Hi

Could someone explain to me in their unnderstading of encryption and hashing?

Both are broad topics. I recommend reading the Wikipedia entries on them. If you're so inclined, I also recommend Bruce Schneier's book Applied Cryptography.

If you have specific questions, ask 'em here.

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Briefly...

"Hashing" (in the cryptographic sense) is the process of creating a digital signature value. The purpose of the hash is to detect any change, even a change of a single bit within a multi-megabyte document. Furthermore, these algorithms are designed so that the resulting change in the hash-value will be completely unpredictable, and so that it is not possible to calculate what the "correct" hash-value would be for any document without actually hashing its entire content.

"Encryption" is designed to prevent recovery of document contents, unless you possess the exact key (or keys) that was used to encrypt it. These algorithms are designed so that, even if the key is incorrect by one single bit, the decryption will fail, and it will do so in a way that reveals nothing about the actual correct value of the key.

Both types of algorithms are designed to be public knowledge. There is no secret as to precisely how the Blowfish cipher works, or how the SHA1 hash algorithm works. Detailed analyses of the algorithms are also public, and there are constant "peer reviews." So... you can have a Blowfish-enciphered document, and therefore know exactly how it was prepared, and have a copy of the exact code that was used to do it... and if you do not have the key...

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