Encrypt data BLOB

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4D v20 R7

Encrypt data BLOB


Encrypt data BLOB ( blobToEncrypt ; keyObject \| passPhrase ; salt ; encryptedBLOB ) -> Function result

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

Description

The Encrypt data BLOB command encrypts the blobToEncrypt parameter with the same algorithm as 4D uses to encrypt data (AES-256) and returns the result in encryptedBlob.

You can use either a keyObject or a passPhrase to encrypt 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

Pass in salt a number that will be used to make the encryption more robust.

If the encryption is successful, the encrypted data is returned in the encryptedBlob parameter and the command returns True.

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

Note: When you encrypt a blob using Encrypt data BLOB, the resulting encryptedBlob is a multiple of 16 bytes because of the encryption algorithm. As a consequence, if blobToEncrypt is not a multiple of 16 bytes, the command automatically turns it into a multiple of 16 bytes by adding null bytes at the end. To avoid errors when decrypting the blob with Decrypt data BLOB, you need to handle the size of blobToEncrypt when working with files other than text files. For a detailed example on how to do this, see this blog article.

Example

Encrypt a text file located in the RESOURCES folder of the database:

 var $fileToEncrypt;$encryptedFile : 4D.File

 var $blobToEncrypt;$encryptedBlob : Blob

 var $result : Boolean

 

 $fileToEncrypt:=File("/RESOURCES/confidential.txt")

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

 

 $blobToencrypt:=$fileToEncrypt.getContent()

 

 $result:=Encrypt data BLOB($blobToEncrypt;"myPassPhrase";MAXLONG;$encryptedBlob)

 $encryptedFile.setContent($encryptedBlob)