Module 4 Case: Cryptography and Computer Forensics

Cryptographic and Computer Forensics
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Cryptographic and Computer Forensics (Case 4)
Part I
Symmetric and Asymmetric Cryptographic Algorithms
Most people believe that encryption only entails conversion of plaintext digital message to a ciphertext message using the same key for encryption and decryption. However, the truth of the matter is that there is more to encryption than this. As much as this assumption is correct, it only accounts for one form of a cryptographic algorithm, which is the use symmetric algorithm. Symmetric key cryptography is the most widely used algorithm when it comes to digital encryption messages, files, and software and as discussed above, it entails the use of the same public key to conducting both the encryption and decryption of digital messages (Villanueva, 2015). This fact, therefore, implies that the sender of the message should find a way of conveying the public key used for the message encryption to the message receiver or else the recipient of the message might fail to access the sent digital message or files. In most cases, the algorithm that is typically being used for symmetric key cryptography is the Advanced Encryption Standard (AES) (Cobb). This comprises of three forms of AES including AES- 128 that is sufficient to provide a SECRET level of protection to sensitive government information. The other two AES keys are preferred for providing TOP SECRET level of protection.
Besides the symmetric cryptography algorithm, the other form of encryption key algorithm that exists is the asymmetric key cryptography algorithm. Unlike the symmetric key cryptography, asymmetric cryptography entails the use of two different forms of keys for encryption and decryption of the digital message (Microsoft). This, therefore, entails that, two separate keys that are established when using an asymmetric cryptographic algorithm. The first is the private key that the sender of the message uses to encrypt the digital file before sending it to the recipient. However, unlike the case of symmetric cryptographic algorithm where the same key is used for encryption and decryption purposes, asymmetric cryptographic algorithm establishes a different key referred to as the public key that various recipients use for decryption purposes (Villanueva, 2015). The sender does not need to send the encryption key to the recipient as it is the case in the symmetric cryptographic algorithm.
Advantages and Disadvantages of Symmetric and Asymmetric Cryptographic Algorithm
One of the major assumptions that some investigators have heard is that asymmetric key algorithm encryption is tougher to crack compared to symmetric ones. This is probably because the lengths of asymmetric encryptions are longer compared to those of symmetric since they range from 1024 to 2048 while the symmetric ones lie between 128 to 256 (Cobb). However, the truth of the matter is that studies are yet to prove on whether the length of the keys can be used to determining their toughness. Also, experts have recommended that the best way of comparing the pros and cons of these two cryptographic algorithms be by considering their computational requirements as well as their efficiency regarding distribution.
Regarding computational requirements, symmetric cryptography is more advantageous to asymmetric since it requires fewer CPU cycles unlike the asymmetric key algorithm (Villanueva, 2015). This factor, therefore, implies that symmetric cryptographic algorithm is quicker to execute compared to asymmetric encryption. However, regarding providing security during the process of file transfer, symmetric key exhibits a greater disadvantage. This is because of the following reason. First, the recipient of the message might fail to access the sent file because he or she might not be having the key, which must be sent to him by the sender (Villanueva, 2015). Secondly, the chances are that the message might be tampered with during the transition period. This is because the security of the decryption key might be vulnerable depending on the channel through which it is delivered from sender to the recipient hence implying that should it fall into unauthorized hands the confidentiality of the encrypted message might lose its meaning, as it is likely to be accessed by unintended users.
The other disadvantage of symmetric key encryption is the difficulty in distributing the decryption key, especially when dealing with a larger population of users who are scattered all over the world. This is because ensuring that each receives the decryption key in a secure manner can be tiresome and maybe an impossible task (Villanueva, 2015). On the contrary, as much as this appears to be a disadvantage on the side of symmetric key encryption it on the other and exhibit itself as one of the advantages of asymmetric key encryption. This is because, with the asymmetric algorithm, it is difficult for an unauthorized user to decrypt an encrypted file since there is only one private key, which at all time remains with the sender (Cobb). This factor, therefore, implies that the security of the encrypted file is intact in asymmetric encryption compared to symmetric encryption.
The Hybrid Cryptography
To come up with a more secure file transfer system, new computer forensic experts have developed a hybrid form of cryptography, which combines both the symmetric and asymmetric key encryption process. During the process of executing a hybrid cryptographic encryption, the appropriate server establishes session keys (Villanueva, 2015). These keys are created through encryption of symmetric keys with the aid of an asymmetric key. It is, therefore, the resulting session keys that are used in encrypting the actual data, and they are only employed in a single session before being discarded. The fact that the session keys are only being used in single session expla...