(I forget if this was posted here last year, it sounds familiar.) Suppose I get a PGP-signed flaming message, full of insults, and at the end it says, sarcastically, "For a stupid moron, you've made some very nice postings." I could choose to excerpt this last part, "...you've made some very nice postings", and exhibit it in signed form. What I would do is to run the MD5 hash calculation on the first part of the message, saving the internal state of that calculation. I then publish just that MD5 state along with the rest of the message. Someone can check the signature by initializing their MD5 to that state, then running the algorithm on the part of the message I publish. This will end up with the signed MD5 value from the signature. The checker would know he was dealing with an excerpt, and that it came from the end of the message, but he would have know way of knowing what was in the part that was removed. Presently of course PGP has no mechanism to check such signature excerpts, but that could be added. Under some circumstances this might be a desirable feature. But people would have to be aware of the limitation that the excerptable portion would have to be the tail end of the message. Hal