Will convert the string to a UTF8-encoded string stored in Base64 format.

When sending Base64 as a URL parameter, / and + will not survive - it is common to do this: StringToBase64.Replace('/','_').Replace('+','-')

Chances are that the receiver will use this frequently used replacement pattern and understand the data. See this SO article for background

If you have a string in clear text and want it as a byte array (BLOB), do this: 'My clear text string'.StringToBase64.Base64ToBlob

When sending SAML tokens - and possibly other things - you are expected to compress the data with Deflate. You can follow a pattern to access the Deflate mechanism in Turnkey. Read more here: SysSingleton.Deflate