minor #6595 Added a note about "encoding vs. hashing" passwords (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
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Added a note about "encoding vs. hashing" passwords

It's impossible to replace "encode" by "hash" in Symfony code/docs ... but we could add a short note about this to fix #5688.

Commits
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a5cb692 Added a note about "encoding vs. hashing" passwords

Author: wouterj

book/security.rst

@@ -1148,6 +1148,12 @@ is defined by the ``target`` parameter above (e.g. the ``homepage``).
 Dynamically Encoding a Password
 -------------------------------
 
+.. note::
+
+    For historical reasons, Symfony uses the term *"password encoding"* when it
+    should really refer to *"password hashing"*. The "encoders" are in fact
+    `cryptographic hash functions`_.
+
 If, for example, you're storing users in the database, you'll need to encode
 the users' passwords before inserting them. No matter what algorithm you
 configure for your user object, the hashed password can always be determined
@@ -1319,4 +1325,5 @@ Learn More from the Cookbook
 
 .. _`online tool`: https://www.dailycred.com/blog/12/bcrypt-calculator
 .. _`frameworkextrabundle documentation`: https://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/index.html
+.. _`cryptographic hash functions`: https://en.wikipedia.org/wiki/Cryptographic_hash_function
 .. _`HWIOAuthBundle`: https://github.com/hwi/HWIOAuthBundle