}
return 0;