Cryptography, a cornerstone of data privacy, is the practice and study of techniques to secure communication and information from adversaries. It involves creating written or generated codes that allow information to be kept secret. Cryptography not only protects data from theft or alteration but can also be used for user authentication.
Historically, cryptography was synonymous with encryption, converting information from a readable state to apparent nonsense. The origin of cryptography is usually dated from about 2000 BC, with the Egyptian practice of hieroglyphics. These were not designed to conceal meaning but to elevate the status of the inscriber or the message.
Types of Cryptography
There are several ways of classifying cryptographic algorithms. For purposes of this glossary, they will be categorised based on the number of keys that are employed for encryption and decryption and further defined by their application and use.
The three types of algorithms that will be discussed are Secret Key Cryptography (SKC), Public Key Cryptography (PKC), and Hash Functions.
Secret Key Cryptography (SKC)
Secret Key Cryptography methods employ a single key for both encryption and decryption. Also known as symmetric encryption, it is said to be 'secure' because the unencrypted text cannot be derived without access to the key. This method is useful for bulk data encryption and secure data transmission over the Internet.
However, the challenge of this method lies in the key exchange problem. If the key is disclosed to the outsider, the purpose of cryptography is defeated. The strength of secret key cryptography lies in the secrecy of the key.
Public Key Cryptography (PKC)
Public Key Cryptography, also known as asymmetric cryptography, uses two mathematically linked but not identical keys—a public key and a private key. The public key encrypts the message, whereas the private key decrypts it. This method has the main advantages of increased security and convenience: the private key does not need to be passed across the Internet.
The disadvantage is that it is slower than symmetric encryption and requires more computational resources. It is commonly used in applications such as secure email, digital signatures, and SSL/TLS for securing web traffic.
Applications of Cryptography
Cryptography is used in many applications that people use daily. Banking transactions, computer passwords, and secure websites all use cryptography to keep information secure.
However, cryptography is not just for securing personal data. It is also used for secure communication in the military, government, and other organisations to protect information, operations, and identities.
Secure Communication
Ensuring secure communication is of utmost importance. Cryptography is used to ensure that the communication between two parties remains confidential. It is also used to authenticate the identity of the communicating parties.
Secure communication is necessary for all kinds of digital transactions, such as those involving banks, credit card companies, and online retail or auction sites. It is also used in secure email communication, secure browsing, and private messaging apps.
Data Integrity
Data integrity refers to the accuracy and consistency of data. Cryptography is used to ensure that data is not modified in transit and that the original message sent is the same as the message received.
Hash functions are commonly used to ensure data integrity. They take an input and return a fixed-size string of bytes, typically a 'digest.' The same input will always produce the same output, which is unique to the input data. This allows any changes to the data to be easily identified.
Challenges in Cryptography
Despite its advantages, cryptography is not a silver bullet for data security. There are several challenges that need to be addressed to ensure that the cryptographic measures are effective.
These challenges include key management, computational resources, and the constant evolution of cryptographic attacks.
Key Management
Key management is one of the most difficult aspects of cryptography. The security of the system depends on the security of the keys. If the keys are lost, the data is lost. If the keys are stolen, the data can be decrypted by unauthorised parties.
Key management includes the generation, exchange, storage, use, and replacement of keys. It also includes the procedures for handling and protecting the keys.
Computational Resources
As mentioned earlier, some cryptographic methods require significant computational resources. This can be challenging in systems with limited resources, such as embedded systems or older hardware.
Furthermore, as computers' computational power increases, the length of the keys needed to provide adequate security also increases. This can lead to longer encryption and decryption times and increased resource usage.
Evolution of Cryptographic Attacks
As cryptographic systems evolve, so do the attacks on them. Cryptographers must constantly stay ahead of attackers by developing new methods and improving existing ones.
Some of the common types of cryptographic attacks include ciphertext-only attacks, known-plaintext attacks, chosen-plaintext attacks, and chosen-ciphertext attacks. Each requires a different defence approach.
Conclusion
Cryptography is vital to data privacy and is used in many aspects of daily life. Despite its challenges, it provides a robust method for securing data and communication.
As technology continues to evolve, the field of cryptography will continue to grow and adapt. The future of cryptography will likely involve quantum cryptography, post-quantum cryptography, and the ongoing development of new cryptographic algorithms and methods.
