INTEGRITYDIGEST Verification

[grantyn]

I occasionally get a KeyError on INTEGRITYDIGEST in the iine 397 of EyeFiServer.py:

395: verifiedDigest = eyeFiCrypto.calculateIntegrityDigest(untrustedFile.getvalue(),
396: self.server.eyeFiConfiguration['Card']['UploadKey'])
397: unverifiedDigest = form['INTEGRITYDIGEST'][0]

I've coded a try/except block to catch the KeyError, but am wondering why this happens.