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modes/ocb128.c: ocb_lookup_l to allow non-contiguous lookup

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and CRYPTO_ocb128_encrypt to handle in==out.

Reviewed-by: Matt Caswell <matt@openssl.org>
This commit is contained in:
Andy Polyakov 2015-11-30 13:26:21 +01:00
parent 338f5727c8
commit b9e3d7e0f6
1 changed files with 29 additions and 8 deletions
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37
crypto/modes/ocb128.c
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@ -153,20 +153,34 @@ static void ocb_block_xor(const unsigned char *in1,
*/
static OCB_BLOCK *ocb_lookup_l(OCB128_CONTEXT *ctx, size_t idx)
{
if (idx <= ctx->l_index) {
size_t l_index = ctx->l_index;
if (idx <= l_index) {
return ctx->l + idx;
}
/* We don't have it - so calculate it */
ctx->l_index++;
if (ctx->l_index == ctx->max_l_index) {
ctx->max_l_index *= 2;
if (idx >= ctx->max_l_index) {
/*
* Each additional entry allows to process almost double as
* much data, so that in linear world the table will need to
* be expanded with smaller and smaller increments. Originally
* it was doubling in size, which was a waste. Growing it
* linearly is not formally optimal, but is simpler to implement.
* We grow table by minimally required 4*n that would accommodate
* the index.
*/
ctx->max_l_index += (idx - ctx->max_l_index + 4) & ~3;
ctx->l =
OPENSSL_realloc(ctx->l, ctx->max_l_index * sizeof(OCB_BLOCK));
if (!ctx->l)
return NULL;
}
ocb_double(ctx->l + (idx - 1), ctx->l + idx);
while (l_index <= idx) {
ocb_double(ctx->l + l_index, ctx->l + l_index + 1);
l_index++;
}
ctx->l_index = l_index;
return ctx->l + idx;
}
@ -228,7 +242,7 @@ int CRYPTO_ocb128_init(OCB128_CONTEXT *ctx, void *keyenc, void *keydec,
{
memset(ctx, 0, sizeof(*ctx));
ctx->l_index = 0;
ctx->max_l_index = 1;
ctx->max_l_index = 5;
ctx->l = OPENSSL_malloc(ctx->max_l_index * 16);
if (ctx->l == NULL)
return 0;
@ -252,6 +266,13 @@ int CRYPTO_ocb128_init(OCB128_CONTEXT *ctx, void *keyenc, void *keydec,
/* L_0 = double(L_$) */
ocb_double(&ctx->l_dollar, ctx->l);
/* L_{i} = double(L_{i-1}) */
ocb_double(ctx->l, ctx->l+1);
ocb_double(ctx->l+1, ctx->l+2);
ocb_double(ctx->l+2, ctx->l+3);
ocb_double(ctx->l+3, ctx->l+4);
ctx->l_index = 4; /* enough to process up to 496 bytes */
return 1;
}
@ -424,13 +445,13 @@ int CRYPTO_ocb128_encrypt(OCB128_CONTEXT *ctx,
/* C_i = Offset_i xor ENCIPHER(K, P_i xor Offset_i) */
inblock = (OCB_BLOCK *)(in + ((i - ctx->blocks_processed - 1) * 16));
ocb_block16_xor(&ctx->offset, inblock, &tmp1);
/* Checksum_i = Checksum_{i-1} xor P_i */
ocb_block16_xor(&ctx->checksum, inblock, &ctx->checksum);
ocb_encrypt(ctx, &tmp1, &tmp2, ctx->keyenc);
outblock =
(OCB_BLOCK *)(out + ((i - ctx->blocks_processed - 1) * 16));
ocb_block16_xor(&ctx->offset, &tmp2, outblock);
/* Checksum_i = Checksum_{i-1} xor P_i */
ocb_block16_xor(&ctx->checksum, inblock, &ctx->checksum);
}
/*