22. The method of claim 21 , further comprising determining, in the at least one computing device, that the text unit is authentic based at least upon the digital signature attribute.
22. The method of claim 21 , further comprising determining, in the at least one computing device, that the text unit is authentic based at least upon the digital signature attribute. 23. The method of claim 22 , wherein determining that the text unit is authentic comprises validating the digital signature attribute using a public key.