diff --git a/ocean_lib/ocean/crypto.py b/ocean_lib/ocean/crypto.py
index 8bf6f2e30..f45289c0b 100644
--- a/ocean_lib/ocean/crypto.py
+++ b/ocean_lib/ocean/crypto.py
@@ -18,8 +18,8 @@
 def calc_symkey(base_str: str) -> str:
     """Compute a symmetric private key that's a function of the base_str"""
     base_b = base_str.encode("utf-8")  # bytes
-    hash_b = sha256(base_b)
-    symkey_b = b64encode(str(hash_b).encode("ascii"))[:43] + b"="  # bytes
+    hash_b = sha256(base_b).hexdigest()
+    symkey_b = b64encode(hash_b.encode("ascii"))[:43] + b"="  # bytes
     symkey = symkey_b.decode("ascii")
     return symkey
 
diff --git a/ocean_lib/ocean/test/test_crypto.py b/ocean_lib/ocean/test/test_crypto.py
index cfc121041..a4b4533d7 100644
--- a/ocean_lib/ocean/test/test_crypto.py
+++ b/ocean_lib/ocean/test/test_crypto.py
@@ -12,6 +12,8 @@ def test_symkey():
     base_str = "foo"
     symkey = crypto.calc_symkey(base_str)
     assert isinstance(symkey, str)
+    wrong_symkey = crypto.calc_symkey("testwrong")
+    assert wrong_symkey != symkey, "NOK : wrong_sym_key is the same as sym_key"
 
 
 @enforce_types