Question

Research the following:

Symmetric key vs. Asymmetric key

Public vs. Private

Pre-shared key?

Answer: Which one do you believe is more secure? and why. Are they equally secure? if not explain.

Answer 1

Cryptography: It is a method of using advanced mathematical principles or algorithms for transmitting data from sender to receiver securely.
A plain text from a user can be encrypted to a cipher text, then send through a communication channel and no eavesdropper can interfere with the plain text. When it reaches the receiver end, the cipher text is decrypted to the original plain text.
Encryption: It is a process whereby a message is encoded using encryption algorithm and a key in a format that cannot be read or understood by an eavesdropper.
Decryption: It is opposite to encryption process , means it is a process wherby the encoded message is decoded to plan text or real message.
Symmetrical Encryption: It involves one secret key to encrypt and decrypt the information. Symmetrical encryption is an old and best-known technique. It uses a secret key that can either be a number, a word or a string of random letters. The most widely used symmetric algorithm is AES-128, AES-192, and AES-256.

Asymmetrical Encryption: In this encryption a public key is made freely available to anyone who might want to send you a message. The second private key is kept a secret so that you can only know. Popular asymmetric key encryption algorithm includes EIGamal, RSA, DSA, Elliptic curve techniques, PKCS.

Difference between symmetric and asymmetric encryption:
Symmetric encryption uses a single key while asymmetrical encryption uses a pair of public key and a private key to encrypt and decrypt messages.
Symmetric encryption is an old technique while asymmetric encryption is relatively new.
Asymmetric encryption takes relatively more time than the symmetric encryption.

Symmetric vs Asymmetric key:
As we seen that in symmetric cryptography same secret key is used for encryption and decryption. Its a old technique and less secure.
Whereas in asymmetric cryptography different keys like message is encrypted by public key and decrypted by secret key. Its a new technique and more secure than symmetric.

Private and Public key: These are also similar to symmetric (private key) vs asymmetric one(public and private key combination).

Pre-Shared Key(PSK) : It can be thought of as a password that is shared with all parties using encryption to communicate. The PSK is the “password” used to encrypt / decrypt; in encryption such a “password” is called a key. The idea is that before communicating, the encryption key must be pre-shared with all necessary individuals. Once the password is know by undesired person the he can misutilised this key whenever he wants.

So as per my knowledge combination of private and public key which are used in Asymmetric cryptography is more secure because in this every time the message is secured with different public key and a secure private key is shared with recipients.

PFA screen shot of flow diagrams of symmetric and asymmetric cryptography.