diff --git a/Pilz.Cryptography/SecureString.cs b/Pilz.Cryptography/SecureString.cs
index 54654c5..56b3a65 100644
--- a/Pilz.Cryptography/SecureString.cs
+++ b/Pilz.Cryptography/SecureString.cs
@@ -11,20 +11,19 @@ namespace Pilz.Cryptography
     public class SecureString
     {
         public static ICrypter DefaultCrypter { get; set; }
-
-        [JsonIgnore]
         public ICrypter Crypter { get; set; }
-
-        [JsonProperty]
         public string EncryptedValue { get; set; }
-
-        [JsonIgnore]
         public string Value
         {
-            get => GetCrypter().Decrypt(EncryptedValue);
+            get => GetCrypter()?.Decrypt(EncryptedValue);
             set => EncryptedValue = GetCrypter().Encrypt(value);
         }
 
+        [JsonConstructor]
+        private SecureString(JsonConstructorAttribute dummyAttribute)
+        {
+        }
+
         public SecureString() :
             this(string.Empty, true)
         {
@@ -73,7 +72,7 @@ namespace Pilz.Cryptography
         public static implicit operator string(SecureString value) => value?.Value;
         public static implicit operator SecureString(string value) => new SecureString(value, false);
 
-        public static bool operator ==(SecureString left, SecureString right) => left.EncryptedValue == right.EncryptedValue;
-        public static bool operator !=(SecureString left, SecureString right) => left.EncryptedValue != right.EncryptedValue;
+        public static bool operator ==(SecureString left, SecureString right) => left?.EncryptedValue == right?.EncryptedValue;
+        public static bool operator !=(SecureString left, SecureString right) => left?.EncryptedValue != right?.EncryptedValue;
     }
 }
diff --git a/Pilz.Cryptography/SecureStringJsonConverter.cs b/Pilz.Cryptography/SecureStringJsonConverter.cs
index 8a1f1f0..3d4a2ab 100644
--- a/Pilz.Cryptography/SecureStringJsonConverter.cs
+++ b/Pilz.Cryptography/SecureStringJsonConverter.cs
@@ -22,12 +22,13 @@ namespace Pilz.Json.Converters
             var idString = serializer.Deserialize<string>(reader);
             SecureString  id;
 
-            if (existingValue is object)
+            if (existingValue is SecureString)
+            {
                 id = (SecureString)existingValue;
+                id.EncryptedValue = idString;
+            }
             else
-                id = new SecureString();
-
-            id.EncryptedValue = idString;
+                id = new SecureString(idString, true);
 
             return id;
         }
diff --git a/Pilz.Cryptography/SimpleStringCrypter.cs b/Pilz.Cryptography/SimpleStringCrypter.cs
index 90df652..97a2da9 100644
--- a/Pilz.Cryptography/SimpleStringCrypter.cs
+++ b/Pilz.Cryptography/SimpleStringCrypter.cs
@@ -35,10 +35,13 @@ namespace Pilz.Cryptography
             byte[] bytes = TextEncoding.GetBytes(key);
             byte[] array = sha1CryptoServiceProvider.ComputeHash(bytes);
 
-            var output = new byte[checked(length - 1 + 1)];
-            array.CopyTo(output, 0);
+            var output = new byte[length];
+            var lowerLength = Math.Min(array.Length, output.Length);
+            
+            for (int i = 0; i < lowerLength; i++)
+                output[i] = array[i];
 
-            return array;
+            return output;
         }
 
         private string EncryptData(string plaintext)
@@ -63,7 +66,7 @@ namespace Pilz.Cryptography
 
         public string Encrypt(string plainValue)
         {
-            return EncryptData(plainValue);
+            return EncryptData(plainValue ?? string.Empty);
         }
 
         public string Decrypt(string encryptedValue)