Add isZeroKey() procedures.

eth_keys/libsecp256k1.nim

@@ -318,3 +318,17 @@ proc signRawMessage*(data: openarray[byte], seckey: PrivateKey,
                                       nil, nil) != 1:
     return(EthKeysStatus.Error)
   return(EthKeysStatus.Success)
+
+proc isZeroKey*(seckey: PrivateKey): bool =
+  ## Check if private key `seckey` contains only 0 bytes.
+  result = true
+  for i in seckey.data:
+    if i != byte(0):
+      result = false
+
+proc isZeroKey*(pubkey: PublicKey): bool =
+  ## Check if public key `pubkey` contains only 0 bytes.
+  result = true
+  for i in pubkey.data:
+    if i != byte(0):
+      result = false

tests/tests.nim

@@ -253,3 +253,15 @@ suite "ECC/ECDSA/ECDHE tests suite":
         ecdhAgree(aliceSecret, bobPublic, secret1) == Success
         ecdhAgree(bobSecret, alicePublic, secret2) == Success
         secret1 == secret2
+
+  test "isZeroKey() checks":
+    var seckey1: PrivateKey
+    var pubkey1: PublicKey
+    var seckey2 = newPrivateKey()
+    var pubkey2 = seckey2.getPublicKey()
+
+    check:
+      seckey1.isZeroKey() == true
+      pubkey1.isZeroKey() == true
+      seckey2.isZeroKey() == false
+      pubkey2.isZeroKey() == false