MD5 is a non-reversible hash algorithm (although generally deprecated these days).
Marketo cannot non-reversibly hash data that must be retrieved and displayed to the user, by definition. This is the same for any app.
Hashing is used to protect data that does not ever need to be displayed, but simply compared to, such as passwords. For example, a site can tell whether the password you've just entered on a login page is or is not the same password they have stored + hashed; they can't read your password out of the system and tell it to you. By comparison, if First Names and Last Names were hashed, Marketo couldn't give you this data when you wanted it, they could only confirm that you had entered extant data. Quite useless as a marketing platform (though highly, er, secure).
Where is this question really coming from, though? Part of some audit?
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Anonymous
March 3, 2016
I have the same question - a client is demanding that we have that ability before we send a blast, but I can't find the answer anywhere here. Does anyone know if this is possible - even using a third party program?
The question, with respect, makes no sense. MD5, as you can read above, is non-reversible encryption: you cannot derive the original data. What data in Marketo would benefit from being stored in this way?
I would be happy to get on a call w/your client and hear what they're saying firsthand.
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Anonymous
March 3, 2016
Maybe I wasn't clear - they want to provide a MD5 Hash encrypted suppression file to ensure we don't mail to those they don't want to mail to. I'm of a mind to say we can't do this, but wanted to check first.