diff --git a/src/Account/Address.php b/src/Account/Address.php
index b1522a8..767c64b 100644
--- a/src/Account/Address.php
+++ b/src/Account/Address.php
@@ -38,7 +38,10 @@ static function fromPublicKey( PublicKey $publicKey, ChainId $chainId = null ):
         $address = new Address;
         $wk = new \deemru\WavesKit( ( isset( $chainId ) ? $chainId : WavesConfig::chainId() )->asString() );
         $wk->setPublicKey( $publicKey->bytes(), true );
-        $address->address = Base58String::fromBytes( $wk->getAddress( true ) );
+        $bytes = $wk->getAddress( true );
+        if( !is_string( $bytes ) || strlen( $bytes ) !== Address::BYTE_LENGTH )
+            throw new Exception( __FUNCTION__ . ' bad key', ExceptionCode::BAD_KEY );
+        $address->address = Base58String::fromBytes( $bytes );
         return $address;
     }
 
diff --git a/src/Account/PrivateKey.php b/src/Account/PrivateKey.php
index e4384ca..0d04005 100644
--- a/src/Account/PrivateKey.php
+++ b/src/Account/PrivateKey.php
@@ -2,7 +2,9 @@
 
 namespace Waves\Account;
 
+use Exception;
 use Waves\Common\Base58String;
+use Waves\Common\ExceptionCode;
 
 class PrivateKey
 {
@@ -16,7 +18,10 @@ private function __construct(){}
     static function fromSeed( string $seed, int $nonce = 0 ): PrivateKey
     {
         $privateKey = new PrivateKey;
-        $privateKey->key = Base58String::fromBytes( ( new \deemru\WavesKit )->getPrivateKey( true, $seed, pack( 'N', $nonce ) ) );
+        $bytes = ( new \deemru\WavesKit )->getPrivateKey( true, $seed, pack( 'N', $nonce ) );
+        if( !is_string( $bytes ) || strlen( $bytes ) !== PrivateKey::LENGTH )
+            throw new Exception( __FUNCTION__ . ' bad key', ExceptionCode::BAD_KEY );
+        $privateKey->key = Base58String::fromBytes( $bytes );
         return $privateKey;
     }
 
diff --git a/src/Account/PublicKey.php b/src/Account/PublicKey.php
index 4716754..ff8e95e 100644
--- a/src/Account/PublicKey.php
+++ b/src/Account/PublicKey.php
@@ -2,7 +2,9 @@
 
 namespace Waves\Account;
 
+use Exception;
 use Waves\Common\Base58String;
+use Waves\Common\ExceptionCode;
 use Waves\Model\ChainId;
 
 class PublicKey
@@ -34,7 +36,10 @@ static function fromPrivateKey( PrivateKey $key ): PublicKey
         $publicKey = new PublicKey;
         $wk = new \deemru\WavesKit;
         $wk->setPrivateKey( $key->bytes(), true );
-        $publicKey->key = Base58String::fromBytes( $wk->getPublicKey( true ) );
+        $bytes = $wk->getPublicKey( true );
+        if( !is_string( $bytes ) || strlen( $bytes ) !== PublicKey::BYTES_LENGTH )
+            throw new Exception( __FUNCTION__ . ' bad key', ExceptionCode::BAD_KEY );
+        $publicKey->key = Base58String::fromBytes( $bytes );
         return $publicKey;
     }
 
diff --git a/src/Common/ExceptionCode.php b/src/Common/ExceptionCode.php
index 4107b22..7f1a75c 100644
--- a/src/Common/ExceptionCode.php
+++ b/src/Common/ExceptionCode.php
@@ -23,4 +23,5 @@ class ExceptionCode
     const BAD_CHAINID =     ExceptionCode::BASE | 16;
     const TIMEOUT =         ExceptionCode::BASE | 17;
     const UNEXPECTED =      ExceptionCode::BASE | 18;
+    const BAD_KEY =         ExceptionCode::BASE | 19;
 }