What s the difference between SHA and AES encryption

Question

User · Accepted Answer

SHA isn t encryption  it s a one-way hash function  AES  Advanced Encryption Standard  is a symmetric encryption standard   AES Reference

User · Answer

SHA is a hash function and AES is an encryption standard  Given an input you can use SHA to produce an output which is very unlikely to be produced from any other input  Also  some information is lost while applying the function so even if you knew how to produce an input yielding the same output  that input wouldn t likely be the same one used in the first place  On the other hand AES is meant to protect from disclosure to third parties any data sent between two parties sharing the same encryption key  This means that once you know the encryption key and the output  and the IV     you can seamlessly get back to the original input  Please notice that SHA doesn t require anything but an input to be applied  while AES requires at least 3 thins  what you re encrypting decrypting  an encryption key and the initialization vector  IV

User · Answer

SHA doesn t require anything but an input to be applied  while AES requires at least 3 things - what you re encrypting decrypting  an encryption key  and the initialization vector

User · Answer

SHA is a family of  Secure Hash Algorithms  that have been developed by the National Security Agency  There is currently a competition among dozens of options for who will become SHA-3  the new hash algorithm for 2012    You use SHA functions to take a large document and compute a  digest   also called  hash   of the input  It s important to realize that this is a one-way process  You can t take a digest and recover the original document   AES  the Advanced Encryption Standard is a symmetric block algorithm  This means that it takes 16 byte blocks and encrypts them  It is  symmetric  because the key allows for both encryption and decryption   UPDATE  Keccak was named the SHA-3 winner on October 2  2012

User · Answer

SHA stands for Secure Hash Algorithm while AES stands for Advanced Encryption Standard  So SHA is a suite of hashing algorithms  AES on the other hand is a cipher which is used to encrypt  SHA algorithms  SHA-1  SHA-256 etc     will take an input and produce a digest  hash   this is typically used in a digital signing process  produce a hash of some bytes and sign with a private key

User · Answer

SHA and AES serve different purposes   SHA is used to generate a hash of data and AES is used to encrypt data   Here s an example of when an SHA hash is useful to you   Say you wanted to download a DVD ISO image of some Linux distro   This is a large file and sometimes things go wrong - so you want to validate that what you downloaded is correct   What you would do is go to a trusted source  such as the offical distro download point  and they typically have the SHA hash for the ISO image available   You can now generated the comparable SHA hash  using any number of open tools  for your downloaded data   You can now compare the two hashs to make sure they match - which would validate that the image you downloaded is correct   This is especially important if you get the ISO image from an untrusted source  such as a torrent  or if you are having trouble using the ISO and want to check if the image is corrupted   As you can see in this case the SHA has was used to validate data that was not corrupted   You have every right to see the data in the ISO   AES  on the other hand  is used to encrypt data  or prevent people from viewing that data with knowing some secret   AES uses a shared key which means that the same key  or a related key  is used to encrypted the data as is used to decrypt the data   For example if I encrypted an email using AES and I sent that email to you then you and I would both need to know the shared key used to encrypt and decrypt the email   This is different than algorithms that use a public key such PGP or SSL   If you wanted to put them together you could encrypt a message using AES and then send along an SHA1 hash of the unencrypted message so that when the message was decrypted they were able to validate the data   This is a somewhat contrived example   If you want to know more about these some Wikipedia search terms  beyond AES and SHA  you want want to try include   Symmetric-key algorithm   for AES  Cryptographic hash function   for SHA  Public-key cryptography  for PGP and SSL

[encryption] What's the difference between SHA and AES encryption?

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