how to verfy debian 7.0.1 DVDs?

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http://www.linuxquestions.org – hi, ..i used jigdo to download all DVDs of debian whezzy 7.0.1. now i want to verfy if they are correct and all trustworthy. which pgp key should i use to verfy the checksums? i read somewhere to download a bunch of keyfiles but i didnt really understand what i was doing... can anybody explaine how to do it even for me in a understandable way? and also maybe explaine what i am doing? thanks for any help! greets (HowTos)