Reference > Functions reference > Container functions > CryptAuthCode
 
CryptAuthCode
Purpose 
Returns a binary HMAC (keyed-hash message authentication code) using the specified cryptographic hash algorithm.
Format 
CryptAuthCode(data;algorithm;key)
Parameters 
data - any text expression or field from which to generate the HMAC.
algorithm - the name of the cryptographic algorithm to use (see below).
key - any expression or field as the key to encode the hash with.
Data type returned 
container
Originated in 
FileMaker Pro 16.0
Description 
Use the Base64EncodeRFC and Base64Decode or HexEncode and HexDecode functions to control the encoding of the key and the returned HMAC.
For the algorithm parameter, use one of the following names to specify the cryptographic algorithm:
MD5
MDC2
SHA
SHA1
SHA224
SHA256
SHA384
SHA512
If algorithm is empty (""), the SHA512 algorithm is used; an unrecognized name causes this function to return "?".
Notes 
This function is not supported in runtime solutions and returns "?".
Example 1 
In the Results container field, stores a file containing an HMAC of the text in the Message field. The HMAC is encoded with the value in the Key field using the default algorithm.
Set Field [ Table::Results ; CryptAuthEncode ( Table::Message ; "" ; Table::Key ) ]
Example 2 
Returns an HMAC of the contents of the $JSON variable using the SHA512 algorithm and a hex-encoded key $Key. The container data returned by CryptAuthCode is returned as Base64-encoded text.
Base64EncodeRFC ( 4648; CryptAuthCode ( $JSON ; "SHA512" ; HexDecode ( $Key ; ".key" ) )
Related topics 
Functions reference (category list)
Functions reference (alphabetical list)
About formulas
About functions
Defining calculation fields
Using operators in formulas