Decrypt data BLOB

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4D v20.6

Decrypt data BLOB


Decrypt data BLOB ( blobToDecrypt ; keyObject \| passPhrase ; salt ; decryptedBLOB ) -> Function result

Parameter	Type	Description
blobToDecrypt	BLOB	BLOB to decrypt
keyObject \| passPhrase	Object, Text	JSON object containing the encryption key or passphrase for direct encryption key generation (text)
salt	Longint	Additional salt for algorithm
decryptedBLOB	BLOB	decrypted BLOB
Function result	Boolean	True if decryption has been correctly performed, False otherwise

Description

The Decrypt data BLOB command decrypts the blobToDecrypt parameter with the same algorithm as 4D uses to decrypt data (AES-256) and returns the result in decryptedBLOB.

You can use either a keyObject or a passPhrase to decrypt the BLOB:

keyObject: a JSON object containing the encryption key, with the same structure as the object returned by the New data key command
passPhrase: a string used to generate the encryption key

The number passed in the salt parameter of Decrypt data BLOB must match the one used for encryption.

If the decryption is successful, the decrypted data is returned in the decryptedBLOB parameter and the command returns True.

In case of error, the BLOB is returned empty and the command returns false.

Example

The following example shows how to decrypt an encrypted file located in the RESOURCES folder of the database:

 var $fileToDecrypt;$decryptedFile : 4D.File

 var $blobToDecrypt;$decryptedBlob : Blob

 var $result : Boolean

 

 $fileToDecrypt:=File("/RESOURCES/encryptedConfidential.txt")

 $decryptedFile:=File("/RESOURCES/decryptedConfidential.txt")

 

 $blobToDecrypt:=$fileToDecrypt.getContent()

 

 $result:=Decrypt data BLOB($blobToDecrypt;"myPassPhrase";MAXLONG;$decryptedBlob)

 $decryptedFile.setContent($decryptedBlob)

The passPhrase and salt used for decryption are identical to the passPhrase and salt used for encryption (see the Encrypt data BLOB example).