diff --git a/README.md b/README.md
index 713dddb..f03c3d0 100644
--- a/README.md
+++ b/README.md
@@ -83,8 +83,8 @@ Several features in libsodium are already provided by Crystal:
 | [`Sodium::Cipher::SecretStream`](https://didactic-drunk.github.io/sodium.cr/Sodium/Cipher/SecretStream/XChaCha20Poly1305.html) | I have a shared key and want encrypt + authenticate streamed data. |
 | [`Sodium::Digest::Blake2b`](https://didactic-drunk.github.io/sodium.cr/Sodium/Digest::Blake2b.html) | I want to hash data fast and securely. |
 | `Sodium::Digest::SipHash` | I want to hash data really fast and less securely. (Not implemented yet) |
-| [`Sodium::Pwhash`](https://didactic-drunk.github.io/sodium.cr/Sodium/Pwhash.html) | I want to hash a password and store it. |
-| [`Sodium::Pwhash`](https://didactic-drunk.github.io/sodium.cr/Sodium/Pwhash.html) | I want to derive a key from a password. |
+| [`Sodium::Password::Hash`](https://didactic-drunk.github.io/sodium.cr/Sodium/Password/Hash.html) | I want to hash a password and store it. |
+| [`Sodium::Password::Key`](https://didactic-drunk.github.io/sodium.cr/Sodium/Password/Key.html) | I want to derive a key from a password. |
 | [`Sodium::Kdf`](https://didactic-drunk.github.io/sodium.cr/Sodium/Kdf.html) | I have a high quality master key and want to make subkeys. |
 | [`Sodium::Cipher::Chalsa`](https://didactic-drunk.github.io/sodium.cr/Sodium/Cipher/Chalsa.html) | What goes with guacamole? |
 | Everything else | I want to design my own crypto protocol and probably do it wrong. |
@@ -228,15 +228,31 @@ subkey3 = kdf.derive "context2", 0, 32
 subkey4 = kdf.derive "context2", 1, 64
 ```
 
-### Password Hashing
+### Password based keys
 ```crystal
-pwhash = Sodium::Pwhash.new
+pwcreate = Sodium::Password::Key::Create.new
 
-pwhash.memlimit = Sodium::Pwhash::MEMLIMIT_MIN
-pwhash.opslimit = Sodium::Pwhash::OPSLIMIT_MIN
+# Take approximately 1 second to derive a key.
+pwcreate.tcost = 1.0
 
 pass = "1234"
-hash = pwhash.hash_str pass
+key, params = pwcreate.create_key pass
+# Store `params` or `params.to_h` for later.
+
+# Derive the same key from the stored params.
+pwkey = Sodium::Password::Key.from_params params.to_h
+key = pekey.derive_key pass
+```
+
+### Password Hashing
+```crystal
+pwhash = Sodium::Password::Hash.new
+
+pwhash.mem = Sodium::Password::MEMLIMIT_MIN
+pwhash.ops = Sodium::Password::OPSLIMIT_MIN
+
+pass = "1234"
+hash = pwhash.create pass
 pwhash.verify hash, pass
 ```
 
@@ -260,6 +276,8 @@ Ops limit →
 | 2097152K |  2.119s |
 |   Memory |
 
+
+
 ## Contributing
 
 1. Fork it ( https://github.com/didactic-drunk/sodium.cr/fork )
diff --git a/examples/constants.cr b/examples/constants.cr
index 9c4e0b4..9c05ae3 100644
--- a/examples/constants.cr
+++ b/examples/constants.cr
@@ -23,17 +23,17 @@ puts ""
 puts ""
 
 {% for name in %w(OPSLIMIT_MIN OPSLIMIT_INTERACTIVE OPSLIMIT_MODERATE OPSLIMIT_SENSITIVE OPSLIMIT_MAX) %}
-  puts "Sodium::Password::{{ name.id }} #{Sodium::Pwhash::{{ name.id }}}"
+  puts "Sodium::Password::{{ name.id }} #{Sodium::Password::{{ name.id }}}"
 {% end %}
 puts ""
 
 {% for name in %w(MEMLIMIT_MIN MEMLIMIT_INTERACTIVE MEMLIMIT_MAX) %}
-  puts "Sodium::Password::{{ name.id }} #{Sodium::Pwhash::{{ name.id }}}"
+  puts "Sodium::Password::{{ name.id }} #{Sodium::Password::{{ name.id }}}"
 {% end %}
 puts ""
 
 {% for name in %w(SALT_SIZE STR_SIZE) %}
-  puts "Sodium::Password::{{ name.id }} #{Sodium::Pwhash::{{ name.id }}}"
+  puts "Sodium::Password::{{ name.id }} #{Sodium::Password::{{ name.id }}}"
 {% end %}
 puts ""
 
diff --git a/src/sodium/password.cr b/src/sodium/password.cr
index 242e9b8..e9db0c9 100644
--- a/src/sodium/password.cr
+++ b/src/sodium/password.cr
@@ -2,13 +2,15 @@ require "./lib_sodium"
 require "./secure_buffer"
 
 # [Argon2 Password Hashing](https://libsodium.gitbook.io/doc/password_hashing/the_argon2i_function)
-# * #store #verify #needs_rehash? are used together for password verification.
-# * #derive_key is used on it's own to generate password based keys.
+# * `Sodium::Password::Hash`
+# * - Use for server side authentication replacing scrypt, bcrypt or crypt.
+# * `Sodium::Password::Key::Create`
+# * - Use to create a key with auto set parameters based on time.
+# * - Often used in single user application such as password safes, gpg/ssh keys or other encrypted storage.
+# * `Sodium::Password::Key`
+# * - Use with the `params` returned by `Create#create_key` or set your own to derive a consistent key or kdf.
 #
 # **See `examples/pwhash_selector.cr` for help on selecting parameters.**
-#
-# ## Creating a key for encryption with auto set parameters based on time.
-#
 module Sodium::Password
   OPSLIMIT_MIN         = LibSodium.crypto_pwhash_opslimit_min
   OPSLIMIT_INTERACTIVE = LibSodium.crypto_pwhash_opslimit_interactive
diff --git a/src/sodium/password/abstract.cr b/src/sodium/password/abstract.cr
index 15aa3a6..fc67181 100644
--- a/src/sodium/password/abstract.cr
+++ b/src/sodium/password/abstract.cr
@@ -1,5 +1,4 @@
-require "../lib_sodium"
-require "../secure_buffer"
+require "../password"
 
 abstract class Sodium::Password::Abstract
   property ops = OPSLIMIT_INTERACTIVE
@@ -29,8 +28,8 @@ abstract class Sodium::Password::Abstract
     if pw.responds_to?(:tcost=) && (tcost = hash["tcost"]?)
       pw.tcost = tcost.as(Float64)
     end
-    if pw.responds_to?(:auth=) && (auth = hash["auth"]?)
-      pw.auth = auth.as(Bytes)
+    if pw.responds_to?(:verify=) && (verify = hash["verify"]?)
+      pw.verify = verify.as(Bytes)
     end
 
     pw
diff --git a/src/sodium/password/create_key.cr b/src/sodium/password/create_key.cr
index 7df8e9e..b25c832 100644
--- a/src/sodium/password/create_key.cr
+++ b/src/sodium/password/create_key.cr
@@ -20,12 +20,15 @@ require "./key"
 # key, params = pwkc.create_key pass, 32
 #
 # # Save params.[mode, ops, mem, salt, key_size] to derive the same key later.
+# # Or serialize `params.to_h`
 # ```
 #
 # ## Deriving a previously created key.
 #
 # Usage:
 # ```
+# pwkey = Sodium::Password::Key.from_params hash
+# # Or
 # pwkey = Sodium::Password::Key.new
 # pwkey.mode = Mode.parse serialized[:mode]
 # pwkey.ops = serialized[:ops]
diff --git a/src/sodium/password/hash.cr b/src/sodium/password/hash.cr
index 80b594f..73121f7 100644
--- a/src/sodium/password/hash.cr
+++ b/src/sodium/password/hash.cr
@@ -1,6 +1,23 @@
 require "./abstract"
 
 module Sodium::Password
+  # Argon2 password hashing.  A modern substitute for scrypt, bcrypt or crypt.
+  #
+  # Often used to store password hashes on a server and authenticate clients against the stored hash.
+  #
+  # Usage:
+  # ```crystal
+  # pwhash = Sodium::Password::Hash.new
+  #
+  # pwhash.mem = Sodium::Password::MEMLIMIT_MIN
+  # pwhash.ops = Sodium::Password::OPSLIMIT_MIN
+  #
+  # pass = "1234"
+  # hash = pwhash.create pass
+  # pwhash.verify hash, pass
+  # ```
+  #
+  # Use `examples/pwhash_selector.cr` to help choose ops/mem limits.
   class Hash < Abstract
     # Apply the most recent password hashing algorithm against a password.
     # Returns a opaque String which includes:
diff --git a/src/sodium/password/params.cr b/src/sodium/password/params.cr
index 4c394c0..a16f3cf 100644
--- a/src/sodium/password/params.cr
+++ b/src/sodium/password/params.cr
@@ -1,14 +1,18 @@
 # Contains the params necessary for #derive_key.
 class Sodium::Password::Params
-  property mode : Mode
   property ops : UInt64
   property mem : UInt64
+  property mode : Mode?
   property salt : Bytes?
   property key_size : Int32?
-  property tcost : Float64?
-  property auth : Bytes?
 
-  def initialize(@mode, @ops, @mem, @salt = nil, @key_size = nil, @tcost = nil, @auth = nil)
+  # Information only.  Not used to derive a key.
+  property tcost : Float64?
+
+  # Application specific param to verify a password.
+  property verify : Bytes?
+
+  def initialize(@mode, @ops, @mem, @salt = nil, @key_size = nil, @tcost = nil, @verify = nil)
   end
 
   def to_h
@@ -27,14 +31,10 @@ class Sodium::Password::Params
     if ks = @key_size
       hash["key_size"] = ks
     end
-    if au = @auth
-      hash["auth"] = au
+    if v = @verify
+      hash["verify"] = v
     end
 
     hash
   end
-
-  def self.from_h(hash)
-    self.new Pwhash::Mode.parse(hash["mode"]), hash["ops"], hash["mem"], hash["tcost"]?, hash["salt"]?
-  end
 end