diff --git a/docs/functions/core/flags/getters/why2_get_key_length.md b/docs/functions/core/flags/getters/why2_get_key_length.md
new file mode 100644
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+++ b/docs/functions/core/flags/getters/why2_get_key_length.md
@@ -0,0 +1,35 @@
+<!--
+This is part of WHY2
+Copyright (C) 2022 Václav Šmejkal
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+-->
+
+# why2_get_key_length
+
+## Parameters
+
+*This functions doesn't take any parameters.*
+
+## Attributes
+
+|                     |                                                |
+| ------------------  | ---------------------------------------------- |
+| **Return type**     | `unsigned long`                                |
+| **Header comment**  | *This functions doesn't have any description.* |
+| **Added in commit** | [`e85a14b2530d6c8a39be946f691a0f9047d38f73`](https://github.com/ENGO150/WHY2/commit/e85a14b2530d6c8a39be946f691a0f9047d38f73) |
+
+## Description
+
+Returns `key_length`, which is used in `key` generation. Also works as minimal length of `key` passed in [`why2_encrypt_text`](../../../encrypter/why2_encrypt_text).
\ No newline at end of file
diff --git a/docs/functions/index.md b/docs/functions/index.md
index bd1a057..6dc1e5e 100644
--- a/docs/functions/index.md
+++ b/docs/functions/index.md
@@ -50,6 +50,7 @@ You can find documentation for every *public* function of WHY2 below.
 | Function                                                                      | Description                             |
 | ----------------------------------------------------------------------------- | --------------------------------------- |
 | [`why2_get_encryption_separator`](./core/flags/getters/why2_get_encryption_separator) | *This functions doesn't have any description.* |
+| [`why2_get_key_length`](./core/flags/getters/why2_get_key_length) | *This functions doesn't have any description.*      |
 
 ## Logger