(nuttx) 02/07: crypto/ecc: supports exporting generated keys in uncompressed form

[xi...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/nuttx.git

commit be2e72dac22764e7617ecee00f237c6bd3ae50bc
Author: makejian <ma...@xiaomi.com>
AuthorDate: Thu Aug 7 15:21:12 2025 +0800

    crypto/ecc: supports exporting generated keys in uncompressed form
    
    Export public keys as separate X and Y coordinates for uncompressed format.
    
    Signed-off-by: makejian <ma...@xiaomi.com>
---
 crypto/ecc.c         | 42 ++++++++++++++++++++++++++++++++++++++++++
 include/crypto/ecc.h |  4 ++++
 2 files changed, 46 insertions(+)

diff --git a/crypto/ecc.c b/crypto/ecc.c
index 0a94621aa6f..f1a924b7d71 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -1541,6 +1541,48 @@ int ecc_make_key(uint8_t publickey[ECC_BYTES + 1],
   return 1;
 }
 
+int ecc_make_key_uncomp(uint8_t publickey_x[ECC_BYTES],
+                        uint8_t publickey_y[ECC_BYTES],
+                        uint8_t privatekey[ECC_BYTES])
+{
+  uint64_t l_private[NUM_ECC_DIGITS];
+  eccpoint_t l_public;
+  unsigned l_tries = 0;
+
+  do
+    {
+      if (l_tries++ >= MAX_TRIES)
+        {
+          return 0;
+        }
+
+      arc4random_buf(l_private, NUM_ECC_DIGITS);
+
+      if (vli_iszero(l_private))
+        {
+          continue;
+        }
+
+      /* Make sure the private key is in the range [1, n-1].
+       * For the supported curves, n is always large enough that we only
+       * need to subtract once at most.
+       */
+
+      if (vli_cmp(g_curve_n, l_private) != 1)
+        {
+          vli_sub(l_private, l_private, g_curve_n);
+        }
+
+      eccpoint_mult(&l_public, &g_curve_g, l_private, NULL);
+    }
+  while (eccpoint_iszero(&l_public));
+
+  ecc_native2bytes(privatekey, l_private);
+  ecc_native2bytes(publickey_x, l_public.x);
+  ecc_native2bytes(publickey_y, l_public.y);
+  return 1;
+}
+
 int ecdh_shared_secret(const uint8_t publickey[ECC_BYTES + 1],
                        const uint8_t privatekey[ECC_BYTES],
                        uint8_t secret[ECC_BYTES])
diff --git a/include/crypto/ecc.h b/include/crypto/ecc.h
index eb3898eaabd..3c130e4b9dc 100644
--- a/include/crypto/ecc.h
+++ b/include/crypto/ecc.h
@@ -76,6 +76,10 @@ extern "C"
 int ecc_make_key(uint8_t publickey[ECC_BYTES + 1],
                  uint8_t privatekey[ECC_BYTES]);
 
+int ecc_make_key_uncomp(uint8_t publickey_x[ECC_BYTES],
+                        uint8_t publickey_y[ECC_BYTES],
+                        uint8_t privatekey[ECC_BYTES]);
+
 /* ecdh_shared_secret() function.
  * Compute a shared secret given your secret key and someone else's
  * public key.