# Digital signature
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On Windows, Amazon DCV starts only digitally signed extension executables. There is no digital signature verification on Linux and macOS. Digital signatures are verified using the `WinVerifyTrust` function with the `WINTRUST_ACTION_GENERIC_VERIFY_V2` parameter.

**Important**  
During the development, it is possible to disable the verification for testing purposes. It is advisable not to set the following registry key outside of a development environment.

Adding the following registry key will allow DCV to load unsigned extensions executables on the server:

`[HKEY_USERS\S-1-5-18\Software\GSettings\com\nicesoftware\dcv\extensions] load-policy=all `

![\[Registry Editor window showing dcv folder structure and load-policy setting.\]](http://docs.aws.amazon.com/dcv/latest/extsdkguide/images/digital-sign.jpg)


To start unsigned extensions on the client, use the following command line parameter:

`--extensions-load-policy="all"`