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Hi Philippe,
On Thu, 12 Dec 2024 at 08:37, 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/sha256_common.c | 48
+++++++++++++++++++++++++++++++++++++++++
2 files changed, 52 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/sha256_common.c b/lib/sha256_common.c
index 7041abd26d9..46262ea99a2 100644
--- a/lib/sha256_common.c
+++ b/lib/sha256_common.c
@@ -48,3 +48,51 @@ 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 keybuf[64];
+ unsigned char k_ipad[64];
+ unsigned char k_opad[64];
+ unsigned char tmpbuf[32];
+ int keybuf_len;
+
+ if (keylen > 64) {
+ sha256_starts(&ctx);
+ sha256_update(&ctx, key, keylen);
+ sha256_finish(&ctx, keybuf);
+
+ keybuf_len = 32;
+ } else {
+ memcpy(keybuf, key, keylen);
+ keybuf_len = keylen;
+ }
+
+ memset(k_ipad, 0x36, 64);
+ memset(k_opad, 0x5C, 64);
+
+ for (i = 0; i < keybuf_len; i++) {
+ k_ipad[i] ^= keybuf[i];
+ k_opad[i] ^= keybuf[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(keybuf, 0, sizeof(keybuf));
+ memset(&ctx, 0, sizeof(sha256_context));
+}
--
2.25.1
The sha256 hmac common implementation now sounds good.
Do you have a comparison of performance with the MbedTLS
high-level API
mbedtls_md_hmac()?
I am wondering if it is worth using this API specially when
MbedTLS is enabled,
since it significantly simplifies the implementation.
