# What are the security of RSA?

The security of RSA are as follows −

• Plain text attacks

The plain-text attacks are classified into three subcategories are as follows −

Short message attack − In the short message attack, it can consider that attacker knows some blocks of plain text. If this assumption is true, the attackers can try encrypting each plain-text block to view if it results into the known cipher-text.

Therefore, it can avoid this short-message attack, it is suggested that it can pad the plain text before encrypting it.

Cycling attack

In this attacker suppose that the cipher text was acquired by doing some permutation on the plain-text in some manner. If this assumption is true thus the attacker can do the reverse procedure, which is to continuously do permutations on the known cipher text to try and acquire the original plain-text.

Unconcealed Message attack − It is discovered in theory that in the case of some very limited plain-text messages, encryption provides cipher-text which is the equal as the original plain-text. If this appears, the original plain-text message cannot be secret. Therefore, this attack is known as unconcealed message attack.

• Chosen cipher attack − In the chosen cipher attack, it can be able to discover out plain text based on cipher text using is known as the Extended Euclidean Algorithm.

• Factorisation attack − The entire security of RSA depends on the assumption that it is impossible for the attacker to factor the number N into two factors P and Q. If the attacker is able to discover out P or Q from the equation N = P x Q thus the attacker can discover out the private key.

It is supposing that N is at least 300 digits long in decimal terms, the attacker cannot discover P and Q simply. Therefore, the factorisation attack fails.

• Attack on the Encryption key − People well versed with the mathematics of RSA sometimes feel that it is quite easy because it can need a huge number for the public key or encryption key E.

It also creates RSA more secure. Therefore, if it can decide to try and create the working of RSA faster by utilizing a small value for E, it can lead to potential attacks known as attacks on the encryption key and therefore it is suggested that it can use E as 216 + 1 = 65537 or a value nearer to this number.

• Attacks on Decryption key − The attack on the decryption key are as follows −

• Revealed decryption exponent attack − If the attacker can anyway assumption the decryption key D, not only the cipher text produced by encryption the plain text with corresponding encryption key E are in danger, but even future messages are also in vulnerability. It can avoid this revealed decryption exponent attack, it is suggested that the sender uses new values for P, Q, N, and E as well.

• Low decryption exponent attack − It is fascinating to use a small value for decryption key D to create RSA work faster. This can provide the attacker in guessing the decryption key D by releasing the low decryption exponent attack.