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## The difference between SHA, AES and RSA algorithm?

Algorithm School

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Vlidda
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### The difference between SHA, AES and RSA algorithm?

Can anybody popularize the basic knowledge of algorithm?
Such as what is the difference between SHA, AES and RSA algorithm?

tay00000
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### Re: The difference between SHA, AES and RSA algorithm?

SHA -> digital data one way hashing.
AES -> digital content confidentiality protection via data scrambling.
RSA -> digital data confidentiality protection via data scrambling and also digital identity attestation and digital content verification via digital signatures.

bigWhite
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### Re: The difference between SHA, AES and RSA algorithm?

AES is a symmetric block cipher algorithm

RSA is an asymmetric encryption algorithm

Maggie
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### Re: The difference between SHA, AES and RSA algorithm?

I'm going to try to simplify things a little bit, and I'm going to introduce some metaphors that may not be appropriate, but hopefully will help you understand these three or these three types of algorithms.

SHA, digest algorithm.It can be imagined that a relatively large data block can be regarded as a whole, and the algorithm extracts the eigenvalues based on the whole data.Just like extracting a person's fingerprint can basically confirm a person's identity, when the summary value of a data block is correct, the integrity of the data can be confirmed.The algorithm can simplify the complexity of authentication system.However, it should be noted that the summary value is not unique to the original data block, and the summary data cannot be restored to the original data.The typical algorithm is also known as MD5.

AES symmetric algorithm, encryption key and decryption key the same.Used to encrypt a block of data and restore the original data using the key used at the time of encryption.It's as if two people each have the same key and can unlock the same lock.
See the following formula to understand symmetric encryption.
(the formula can use texture)
Encryption process E=f(T,K).Decryption process T=f(E,K).T plaintext, E ciphertext.
The typical algorithm is also known as DES and 3DES.

RSA asymmetric algorithm, encryption key and decryption key are different, is an important algorithm in PKI system.Let's take the example of opening the lock above. Two keys are different, so to speak, they are completely different, but they can open the same lock, which is not common in life, but you can try to understand it this way.Keys used to encrypt data can be different from keys used to decrypt data, an imaginative process that can be performed by a cryptographer and simplified to the function f.
(the formula can use texture)
E = f (T, pubK).Decryption process T=f(E,priK).PubK public key, priK private key.
Similar algorithms also have ECC.

kathysrazor
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### Re: The difference between SHA, AES and RSA algorithm?

SHA is what's called a compression function - it "compresses" data into smaller values that are hard to pull apart.

An example of this would be adding all the ASCII values in a string together. It gives you a value to represent the string, but the number can't easily be turned back into the original string (as many strings will have the same value).

SHA does the same basic thing, but in such a way that it's hard to predict what the output will be, and very hard to find an input that gives a particular output.

This means that you can do things like SHA a password to get a hash. When the user logs in, you SHA the password the user gives, compare, and see if they match.

AES and RSA are encryption algorithms. AES uses the same key to encrypt and decrypt. RSA has two different keys, public and private. Anything encrypted with the public key is decrypted with the private, and the other way around.

RSA is slow, particularly for large data. That's why we will often use RSA to protect an encryption key, then AES to protect the message. The receiver will use their private key to decrypt the message key, then use AES to decrypt the actual message.

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