Cryptography

What is Cryptography?

The word cryptography in Greek means “secret writing.” However, the term today refers to the science and art of transforming messages to make them secure and immune to attacks. Figure shows the components involved in cryptography. The original message, before being transformed, is called plaintext. After the message is transformed, it is called ciphertext. An encryption algorithm transforms the plaintext to ciphertext; a decryption …

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Symmetric-Key Cryptography

Symmetric-Key Cryptography In symmetric-key cryptography, the same key is used by both parties. The sender uses this key and an encryption algorithm to encrypt data; the receiver uses the same key and the corresponding decryption algorithm to decrypt the data In symmetric-key cryptography, the algorithm used for decryption is the inverse of the algorithm used for encryption. This means that if the encryption algorithm uses a …

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Public-Key-Cryptography

Public-Key-Cryptography In public-key cryptography, there are two keys: a private key and a public key. The private key is kept by the receiver. The public key is announced to the public. Imagine Sender, as shown in Figure, wants to send a message to receiver. Sender uses the public key to encrypt the message. When the message …

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What is message security?

Message Security Let us first discuss the security measures applied to each single message. We can say that message security provides four services: privacy (confidentiality), message authentication, message integrity, and non-repudiation. Privacy Privacy means that the sender and the receiver expect confidentiality. The transmitted message must make sense to only the intended receiver. To all others. the message must be unintelligible. The …

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What is Digital Signature?

What is Digital Signature? Digital Signature We said that security provides four services in relation to a single message: privacy, authentication, integrity, and non-repudiation. We have already discussed privacy. The other three can be achieved by using what is called digital signature. The idea is similar to the signing of a document. When we send a document electronically, we can …

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What is user Authentication?

What is user Authentication? User Authentication The main issue in security is key management. However, key management involves user authentication. We, therefore, briefly discuss these issues.   User Authentication with Symmetric-Key Cryptography In this section, we discuss authentication as a procedure that verifies the identity of one entity for another. An entity can be a person, a process, a client, or a server; in our …

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What is Cryptography?

What is Cryptography? Cryptography is the science and art of transforming messages to make them secure and immune to attack. Cryptography is used to encryption renders a message unintelligible to unauthorized personnel. Decryption transforms an intentionally unintelligible message into meaningful information.   Cryptography algorithms are classified as either symmetric-key methods or public public-key methods. In symmetric key cryptography, the same secret key is used by the sender …

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