1. From Setup, in the Quick Find box, enter Matching Rules, and then select Matching Rules.
2. Deactivate the matching rule that reference fields you want to encrypt. If your matching rule is associated with an active duplicate rule, first deactivate the duplicate rule from the Duplicate Rules page. Then return to the Matching Rules page and deactivate the matching rule.
3. From Setup, in the Quick Find box, enter Platform Encryption, and then select Encryption Policy.
4. Click Encrypt Fields.
5. Click Edit.
6. Select the fields you want to encrypt, and select Deterministic from the Encryption Scheme list.
7. Click Save.
8. After you get the email verifying encryption’s been enabled on your fields, reactivate your matching rule and associated duplicate management rule.Matching rules used in duplicate management now return exact and fuzzy matches on encrypted data.