Asymmetric Cryptography

What is the general process for message signing?

Message signing is a cryptographic process used to verify the authenticity and integrity of a message.

1. Hash creation: The sender generates a unique digital fingerprint (hash) of the message using a cryptographic hash function (e.g., SHA-256). This hash uniquely represents the message’s content.

2. Signing: The sender encrypts this hash with their private key, creating the digital signature. This ensures that the signature can only be generated by someone with access to the sender’s private key.

3. Sending: The digital signature is attached to the message, and both are sent to the recipient. The sender’s public key is also provided for verification.

4. Verification: The recipient uses the sender’s public key to decrypt the digital signature, retrieving the original hash.The recipient then generates a new hash from the received message and compares it with the decrypted hash. If they match, it confirms that the message has not been altered and verifies the sender’s identity.

What are the three functions of asymmetric encryption?

Asymmetric encryption, also known as public-key cryptography, serves several important functions in securing communications and data.

1. Encryption and decryption

2. Digital signatures

3. Key exchange

RSA

RSA, short for Rivest-Shamir-Adleman, is a widely used public-key cryptosystem for secure data transmission. It was named after its inventors, Ronald Rivest, Adi Shamir, and Leonard Adleman, who introduced it in 1977.

Diffie-Hellman

The Diffie-Hellman key exchange is a method used in cryptography to securely exchange cryptographic keys over a public channel. It was developed by Whitfield Diffie and Martin Hellman in 1976. The main purpose of the Diffie-Hellman key exchange is to enable two parties to securely develop a shared secret key that can be used for encrypting subsequent communications.

Digital Signature Algorithm (DSA)

The Digital Signature Algorithm (DSA) is a public-key cryptographic algorithm used to generate and verify digital signatures. It was proposed by the National Institute of Standards and Technology (NIST) in 1991 as part of the Digital Signature Standard (DSS).

How it Works

1. Key Generation: DSA generates a pair of keys: a private key for signing and a public key for verification.

2. Signing: The sender uses their private key to create a digital signature on a message. This signature is unique to both the message and the private key.

3. Verification: The recipient uses the sender’s public key to verify the authenticity of the signature and, consequently, the integrity and origin of the message.