From: Daiki Ueno <du...@redhat.com>
The ChaCha20 based header protection algorithm in QUIC requires a way
to set the initial value of counter:
https://quicwg.org/base-drafts/draft-ietf-quic-tls.html#name-chacha20-based-header-prote
This will add a new function chacha_set_counter, which takes an
8-octet initial value of the block counter.
Signed-off-by: Daiki Ueno <du...@redhat.com>
---
chacha-set-nonce.c | 7 +++++++
chacha.h | 5 +++++
nettle.texinfo | 12 ++++++++++++
testsuite/chacha-test.c | 37 +++++++++++++++++++++++++++++++++++--
4 files changed, 59 insertions(+), 2 deletions(-)
diff --git a/chacha-set-nonce.c b/chacha-set-nonce.c
index 607f176b..2c34e498 100644
--- a/chacha-set-nonce.c
+++ b/chacha-set-nonce.c
@@ -68,3 +68,10 @@ chacha_set_nonce96(struct chacha_ctx *ctx, const uint8_t
*nonce)
ctx->state[14] = LE_READ_UINT32(nonce + 4);
ctx->state[15] = LE_READ_UINT32(nonce + 8);
}
+
+void
+chacha_set_counter(struct chacha_ctx *ctx, const uint8_t *counter)
+{
+ ctx->state[12] = LE_READ_UINT32(counter + 0);
+ ctx->state[13] = LE_READ_UINT32(counter + 4);
+}
diff --git a/chacha.h b/chacha.h
index 429a55b6..440fe968 100644
--- a/chacha.h
+++ b/chacha.h
@@ -46,6 +46,7 @@ extern "C" {
#define chacha_set_key nettle_chacha_set_key
#define chacha_set_nonce nettle_chacha_set_nonce
#define chacha_set_nonce96 nettle_chacha_set_nonce96
+#define chacha_set_counter nettle_chacha_set_counter
#define chacha_crypt nettle_chacha_crypt
/* Currently, only 256-bit keys are supported. */
@@ -53,6 +54,7 @@ extern "C" {
#define CHACHA_BLOCK_SIZE 64
#define CHACHA_NONCE_SIZE 8
#define CHACHA_NONCE96_SIZE 12
+#define CHACHA_COUNTER_SIZE 8
#define _CHACHA_STATE_LENGTH 16
@@ -81,6 +83,9 @@ chacha_set_nonce(struct chacha_ctx *ctx, const uint8_t
*nonce);
void
chacha_set_nonce96(struct chacha_ctx *ctx, const uint8_t *nonce);
+void
+chacha_set_counter(struct chacha_ctx *ctx, const uint8_t *counter);
+
void
chacha_crypt(struct chacha_ctx *ctx, size_t length,
uint8_t *dst, const uint8_t *src);
diff --git a/nettle.texinfo b/nettle.texinfo
index 19eb6d34..0b339f51 100644
--- a/nettle.texinfo
+++ b/nettle.texinfo
@@ -1669,6 +1669,10 @@ ChaCha block size, 64.
Size of the nonce, 8.
@end defvr
+@defvr Constant CHACHA_COUNTER_SIZE
+Size of the counter, 8.
+@end defvr
+
@deftypefun void chacha_set_key (struct chacha_ctx *@var{ctx}, const uint8_t
*@var{key})
Initialize the cipher. The same function is used for both encryption and
decryption. Before using the cipher,
@@ -1681,6 +1685,14 @@ octets. This function also initializes the block
counter, setting it to
zero.
@end deftypefun
+@deftypefun void chacha_set_counter (struct chacha_ctx *@var{ctx}, const
uint8_t *@var{counter})
+Sets the block counter. It is always of size @code{CHACHA_COUNTER_SIZE},
+8 octets. This is rarely needed since @code{chacha_set_nonce}
+initializes the block counter to zero. When it is still necessary, this
+function must be called after @code{chacha_set_nonce}.
+
+@end deftypefun
+
@deftypefun void chacha_crypt (struct chacha_ctx *@var{ctx}, size_t
@var{length}, uint8_t *@var{dst}, const uint8_t *@var{src})
Encrypts or decrypts the data of a message, using ChaCha. When a
message is encrypted using a sequence of calls to @code{chacha_crypt},
diff --git a/testsuite/chacha-test.c b/testsuite/chacha-test.c
index d6489e9c..6875d4bb 100644
--- a/testsuite/chacha-test.c
+++ b/testsuite/chacha-test.c
@@ -38,8 +38,9 @@
#include "chacha-internal.h"
static void
-test_chacha(const struct tstring *key, const struct tstring *nonce,
- const struct tstring *expected, unsigned rounds)
+_test_chacha(const struct tstring *key, const struct tstring *nonce,
+ const struct tstring *expected, unsigned rounds,
+ const struct tstring *counter)
{
struct chacha_ctx ctx;
@@ -69,6 +70,9 @@ test_chacha(const struct tstring *key, const struct tstring
*nonce,
else
die ("Bad nonce size %u.\n", (unsigned) nonce->length);
+ if (counter)
+ chacha_set_counter(&ctx, counter->data);
+
chacha_crypt (&ctx, length, data, data);
ASSERT (data[-1] == 17);
@@ -98,6 +102,8 @@ test_chacha(const struct tstring *key, const struct tstring
*nonce,
ASSERT (nonce->length == CHACHA_NONCE_SIZE);
chacha_set_nonce(&ctx, nonce->data);
+ if (counter)
+ chacha_set_counter(&ctx, counter->data);
_chacha_core (out, ctx.state, rounds);
if (!MEMEQ(CHACHA_BLOCK_SIZE, out, expected->data))
@@ -117,6 +123,21 @@ test_chacha(const struct tstring *key, const struct
tstring *nonce,
}
}
+static void
+test_chacha(const struct tstring *key, const struct tstring *nonce,
+ const struct tstring *expected, unsigned rounds)
+{
+ _test_chacha(key, nonce, expected, rounds, NULL);
+}
+
+static void
+test_chacha_with_counter(const struct tstring *key, const struct tstring
*nonce,
+ const struct tstring *expected, unsigned rounds,
+ const struct tstring *counter)
+{
+ _test_chacha(key, nonce, expected, rounds, counter);
+}
+
void
test_main(void)
{
@@ -644,4 +665,16 @@ test_main(void)
"d2826446079faa09 14c2d705d98b02a2"
"b5129cd1de164eb9 cbd083e8a2503c4e"),
20);
+
+ /* This is identical to the 96-bit nonce test, but it manually sets
+ the counter value */
+ test_chacha_with_counter(SHEX("0001020304050607 08090a0b0c0d0e0f"
+ "1011121314151617 18191a1b1c1d1e1f"),
+ SHEX("0000004a00000000"),
+ SHEX("10f1e7e4d13b5915 500fdd1fa32071c4"
+ "c7d1f4c733c06803 0422aa9ac3d46c4e"
+ "d2826446079faa09 14c2d705d98b02a2"
+ "b5129cd1de164eb9 cbd083e8a2503c4e"),
+ 20,
+ SHEX("0100000000000009"));
}
--
2.24.1
_______________________________________________
nettle-bugs mailing list
nettle-bugs@lists.lysator.liu.se
http://lists.lysator.liu.se/mailman/listinfo/nettle-bugs
