Decrypt Function

Description

Reverses the operation of the Encrypt function applied on a data buffer, returning the data to its unencrypted state.

Syntax

hasp_status_t HASP_CALLCONV hasp_decrypt(
            hasp_handle_t handle,
            void * buffer,
            hasp_size_t length
            )

Parameters

`handle`	Handle for the session
`buffer`	Pointer to the buffer to be decrypted
`length`	Size (in bytes) of the buffer to be decrypted. Minimum size: 16 bytes. Maximum size: 4 GB.

Return Values

HASP_IDENTITY_RATE_LIMIT_EXCEEDED

HASP_LOCAL_COMM_ERR

HASP_REMOTE_COMM_ERR

Usage Notes

Decrypts data using the encryption engine in the Sentinel protection key. The specific session handle controls which Sentinel protection key and which Feature ID decrypt the data buffer. The same Feature ID that was used to encrypt a data buffer must be used to decrypt it. The encryption key remains in the Sentinel protection key. If the decryption fails, the data buffer is not modified.

To encrypt data, use the Encrypt function.

NOTE To defeat a protection key emulator attempting to bypass software protection, you can check periodically that the protection key is available and that a session for the key exists. This should not be done using GetSessionInfo (this function does not detect a remote broken session). Instead, use one of the following functions: Encrypt, Decrypt, Read, Write. These functions will return HASP_BROKEN_SESSION if a session for the protection key does not exist.