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Encryption software


Josh'Grizzly'Gregory
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I'm looking for a program to encrypt my external hard drive, I'm not a fan of saving stuff to my computer as it means that I have the hastle of trying to find a spare memory card to carry the data so I now use a portable hard drive.

I was curious as to if anyone knew of a good (possibly free) encryption software that I can use to encrypt the portable drive or even just password protect it.

Many thanks

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Most operating systems have built in systems these days. There will be plenty of free stuff out there - the standard one is Truecrypt if you feel the need to download something specific.

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Ah righty, wasn't aware that they already had one built in. Cheers guys I'll have a shufty at Truecrypt.

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If you have Windows 7 Ultimate or Vista Ultimate you can use the built-in BitLocker feature.

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I use, and would recommend PGP (Pretty Good Privacy)

You generate a secure and public key based on your email address and a passphrase, you can then send the public key to someone else, and you are then able to transfer encrypted files to another person either via email, web, usb or whatever.

As long as they have a copy of your public key then can decrypt and open the file.

PGP 8 was the final freeware version (Symantec bought the rights to it after that) and various versions of it can be downloaded here (For Vista and Win7, use the XP version). You're able to encrypt everything from a single file to a whole hard drive.

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I was going to recommend PGP (it is pretty much the defacto standard for public key data transfer) but was unsure of its setup for just encrypting files on your own disk.

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Truecrypt and PGP encryption are very different types of encryption used for different things. One is private key and one is public key encryption. Depending what the OP wants to do, they will want either public or private but rarely both will fit the requirements. If the OP wants to secure his/her HDD to prevent anyone else from accessing it should it be stolen, then you want truecrypt, bitlocker or other private key encryption implementation. PGP will not be useful here as it is assumed that the public key will not be secure. The idea of public key encryption is more to ensure the authenticity of a sender of a file and securing the communication channel than it is to keep the file absolutely confidential. This is where digital signatures, SSL etc come in.

In summary, if you want to make sure you HDD is confidential, use truecrypt, PGP isn't what you need.

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PGP will probably make use of normal encryption as well - if you send a file you don't encrpt the whole thing using asymmetric encryption, you do it normally and then transmit the key it has made up to encrypt it using public key encryption.

The mathsy reason for this is that you can only securely encrypt information smaller than the public key's size using public key encryption. Symmetrical (traditional) algorithms are also much quicker.

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The mathsy reason for this is that you can only securely encrypt information smaller than the public key's size using public key encryption.

How often would you want to encrypt something smaller than 256bits though?

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How often would you want to encrypt something smaller than 256bits though?

All the time... You encrypt a random value and then use that to symmetrically encrypt the message. So the private key doesn't decrypt the message, it decrypts the key which is then used to decrypt the message.

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All the time... You encrypt a random value and then use that to symmetrically encrypt the message. So the private key doesn't decrypt the message, it decrypts the key which is then used to decrypt the message.

Are you suggesting encrypting the salt value?

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Are you suggesting encrypting the salt value?

There wouldn't be a salt - you only use one of those to avoid rainbow tables for passwords that humans come up with and use all over the place - i.e. if I get your encrypted password and know the scheme I can use a precomputed table of words that have been through the same hashing scheme and come up with the password that way.

The point with public key encryption is that you don't care what the password that is used to encrypt the message is - no human will ever need to enter it.

Alice sends to Bob:

Alice's computer generates a random value as a key.

Alice's message is encrypted symmetrically with the key.

Alice signs the key with her private key and Bob's public key.

Alice sends the encrypted file and the encrypted key to Bob.

Bob decrypts the key with his private key and Alice's public key (this also lets him verify that Alice was indeed the sender).

Bob's computer decrypts the original message using the key.

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There wouldn't be a salt - you only use one of those to avoid rainbow tables for passwords that humans come up with and use all over the place - i.e. if I get your encrypted password and know the scheme I can use a precomputed table of words that have been through the same hashing scheme and come up with the password that way.

The point with public key encryption is that you don't care what the password that is used to encrypt the message is - no human will ever need to enter it.

Alice sends to Bob:

Alice's computer generates a random value as a key.

Alice's message is encrypted symmetrically with the key.

Alice signs the key with her private key and Bob's public key.

Alice sends the encrypted file and the encrypted key to Bob.

Bob decrypts the key with his private key and Alice's public key (this also lets him verify that Alice was indeed the sender).

Bob's computer decrypts the original message using the key.

I did a Computer Science degree, I understand the premise, but I still don't get what you are trying to say here?

All the time... You encrypt a random value and then use that to symmetrically encrypt the message. So the private key doesn't decrypt the message, it decrypts the key which is then used to decrypt the message.

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Aah - I put the order the wrong way around:

" You encrypt a random value and then use that to symmetrically encrypt the message. So the private key doesn't decrypt the message, it decrypts the key which is then used to decrypt the message."

Should read:

You use a random value to symmetrically encrypt the message and then encrypt the random value using public key encryption. So the private key doesn't decrypt the message, it decrypts the key which is then used to decrypt the message.#

Must try harder. Next we'll be covering onion skin routing...

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