# SDK3 compatibility mode for Key Storage Provider (KSP) for AWS CloudHSM
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Key Storage Provider (KSP) implements different approaches for HSM key interaction:
+ Client SDK 5: Provides direct communication with keys stored in the HSM, eliminating the need for local reference files
+ Client SDK 3: Maintains local files on the Windows server that act as references to keys stored in the HSM, using these files to facilitate key operations

For customers migrating from Client SDK 3 to Client SDK 5, enabling SDK3 compatibility mode option supports operations using existing key reference files while preserving the underlying HSM key storage architecture.

## Enable SDK3 compatibility mode
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#### [ Windows ]

**To enable SDK3 compatibility mode for Key Storage Provider (KSP) for Client SDK 5 in Windows**
+ You can use the following command to enable SDK3 compatibility mode:

  ```
  PS C:\> & "C:\Program Files\Amazon\CloudHSM\bin\configure-ksp.exe" --enable-sdk3-compatibility-mode
  ```

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## Disable SDK3 compatibility mode
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#### [ Windows ]

**To disable SDK3 compatibility mode for Key Storage Provider (KSP) for Client SDK 5 in Windows**
+ You can use the following command to disable SDK3 compatibility mode:

  ```
  PS C:\> & "C:\Program Files\Amazon\CloudHSM\bin\configure-ksp.exe" --disable-sdk3-compatibility-mode
  ```

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