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# ENC encryption deprecated

> Notice that the legacy $ENC encryption implementation has been deprecated and replaced with a server-specific custom encryption key in Platform 6.

## Deprecation notice

The legacy `$ENC` encryption implementation has been deprecated and replaced with an enhanced version that uses a custom encryption key for each platform server. While the `$ENC` string notation remains in place, the underlying encryption mechanism now depends on a server-specific custom encryption key rather than the previous global encryption key.

This change may introduce differences between environments and affect:

* Secrets encrypted in previous platform versions
* Cross-environment data migration (development and stage environments may use the same adapter service config, but encrypted passwords will differ due to encryption key differences)

## What should I do?

If you are upgrading to Platform 6.0 or newer, read [Migration of encrypted secrets](/maintain/upgrade#migration-of-encrypted-secrets) in the Platform 6 upgrade guide before upgrading. Strings currently encrypted using `$ENC` will not work out-of-the-box after an upgrade to Platform 6, so it is important to know how to migrate and define your encryption keys in the Platform 6 configuration prior to platform start.

## Related reading

* [Legacy password encryption](/itential-platform/6/auth/aaa/configure-local-aaa-authentication#encrypt-passwords#legacy-encryption)
* [Platform 6 upgrade guide](/maintain/upgrade)

> Notice that the legacy $ENC encryption implementation has been deprecated and replaced with a server-specific custom encryption key in Platform 6.