Creates an encryption key and initialization vector, which can be used for AES encryption and decryption.
Encr_AES_CreateKeyAndIV ( switches ; passphrase ; salt )
|switches||modifies the behavior of the function|
|passphrase||the passphrase (password) to use|
|salt||a random text to make encryption more secure, make this 8 to about 20 characters long|
Switches must be one of:
|-KeySize=256||(default) create a key for AES-256 encryption|
|-KeySize=128||create a key for AES-128 encryption|
Other switches are not (yet) possible.
Data type returned
the created key and the IV each on a separate line. The function can also return an error code. Returned error codes can be:
|$$-4244||kErrPwdEmpty||no passphrase was given|
|$$-50||paramErr||Parameter error (incorrect key size given)|
Troi Encryptor Plug-in 3.0
FileMaker Pro 14 to 17
This is an advanced function, for exchanging data with other systems. You might want to use the more simple Encr_EncryptAES function.
You use this in conjunction with the Encr_AES_EncryptUsingKey and Encr_AES_DecryptUsingKey functions.
Make the random salt 8 to about 20 characters long (1000 chars is the maximum).
The key is derived from a SHA1 hash of the salt and the passphrase.
You can use AES-128 or AES-256.
AES-128: 128 bit, CBC with a 16 byte key. Blocksize is 16 byte so the IV generated is 16 byte.
AES-256: 256 bit, CBC with a 32 byte key. Blocksize is also 16 byte so the IV generated is 16 byte.
Set Variable [ $KeyAndIV ; Encr_AES_CreateKeyAndIV ( "-KeySize=256" ; "mySecretKey" ; "bZz%gABQ6lBpfNwgeD?v" ) ]
This will return the encryption key and the initialization vector each on a separate line, the result will be similar to:
The 2 lines are encoded as base64.
For AES-128 the key and initialization vector are 16 bytes.
For AES-256 the key is 32 bytes and initialization vector is 16 bytes long.
With the passphrase and the random salt you can generate the key and the initialization vector suitable for AES-256 encryption. You can use these script steps:
Set Variable [ $Passphrase ; YourPassphraseField // get the passphrase from a field. ] # set the salt; this should be a random string. Set Variable [ $UseFixedTestSalt ; Value:0 ] # Generate a 20 character random salt Loop Set Variable [ $RandomChar ; Let ( allowedChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890!@#$%&*+?" ; Middle ( allowedChars ; Int ( Random * Length ( allowedChars ) ) + 1 ; 1 ) ) ] Set Variable [ $Salt ; $Salt & $RandomChar ] Exit Loop If [ Length ( $Salt ) >= 20 ] End Loop End If # Set the wanted keysize: The sizes are given in bits... # ... This is a key of 32 byte and IV of 16 byte. Set Variable [ $Switches ; "-KeySize=256" ] # Generate the key now: Set Variable [ $KeyAndIV ; Value : Encr_AES_CreateKeyAndIV ( $Switches ; $Passphrase ; $Salt ) ] If [ Left ( $KeyAndIV ; 2 ) = "$$" ] Set Field [ this::gErrorCode ; $KeyAndIV ] Perform Script [ “ Handle Errors” ] Else Set Field [ this::gErrorCode ; 0 ] # NOTE the result is on two lines: first the key and the IV on the next line. # The key and IV are Base64 encoded. Set Variable [ $Key ; Value : Left ( $KeyAndIV ; Position ( $KeyAndIV ; "¶" ; 1 ; 1 ) - 1 ) ] Set Variable [ $IV ; Value : Middle ( $KeyAndIV ; Position ( $KeyAndIV ; "¶" ; 1 ; 1) + 1 ; Length ( $KeyAndIV ) ) ]
Now the key + IV are generated, you can encrypt data with the Encr_AES_EncryptUsingKey function.