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-rw-r--r--ctr.c85
1 files changed, 69 insertions, 16 deletions
diff --git a/ctr.c b/ctr.c
index d94136c1..d217013c 100644
--- a/ctr.c
+++ b/ctr.c
@@ -36,40 +36,93 @@
#include "macros.h"
#include "memxor.h"
#include "nettle-internal.h"
-
+
+#define NBLOCKS 4
+
void
ctr_crypt(void *ctx, nettle_crypt_func f,
unsigned block_size, uint8_t *ctr,
unsigned length, uint8_t *dst,
const uint8_t *src)
{
- TMP_DECL(buffer, uint8_t, NETTLE_MAX_CIPHER_BLOCK_SIZE);
- TMP_ALLOC(buffer, block_size);
-
if (src != dst)
{
- for (; length >= block_size; length -= block_size, src += block_size, dst += block_size)
+ if (length == block_size)
{
f(ctx, block_size, dst, ctr);
- memxor(dst, src, block_size);
INCREMENT(block_size, ctr);
+ memxor(dst, src, block_size);
+ }
+ else
+ {
+ unsigned left;
+ uint8_t *p;
+
+ for (p = dst, left = length;
+ left >= block_size;
+ left -= block_size, p += block_size)
+ {
+ memcpy (p, ctr, block_size);
+ INCREMENT(block_size, ctr);
+ }
+
+ f(ctx, length - left, dst, dst);
+ memxor(dst, src, length - left);
+
+ if (left)
+ {
+ TMP_DECL(buffer, uint8_t, NETTLE_MAX_CIPHER_BLOCK_SIZE);
+ TMP_ALLOC(buffer, block_size);
+
+ f(ctx, block_size, buffer, ctr);
+ INCREMENT(block_size, ctr);
+ memxor3(dst + length - left, src + length - left, buffer, left);
+ }
}
}
else
{
- for (; length >= block_size; length -= block_size, src += block_size, dst += block_size)
+ if (length <= block_size)
{
+ TMP_DECL(buffer, uint8_t, NETTLE_MAX_CIPHER_BLOCK_SIZE);
+ TMP_ALLOC(buffer, block_size);
+
f(ctx, block_size, buffer, ctr);
- memxor3(dst, src, buffer, block_size);
INCREMENT(block_size, ctr);
- }
- }
- if (length > 0)
- {
- /* A final partial block */
+ memxor3(dst, src, buffer, length);
+ }
+ else
+ {
+ TMP_DECL(buffer, uint8_t, NBLOCKS * NETTLE_MAX_CIPHER_BLOCK_SIZE);
+ unsigned chunk = NBLOCKS * block_size;
+
+ TMP_ALLOC(buffer, chunk);
- f(ctx, block_size, buffer, ctr);
- memxor3(dst, src, buffer, length);
- INCREMENT(block_size, ctr);
+ for (; length >= chunk;
+ length -= chunk, src += chunk, dst += chunk)
+ {
+ unsigned n;
+ uint8_t *p;
+ for (n = 0, p = buffer; n < NBLOCKS; n++, p += block_size)
+ {
+ memcpy (p, ctr, block_size);
+ INCREMENT(block_size, ctr);
+ }
+ f(ctx, chunk, buffer, buffer);
+ memxor(dst, buffer, chunk);
+ }
+
+ if (length > 0)
+ {
+ /* Final, possibly partial, blocks */
+ for (chunk = 0; chunk < length; chunk += block_size)
+ {
+ memcpy (buffer + chunk, ctr, block_size);
+ INCREMENT(block_size, ctr);
+ }
+ f(ctx, chunk, buffer, buffer);
+ memxor3(dst, src, buffer, length);
+ }
+ }
}
}