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RC4 tune-up featuring 30-40% performance improvement on most RISC

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platforms. See crypto/rc4/rc4_enc.c for further details.
This commit is contained in:
Andy Polyakov
1999-10-07 12:03:59 +00:00
parent def38e38ec
commit 2dae04d038
4 changed files with 242 additions and 125 deletions
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16
crypto/opensslconf.h.in
View File

@@ -25,11 +25,25 @@
#define RC2_INT unsigned int
#endif
#if defined(HEADER_RC4_H) && !defined(RC4_INT)
#if defined(HEADER_RC4_H)
#if !defined(RC4_INT)
/* using int types make the structure larger but make the code faster
* on most boxes I have tested - up to %20 faster. */
/*
* I don't know what does "most" mean, but declaring "int" is a must on:
* - Intel P6 because partial register stalls are very expensive;
* - elder Alpha because it lacks byte load/store instructions;
*/
#define RC4_INT unsigned int
#endif
#if !defined(RC4_CHUNK)
/*
* This enables code handling data aligned at natural CPU word
* boundary. See crypto/rc4/rc4_enc.c for further details.
*/
#undef RC4_CHUNK
#endif
#endif
#if defined(HEADER_DES_H) && !defined(DES_LONG)
/* If this is set to 'unsigned int' on a DEC Alpha, this gives about a

216
crypto/rc4/rc4_enc.c
View File

@@ -78,7 +78,7 @@ void RC4(RC4_KEY *key, unsigned long len, unsigned char *indata,
y=key->y;
d=key->data;
#if defined(RC4_CHUNK) && (defined(L_ENDIAN) || defined(B_ENDIAN))
#if defined(RC4_CHUNK)
/*
* The original reason for implementing this(*) was the fact that
* pre-21164a Alpha CPUs don't have byte load/store instructions
@@ -87,21 +87,30 @@ void RC4(RC4_KEY *key, unsigned long len, unsigned char *indata,
* at natural word size made it possible to reduce amount of
* instructions as well as to perform early read-ahead without
* suffering from RAW (read-after-write) hazard. This resulted
* in >40%(**) performance improvement (on 21064 box with gcc).
* in ~40%(**) performance improvement on 21064 box with gcc.
* But it's not only Alpha users who win here:-) Thanks to the
* early-n-wide read-ahead this implementation also exhibits
* >40% speed-up on SPARC and almost 20% on MIPS.
* >40% speed-up on SPARC and 20-30% on 64-bit MIPS (depending
* on sizeof(RC4_INT)).
*
* (*) "this" means code which recognizes the case when input
* and output pointers appear to be aligned at natural CPU
* word boundary.
* word boundary
* (**) i.e. according to 'apps/openssl speed rc4' benchmark,
* crypto/rc4/rc4speed.c exhibits almost 70% speed-up.
* crypto/rc4/rc4speed.c exhibits almost 70% speed-up...
*
* Cavets.
*
* - RC4_CHUNK="unsigned long long" should be a #1 choice for
* UltraSPARC. Unfortunately gcc generates very slow code
* (2.5-3 times slower than one generated by Sun's WorkShop
* C) and therefore gcc (at least 2.95 and earlier) should
* always be told that RC4_CHUNK="unsigned long".
*
* <appro@fy.chalmers.se>
*/
#define RC4_STEP ( \
# define RC4_STEP ( \
x=(x+1) &0xff, \
tx=d[x], \
y=(tx+y)&0xff, \
@@ -111,70 +120,148 @@ void RC4(RC4_KEY *key, unsigned long len, unsigned char *indata,
(RC4_CHUNK)d[(tx+ty)&0xff]\
)
#if defined(L_ENDIAN)
# define SHFT(c) ((c)*8)
# define MASK(i) (((RC4_CHUNK)-1)>>((sizeof(RC4_CHUNK)-(i))<<3))
# define SHINC 8
#elif defined(B_ENDIAN)
# define SHFT(c) ((sizeof(RC4_CHUNK)-(c)-1)*8)
# define MASK(i) (((RC4_CHUNK)-1)<<((sizeof(RC4_CHUNK)-(i))<<3))
# define SHINC -8
#else
# error "L_ENDIAN or B_ENDIAN *must* be defined!"
#endif
if ( ( ((unsigned long)indata & (sizeof(RC4_CHUNK)-1)) |
((unsigned long)outdata & (sizeof(RC4_CHUNK)-1)) ) == 0
) {
RC4_CHUNK ichunk,cipher;
((unsigned long)outdata & (sizeof(RC4_CHUNK)-1)) ) == 0 )
{
RC4_CHUNK ichunk,otp;
const union { long one; char little; } is_endian = {1};
for (;len&-sizeof(RC4_CHUNK);len-=sizeof(RC4_CHUNK)) {
ichunk = *(RC4_CHUNK *)indata;
cipher = RC4_STEP<<SHFT(0);
cipher |= RC4_STEP<<SHFT(1);
cipher |= RC4_STEP<<SHFT(2);
cipher |= RC4_STEP<<SHFT(3);
#ifdef RC4_CHUNK_IS_64_BIT
cipher |= RC4_STEP<<SHFT(4);
cipher |= RC4_STEP<<SHFT(5);
cipher |= RC4_STEP<<SHFT(6);
cipher |= RC4_STEP<<SHFT(7);
#endif
*(RC4_CHUNK *)outdata = cipher^ichunk;
indata += sizeof(RC4_CHUNK);
outdata += sizeof(RC4_CHUNK);
}
if (len) {
RC4_CHUNK mask,ochunk;
/*
* I reckon we can afford to implement both endian
* cases and to decide which way to take at run-time
* because the machine code appears to be very compact
* and redundant 1-2KB is perfectly tolerable (i.e.
* in case the compiler fails to eliminate it:-). By
* suggestion from Terrel Larson <terr@terralogic.net>
* who also stands for the is_endian union:-)
*
* Special notes.
*
* - is_endian is declared automatic as doing otherwise
* (declaring static) prevents gcc from eliminating
* the redundant code;
* - compilers (those I've tried) don't seem to have
* problems eliminating either the operators guarded
* by "if (sizeof(RC4_CHUNK)==8)" or the condition
* expressions themselves so I've got 'em to replace
* corresponding #ifdefs from the previous version;
* - I chose to let the redundant switch cases when
* sizeof(RC4_CHUNK)!=8 be (were also #ifdefed
* before);
* - in case you wonder "&(sizeof(RC4_CHUNK)*8-1)" in
* [LB]ESHFT guards against "shift is out of range"
* warnings when sizeof(RC4_CHUNK)!=8
*
* <appro@fy.chalmers.se>
*/
if (!is_endian.little)
{ /* BIG-ENDIAN CASE */
# define BESHFT(c) (((sizeof(RC4_CHUNK)-(c)-1)*8)&(sizeof(RC4_CHUNK)*8-1))
for (;len&-sizeof(RC4_CHUNK);len-=sizeof(RC4_CHUNK))
{
ichunk = *(RC4_CHUNK *)indata;
otp = RC4_STEP<<BESHFT(0);
otp |= RC4_STEP<<BESHFT(1);
otp |= RC4_STEP<<BESHFT(2);
otp |= RC4_STEP<<BESHFT(3);
if (sizeof(RC4_CHUNK)==8)
{
otp |= RC4_STEP<<BESHFT(4);
otp |= RC4_STEP<<BESHFT(5);
otp |= RC4_STEP<<BESHFT(6);
otp |= RC4_STEP<<BESHFT(7);
}
*(RC4_CHUNK *)outdata = otp^ichunk;
indata += sizeof(RC4_CHUNK);
outdata += sizeof(RC4_CHUNK);
}
if (len)
{
RC4_CHUNK mask=(RC4_CHUNK)-1, ochunk;
ichunk = *(RC4_CHUNK *)indata;
ochunk = *(RC4_CHUNK *)outdata;
cipher = 0;
i = SHFT(0);
mask = MASK(len);
switch (len) {
#ifdef RC4_CHUNK_IS_64_BIT
case 7: cipher = RC4_STEP<<SHFT(0), i+=SHINC;
case 6: cipher |= RC4_STEP<<i, i+=SHINC;
case 5: cipher |= RC4_STEP<<i, i+=SHINC;
case 4: cipher |= RC4_STEP<<i, i+=SHINC;
case 3: cipher |= RC4_STEP<<i, i+=SHINC;
#else
case 3: cipher = RC4_STEP<<SHFT(0), i+=SHINC;
#endif
case 2: cipher |= RC4_STEP<<i, i+=SHINC;
case 1: cipher |= RC4_STEP<<i, i+=SHINC;
case 0: ; /* it's never the case, but it
has to be here for ultrix? */
ichunk = *(RC4_CHUNK *)indata;
ochunk = *(RC4_CHUNK *)outdata;
otp = 0;
i = BESHFT(0);
mask <<= (sizeof(RC4_CHUNK)-len)<<3;
switch (len&(sizeof(RC4_CHUNK)-1))
{
case 7: otp = RC4_STEP<<i, i-=8;
case 6: otp |= RC4_STEP<<i, i-=8;
case 5: otp |= RC4_STEP<<i, i-=8;
case 4: otp |= RC4_STEP<<i, i-=8;
case 3: otp |= RC4_STEP<<i, i-=8;
case 2: otp |= RC4_STEP<<i, i-=8;
case 1: otp |= RC4_STEP<<i, i-=8;
case 0: ; /*
* it's never the case,
* but it has to be here
* for ultrix?
*/
}
ochunk &= ~mask;
ochunk |= (otp^ichunk) & mask;
*(RC4_CHUNK *)outdata = ochunk;
}
key->x=x;
key->y=y;
return;
}
else
{ /* LITTLE-ENDIAN CASE */
# define LESHFT(c) (((c)*8)&(sizeof(RC4_CHUNK)*8-1))
for (;len&-sizeof(RC4_CHUNK);len-=sizeof(RC4_CHUNK))
{
ichunk = *(RC4_CHUNK *)indata;
otp = RC4_STEP;
otp |= RC4_STEP<<8;
otp |= RC4_STEP<<16;
otp |= RC4_STEP<<24;
if (sizeof(RC4_CHUNK)==8)
{
otp |= RC4_STEP<<LESHFT(4);
otp |= RC4_STEP<<LESHFT(5);
otp |= RC4_STEP<<LESHFT(6);
otp |= RC4_STEP<<LESHFT(7);
}
*(RC4_CHUNK *)outdata = otp^ichunk;
indata += sizeof(RC4_CHUNK);
outdata += sizeof(RC4_CHUNK);
}
if (len)
{
RC4_CHUNK mask=(RC4_CHUNK)-1, ochunk;
ichunk = *(RC4_CHUNK *)indata;
ochunk = *(RC4_CHUNK *)outdata;
otp = 0;
i = 0;
mask >>= (sizeof(RC4_CHUNK)-len)<<3;
switch (len&(sizeof(RC4_CHUNK)-1))
{
case 7: otp = RC4_STEP, i+=8;
case 6: otp |= RC4_STEP<<i, i+=8;
case 5: otp |= RC4_STEP<<i, i+=8;
case 4: otp |= RC4_STEP<<i, i+=8;
case 3: otp |= RC4_STEP<<i, i+=8;
case 2: otp |= RC4_STEP<<i, i+=8;
case 1: otp |= RC4_STEP<<i, i+=8;
case 0: ; /*
* it's never the case,
* but it has to be here
* for ultrix?
*/
}
ochunk &= ~mask;
ochunk |= (otp^ichunk) & mask;
*(RC4_CHUNK *)outdata = ochunk;
}
key->x=x;
key->y=y;
return;
}
ochunk &= ~mask;
ochunk |= (cipher^ichunk) & mask;
*(RC4_CHUNK *)outdata = ochunk;
}
}
else
#endif
{
#define LOOP(in,out) \
x=((x+1)&0xff); \
tx=d[x]; \
@@ -223,7 +310,6 @@ void RC4(RC4_KEY *key, unsigned long len, unsigned char *indata,
RC4_LOOP(indata,outdata,6); if (--i == 0) break;
}
}
}
key->x=x;
key->y=y;
}