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[ctrtool] Improved efficiency of aes-ctr operations.

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This commit is contained in:
jakcron
2016-06-14 20:35:05 +08:00
parent de5c4e1b2a
commit 01cd4cba7b
8 changed files with 96 additions and 44 deletions
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ctrtool/ctr.c
+29 -17
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@@ -4,6 +4,7 @@
#include <time.h>
#include "ctr.h"
#include "utils.h"
void ctr_set_iv( ctr_aes_context* ctx,
@@ -15,23 +16,30 @@ void ctr_set_iv( ctr_aes_context* ctx,
void ctr_add_counter( ctr_aes_context* ctx,
u32 block_num )
{
u32 i, j;
for (i = 0; i < block_num; i++) {
for (j = 0x10; j > 0; j--) {
// increment u8 by 1
ctx->ctr[j - 1]++;
u32 ctr[4];
ctr[3] = getbe32(&ctx->ctr[0]);
ctr[2] = getbe32(&ctx->ctr[4]);
ctr[1] = getbe32(&ctx->ctr[8]);
ctr[0] = getbe32(&ctx->ctr[12]);
// if it didn't overflow to 0, then we can exit now
if (ctx->ctr[j - 1])
break;
// if we reach here, the next u8 needs to be incremented
// Loop to beginning back if needed
if (j == 1)
j = 0x10;
for (u32 i = 0; i < 4; i++) {
u64 total = ctr[i] + block_num;
// if there wasn't a wrap around, add the two together and exit
if (total <= 0xffffffff) {
ctr[i] += block_num;
break;
}
// add the difference
ctr[i] = (u32)(total - 0x100000000);
// carry to next word
block_num = (u32)(total >> 32);
}
putbe32(ctx->ctr + 0x00, ctr[3]);
putbe32(ctx->ctr + 0x04, ctr[2]);
putbe32(ctx->ctr + 0x08, ctr[1]);
putbe32(ctx->ctr + 0x0C, ctr[0]);
}
void ctr_set_counter( ctr_aes_context* ctx,
@@ -41,11 +49,15 @@ void ctr_set_counter( ctr_aes_context* ctx,
}
void ctr_init_counter( ctr_aes_context* ctx,
u8 key[16],
u8 ctr[16] )
void ctr_init_key(ctr_aes_context* ctx,
u8 key[16])
{
aes_setkey_enc(&ctx->aes, key, 128);
}
void ctr_init_counter( ctr_aes_context* ctx,
u8 ctr[16] )
{
ctr_set_counter(ctx, ctr);
}