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Improve GCM performance by factor 2-3 by shifting full 32/64 bit words

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This commit is contained in:
Martin Willi 2010-08-19 18:49:35 +02:00
parent 1a64981048
commit 23cf96773a
1 changed files with 25 additions and 5 deletions
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30
src/libstrongswan/plugins/gcm/gcm_aead.c
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@ -15,7 +15,7 @@
#include "gcm_aead.h"
#include <debug.h>
#include <limits.h>
#define BLOCK_SIZE 16
#define NONCE_SIZE 12
@ -55,21 +55,41 @@ struct private_gcm_aead_t {
char h[BLOCK_SIZE];
};
/**
* architecture specific macros to convert a "long" to network order
*/
#if ULONG_MAX == 4294967295UL
#define htobelong htobe32
#define belongtoh htobe32
#elif ULONG_MAX == 18446744073709551615UL
#define htobelong htobe64
#define belongtoh htobe64
#endif
/**
* Bitshift a block right by one bit
*/
static void sr_block(u_char *block)
static void sr_block(char *block)
{
u_long *word = (u_long*)block;
int i;
for (i = BLOCK_SIZE - 1; i >= 0; i--)
for (i = 0; i < BLOCK_SIZE / sizeof(*word); i++)
{
block[i] = block[i] >> 1;
word[i] = htobelong(word[i]);
}
for (i = BLOCK_SIZE / sizeof(*word) - 1; i >= 0; i--)
{
word[i] >>= 1;
if (i != 0)
{
block[i] |= block[i - 1] << 7;
word[i] |= word[i - 1] << (sizeof(*word) * 8 - 1);
}
}
for (i = 0; i < BLOCK_SIZE / sizeof(*word); i++)
{
word[i] = belongtoh(word[i]);
}
}
/**