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Cryptography

  • Cryptography is the way of securing information with the use of codes so that only those persons for whom the information is meant to understand can understand it.
  • It prevents unauthorized access to the sensitive data
  • Word origin:
  • “Crypt”: Hidden
  • “Graphy”: Writing
  • It relies on mathematical concepts and rules that are based on algorithms to transform messages into unreadable formats.
  • Features of Cryptography:
  • Confidentiality: Information can only be accessed by the intended person.
  • Integrity: Information cannot be modified in the stage of storage or transition between the sender and receiver.
  • Non-repudiation: The Sender cannot deny the sent information.
  • Authentication: The identities of both the sender and receiver are verified, along with confirmation of the source and destination of the information.
  • Interoperability: It allows for secure communication between different systems and platforms.
  • Adaptability: It continuously evolves to stay ahead of security threats and technological advancements.

Types of Cryptography:

  • Symmetric Key Cryptography:
  • Sender and receiver of a message use a single common key to encrypt and decrypt messages.
  • Fast and simple
  • Sender and Receiver have to exchange key securely.
  • Popular symmetric key cryptography systems: Data Encryption System(DES) and Advanced Encryption System(AES).
  • Hash functions:
  • No usage of any key in this algorithm.
  • A hash value with a fixed length is calculated as per the plain text.
  • It makes impossible for the contents of plain text to be recovered.
  • Many operating systems use hash functions to encrypt password.
  • Asymmetric Key Cryptography:
  • A pair of keys is used to encrypt and decrypt information.
  • Sender’s public key is used for encryption and a receiver’s private key is used for decryption.
  • Public key and Private keys are different.
  • Even if the public key is known by everyone the intended receiver can only decode it.
  • The most popular asymmetric key cryptography algorithm is the RSA algorithm.
Hash functions

Hash functions - TCP Handbook

Applications of Cryptography

  • Computer passwords:
  • Used in computer security when creating and maintaining passwords.
  • When the user logs in their password is hashed and compared to the hash that was previously stored.
  • Password are hashed and encrypted so that even if a hacker gain access to the password database they can not read the passwords.
  • Digital Currencies:
  • To protect transactions and prevent frauds, digital currencies like Bitcoin also use cryptography.
  • Complex algorithm and cryptographic key are used.
  • It makes harder to tamper with or forge the transactions.
  • Secure web browsing:
  • Public key cryptography is used by the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols to encrypt data sent between the web server and the client.
  • Electronic Signatures:
  • They are created using cryptography and can be validated using public key cryptography.
  • Electronic signatures are enforceable by law and their use is expanding quickly.
  • Authentication:
  • Used in situations like accessing a bank account, logging into a computer or using a secure network.
  • They are employed by authentication protocols to confirm the user’s identity and confirm that they have the required access rights to the resources.
  • Cryptocurrencies:
  • Heavily used by cryptocurrencies like Bitcoin and Ethereum to protect transactions, thwart fraud, and maintain network’s integrity.
  • Complex algorithms and cryptographic keys are used to protect transactions, making it harder to tamper with or forge the transactions.
  • End-to-end Internet Encryption:
  • Used to protect two-way communications like video conversations, messages and email.
  • Widely used in communication apps like WhatsApp and Signal and it provides a high level of security and privacy for users.

Types of Cryptography Algorithm:

  • Advanced Encryption Standards (AES):
    • Uses the same key for encryption and decryption.
    • Symmetric block cipher algorithm with block size of 128 bits, 192 bits or 256 bits.
    • AES algorithm is widely regarded as the replacement of DES (Data encryption standard) algorithm.
  • RSA:
    • Basic asymmetric cryptographic algorithm which uses two different keys for encryption.
    • RSA algorithm works on a block cipher concept that converts plain text into cipher text and vice versa.
  • Secure Hash Algorithm (SHA):
    • Used to generate unique fixed-length digital fingerprints of input data known as hashes.
    • SHA-2 and SHA-3 are commonly used.
✔ Learning Tip

Experiment with different security tools to understand their strengths and limitations.