- When using symmetric algorithms, both parties share the same key for en- and decryption. To provide privacy, this key needs to be kept secret. Once somebody else gets to know the key, it is not safe any more. Symmetric algorithms have the advantage of not consuming too much computing power. Asymmetric algorithms use pairs of keys. One is used for encryption and the other one for decryption. The decryption key is typically kept secretly, therefore called private key or secret key, while the encryption key is spread to all who might want to send encrypted messages, therefore called public key. Everybody having the public key is able to send encrypted messages to the owner of the secret key.
- For symmetric encryption, it only use a one key to encrypt and decrypt message. Also there is standard pattern to move the each bit of the key. For example, there is Caesar cipher which is shift cipher. What it does is that replace each letter with plus 3 mod 26. Then “Attack at dawn” becomes "Dwwdfn dw gdzq." Like this example, there is a pattern to crack the message.
For asymmetric encryption, there are two keys which are a public key and private key. When A make a priavte key, then A can encrypt the message. Also, A can create a public key to show everyone. The important issue is that only A can decode the message because only A knows the private key.
- For symmetirc encryption, if a sender know the key, he/she can encrypt and decrypt the message. If not, he/she can not do anything with the message. The reason is that there is one key which is a secret key. Therefore, depend on a sender who know the key or not, we can identify him/her. For asymmetic encryption, if a person encrypts the message with his private key, and send to other poeple with public key. They can see the public key, but they can not decode the message because they do not his/her private key. However, they can know who encrypt the message.
advantage of symmetirc encrpytion
1) all user share the key
2) very fast and secure
disadvantage of symmetric encrpytion
1) particularly in one-shot communications
2) not easy to give a key to other people
advantage of asymmetric encrpytion
1) key distribution simplified
disadvantage of asymmetric encrytion
1) encryption/decryption much slower
2) much larger keys needed
3) spoofing of public keys
1 comment:
Good post. This article provides a quick overview about symmetric and asymmetric form of encryption. You have also mentioned advantages and disadvantages of both these techniques. All these points can help one to know which is the best technique.
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