Crypto::Secret Add #copy_from, #move_from

Fix Sodium typo

README.md

@@ -77,6 +77,9 @@ slice = method_that_return_bytes()
 secret = Crypto::Secret::Bidet.move_from slice # erases slice
 # or
 secret = Crypto::Secret::Bidet.copy_from slice
+# or
+secret = Crypto::Secret::Bidet size_in_bytes
+secret.move_from slice
 ```
 
 ## What is a Secret?

src/crypto-secret/class_methods.cr

@@ -13,9 +13,7 @@ module Crypto::Secret::ClassMethods
   # Returns a **readonly** Secret
   def copy_from(data : Bytes)
     new(data.bytesize).tap do |obj|
-      obj.readwrite do |slice|
-        data.copy_to slice
-      end
+      obj.copy_from data
     end
   end
 

src/crypto-secret/key.cr

@@ -6,7 +6,7 @@ require "./bidet"
 #
 # Uses `Sodium::SecureBuffer` If "sodium" is required before "crypto-secret"
 {% if @type.has_constant?("Sodium") %}
-  class Crypto::Secret::Key < ::Sodum::SecureBuffer
+  class Crypto::Secret::Key < ::Sodium::SecureBuffer
   end
 {% else %}
   # TODO: mlock

src/crypto-secret/secret.cr

@@ -38,11 +38,29 @@ module Crypto::Secret
   extend ClassMethods
 
   # For debugging.
+  #
   # Returned String **not** tracked or wiped
   def hexstring : String
     readonly &.hexstring
   end
 
+  # Copies then wipes *data*
+  #
+  # Prefer this method over `#copy_from`
+  def move_from(data : Bytes) : Nil
+    copy_from data
+  ensure
+    data.wipe
+  end
+
+  # Copies from *data*
+  def copy_from(data : Bytes) : Nil
+    readwrite do |slice|
+      slice.copy_from data
+    end
+  end
+
+  # Fills `Secret` with secure random data
   def random : self
     readwrite do |slice|
       Random::Secure.random_bytes slice