README.md in blind_index-0.3.0 vs README.md in blind_index-0.3.2

@@ -40,11 +40,11 @@
   attr_encrypted :email, key: [ENV["EMAIL_ENCRYPTION_KEY"]].pack("H*")
   blind_index :email, key: [ENV["EMAIL_BLIND_INDEX_KEY"]].pack("H*")
 end
 ```
 
-We use environment variables to store the keys ([dotenv](https://github.com/bkeepers/dotenv) is great for this). *Do not commit them to source control.* Generate one key for encryption and one key for hashing. You can generate keys in the Rails console with:
+We use environment variables to store the keys as hex-encoded strings ([dotenv](https://github.com/bkeepers/dotenv) is great for this). *Do not commit them to source control.* Generate one key for encryption and one key for hashing. You can generate keys in the Rails console with:
 
 ```ruby
 SecureRandom.hex(32)
 ```
 
@@ -141,35 +141,46 @@
 end
 ```
 
 The default is `10000`. Changing this value requires you to recompute the blind index.
 
-
 ### scrypt
 
-:warning: *Not production ready yet*
-
 Add [scrypt](https://github.com/pbhogan/scrypt) to your Gemfile and use:
 
 ```ruby
 class User < ApplicationRecord
   blind_index :email, algorithm: :scrypt, ...
 end
 ```
 
-### Argon2
+Set the cost parameters with:
 
-:warning: *Not production ready yet*
+```ruby
+class User < ApplicationRecord
+  blind_index :email, algorithm: :scrypt, cost: {n: 4096, r: 8, p: 1}, ...
+end
+```
 
+### Argon2
+
 Add [argon2](https://github.com/technion/ruby-argon2) to your Gemfile and use:
 
 ```ruby
 class User < ApplicationRecord
   blind_index :email, algorithm: :argon2, ...
 end
 ```
 
+Set the cost parameters with:
+
+```ruby
+class User < ApplicationRecord
+  blind_index :email, algorithm: :argon2, cost: {t: 3, m: 12}, ...
+end
+```
+
 ## Reference
 
 By default, blind indexes are encoded in Base64. Set a different encoding with:
 
 ```ruby
@@ -192,10 +203,18 @@
 
 ```ruby
 SecureRandom.hex(32)
 ```
 
-Set the new key and recompute the blind index.
+Update your model to convert the hex key to binary.
+
+```ruby
+class User < ApplicationRecord
+  blind_index :email, key: [ENV["EMAIL_BLIND_INDEX_KEY"]].pack("H*")
+end
+```
+
+And recompute the blind index.
 
 ```ruby
 User.find_each do |user|
   user.compute_email_bidx
   user.save!