Hi Raymond,
Le 09/12/2024 à 17:06, Raymond Mao a écrit :
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Hi Philippe,
On Mon, 9 Dec 2024 at 04:42, Philippe Reynes
<philippe.rey...@softathome.com> wrote:
Adds the support of the hmac based on sha256.
This implementation is based on rfc2104.
Signed-off-by: Philippe Reynes <philippe.rey...@softathome.com>
---
include/u-boot/sha256.h | 4 ++++
lib/mbedtls/sha256.c | 38 ++++++++++++++++++++++++++++++++++++++
lib/sha256.c | 37 +++++++++++++++++++++++++++++++++++++
3 files changed, 79 insertions(+)
diff --git a/include/u-boot/sha256.h b/include/u-boot/sha256.h
index 44a9b528b48..2f12275b703 100644
--- a/include/u-boot/sha256.h
+++ b/include/u-boot/sha256.h
@@ -45,4 +45,8 @@ void sha256_finish(sha256_context * ctx, uint8_t
digest[SHA256_SUM_LEN]);
void sha256_csum_wd(const unsigned char *input, unsigned int ilen,
unsigned char *output, unsigned int chunk_sz);
+void sha256_hmac(const unsigned char *key, int keylen,
+ const unsigned char *input, unsigned int ilen,
+ unsigned char *output);
+
#endif /* _SHA256_H */
diff --git a/lib/mbedtls/sha256.c b/lib/mbedtls/sha256.c
index 24aa58fa674..1b9fc1a8503 100644
--- a/lib/mbedtls/sha256.c
+++ b/lib/mbedtls/sha256.c
@@ -8,6 +8,7 @@
#ifndef USE_HOSTCC
#include <cyclic.h>
#endif /* USE_HOSTCC */
+#include <string.h>
#include <u-boot/sha256.h>
const u8 sha256_der_prefix[SHA256_DER_LEN] = {
@@ -60,3 +61,40 @@ void sha256_csum_wd(const unsigned char *input,
unsigned int ilen,
sha256_finish(&ctx, output);
}
+
+void sha256_hmac(const unsigned char *key, int keylen,
+ const unsigned char *input, unsigned int ilen,
+ unsigned char *output)
+{
+ int i;
+ sha256_context ctx;
+ unsigned char k_ipad[64];
+ unsigned char k_opad[64];
+ unsigned char tmpbuf[32];
+
+ memset(k_ipad, 0x36, 64);
+ memset(k_opad, 0x5C, 64);
+
+ for (i = 0; i < keylen; i++) {
+ if (i >= 64)
+ break;
+
+ k_ipad[i] ^= key[i];
+ k_opad[i] ^= key[i];
+ }
+
You are assuming that the key length is at most 64 bytes.
But according to the HMAC specification:
If the key is longer than the hash block size (64 bytes for SHA256),
it should be hashed first to produce a shorter key.
If the key is shorter than 64 bytes, it should be zero-padded to 64 bytes.
good catch, you're right, I've missed this part.
I fix it in v4, and I also have added more test unit.
btw: the sha1_hmac has the same issue.
+ sha256_starts(&ctx);
+ sha256_update(&ctx, k_ipad, sizeof(k_ipad));
+ sha256_update(&ctx, input, ilen);
+ sha256_finish(&ctx, tmpbuf);
+
+ sha256_starts(&ctx);
+ sha256_update(&ctx, k_opad, sizeof(k_opad));
+ sha256_update(&ctx, tmpbuf, sizeof(tmpbuf));
+ sha256_finish(&ctx, output);
+
+ memset(k_ipad, 0, sizeof(k_ipad));
+ memset(k_opad, 0, sizeof(k_opad));
+ memset(tmpbuf, 0, sizeof(tmpbuf));
+ memset(&ctx, 0, sizeof(sha256_context));
+}
diff --git a/lib/sha256.c b/lib/sha256.c
index fb195d988f1..66224c92dd9 100644
--- a/lib/sha256.c
+++ b/lib/sha256.c
@@ -300,3 +300,40 @@ void sha256_csum_wd(const unsigned char
*input, unsigned int ilen,
sha256_finish(&ctx, output);
}
+
+void sha256_hmac(const unsigned char *key, int keylen,
+ const unsigned char *input, unsigned int ilen,
+ unsigned char *output)
+{
+ int i;
+ sha256_context ctx;
+ unsigned char k_ipad[64];
+ unsigned char k_opad[64];
+ unsigned char tmpbuf[32];
+
+ memset(k_ipad, 0x36, 64);
+ memset(k_opad, 0x5C, 64);
+
+ for (i = 0; i < keylen; i++) {
+ if (i >= 64)
+ break;
+
+ k_ipad[i] ^= key[i];
+ k_opad[i] ^= key[i];
+ }
+
+ sha256_starts(&ctx);
+ sha256_update(&ctx, k_ipad, sizeof(k_ipad));
+ sha256_update(&ctx, input, ilen);
+ sha256_finish(&ctx, tmpbuf);
+
+ sha256_starts(&ctx);
+ sha256_update(&ctx, k_opad, sizeof(k_opad));
+ sha256_update(&ctx, tmpbuf, sizeof(tmpbuf));
+ sha256_finish(&ctx, output);
+
+ memset(k_ipad, 0, sizeof(k_ipad));
+ memset(k_opad, 0, sizeof(k_opad));
+ memset(tmpbuf, 0, sizeof(tmpbuf));
+ memset(&ctx, 0, sizeof(sha256_context));
+}
I understand now we have duplicated 'shaX_csum_wd()' under lib and
lib/mbedtls.
That is because at the time when MbedTLS was added in, _csum_wd() is
the only
duplicated function and it is a trade-off comparing with creating a
new common
file for each algorithm.
But it is not the case if the number of these duplicated functions is
increasing.
Do you mind moving them into a common file with the one you created?
At least for sha256 with this patch I think.
In the v4, I have moved the function sha256_csum_wd() to the file
sha256_common.c
I plan to do another serie for sha1 and sha512.
Regards,
Raymond
--
2.25.1
Regards,
Philippe
