Back -Doors. Using multiple ciphers

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Back -Doors. Using multiple ciphers
Topic Started: Jul 28 2009, 10:11 AM (74 Views)
lalande21185	Jul 28 2009, 10:11 AM Post #1
Just registered Posts: 1 Group: Members Member #3,278 Joined: July 27, 2009	Hi everyone Just found this site yesterday so first post. Regarding Government and Cryptography. Can the NSA as well as other government agencies ( I am from the UK but use the NSA as so well known), break (Hack) into all our communications? With so much software out there, how many have back doors so that these agencies can get our keys to read our messages? If time was not a factor in encrypting your data, surely you could pick the 6 best ciphers (AES · Blowfish · DES · Triple DES · Serpent · Twofish) for example, and use each one in a certain order to encrypt your data, so your encrypted data is re-encrypted again and again. Or just pick 2 or 3. Surely this way would make it much more secure. This would be secure and no amount of hardware or software would ever be able to go through all the keys and break the cipher. Karl Edited by lalande21185, Jul 28 2009, 10:11 AM.



osric	Jul 31 2009, 07:10 PM Post #2
Member Posts: 46 Group: Members Member #3,254 Joined: March 15, 2009	When you are thinking about the security of your cipher, you also have to think about managing the keys, first so that they are kept secure and second so that you can distribute them securely. This feature often becomes the central consideration. The more complex the encipherment (like re-enciphering 6 times) the more keys you have to use and the bigger is the task of disseminating the keys to all users while keeping them secure. This is not a factor if you just want to encipher things to store safely on your own computer. But it is a major factor if you are talking about a network of users, which is sending messages every day. Here you have to keep changing the keys, which means you have to keep sending them securely to all the network members. Now simplicity is at a premium. An example from the 2nd World War of key compromise was the German Diplomatic cipher, which was a One Time Pad. In theory unbreakable. In practice a German courier delivered some of the keys by mistake to an overseas British Embassy. And the US relieved a Japanese courier of other keys as he travelled from Germany back to Japan through the Panama canal. These are the sort of unforeseen events that happen in life, and undermine an otherwise secure cipher. So coming back to your example, it's probably best in a real-life situation involving many users and many messages, to choose one of the secure ciphers you mention and then focus on getting the keys safely to all users.



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