Update overview.md

Author: jinruishao

articles/ai-services/content-safety/overview.md

@@ -189,6 +189,17 @@ Content Safety features have query rate limits in requests-per-second (RPS) or r
 
 If you need a faster rate, please [contact us](mailto:[email protected]) to request it.
 
+### Encryption
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+Content Safety encryption protects your data at rest. It encrypts your data as it is written in our datacenters and automatically decrypts it when you access it.
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+By default, data in Content Safety is encrypted using Microsoft Managed Keys (MMK). However, Content Safety supports both Microsoft Managed Keys (MMK) and Customer Managed Keys (CMK) for encryption. When CMK is selected, users can choose CMK and have the ability to select either user-assigned managed identities (UMI) or system-assigned managed identities (SMI).
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+![image](https://github.com/user-attachments/assets/e3ae2e32-a974-4255-8bbd-01a1bc114702)
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+
 
 ## Contact us