diff --git a/src/crypto/key_validator/key_validator_impl.cpp b/src/crypto/key_validator/key_validator_impl.cpp
index 429057f6c..55fd36f83 100644
--- a/src/crypto/key_validator/key_validator_impl.cpp
+++ b/src/crypto/key_validator/key_validator_impl.cpp
@@ -170,15 +170,57 @@ namespace libp2p::crypto::validator {
 
   outcome::result<void> KeyValidatorImpl::validateEcdsa(
       const PrivateKey &key) const {
-    // TODO(xDimon): Check if it possible to validate ECDSA key by some way.
-    //  issue: https://github.com/libp2p/cpp-libp2p/issues/103
+    // Basic ECDSA private key validation
+    // ECDSA private keys are typically 32 bytes for P-256, 48 bytes for P-384, 66 bytes for P-521
+    if (key.data.empty()) {
+      return KeyValidatorError::INVALID_PRIVATE_KEY;
+    }
+    
+    // Check for reasonable key sizes (32-66 bytes covers most common curves)
+    if (key.data.size() < 32 || key.data.size() > 66) {
+      return KeyValidatorError::WRONG_PRIVATE_KEY_SIZE;
+    }
+    
+    // Check that the key is not all zeros (invalid private key)
+    bool all_zeros = true;
+    for (const auto& byte : key.data) {
+      if (byte != 0) {
+        all_zeros = false;
+        break;
+      }
+    }
+    if (all_zeros) {
+      return KeyValidatorError::INVALID_PRIVATE_KEY;
+    }
+    
     return outcome::success();
   }
 
   outcome::result<void> KeyValidatorImpl::validateEcdsa(
       const PublicKey &key) const {
-    // TODO(xDimon): Check if it possible to validate ECDSA key by some way.
-    //  issue: https://github.com/libp2p/cpp-libp2p/issues/103
+    // Basic ECDSA public key validation
+    if (key.data.empty()) {
+      return KeyValidatorError::INVALID_PUBLIC_KEY;
+    }
+    
+    // ECDSA public keys are typically 64 bytes (uncompressed) or 33/49/67 bytes (compressed)
+    // for P-256/P-384/P-521 respectively
+    if (key.data.size() < 33 || key.data.size() > 133) {
+      return KeyValidatorError::WRONG_PUBLIC_KEY_SIZE;
+    }
+    
+    // Check that the key is not all zeros (invalid public key)
+    bool all_zeros = true;
+    for (const auto& byte : key.data) {
+      if (byte != 0) {
+        all_zeros = false;
+        break;
+      }
+    }
+    if (all_zeros) {
+      return KeyValidatorError::INVALID_PUBLIC_KEY;
+    }
+    
     return outcome::success();
   }
 
diff --git a/src/storage/sqlite.cpp b/src/storage/sqlite.cpp
index 33f47cedf..49245d5e1 100644
--- a/src/storage/sqlite.cpp
+++ b/src/storage/sqlite.cpp
@@ -22,12 +22,12 @@ namespace libp2p::storage {
     }
   }
 
-  int SQLite::getErrorCode() {
+  int SQLite::getErrorCode() const {
     return sqlite3_extended_errcode(db_.connection().get());
   }
 
-  std::string SQLite::getErrorMessage() {
-    int ec{getErrorCode()};
+  std::string SQLite::getErrorMessage() const {
+    const int ec{getErrorCode()};
     return (0 == ec) ? std::string()
                      : std::string(sqlite3_errstr(ec)) + ": "
                            + sqlite3_errmsg(db_.connection().get());