Characteristics of Asymmetric Key Cryptography
Security Responsibility
- In asymmetric cryptography, the burden of security primarily falls on the receiver, like Bob.
- Bob must generate both a private and a public key, with the public key distributed to the community.
- Distribution occurs through a public-key channel, which doesn’t need secrecy but requires authentication and integrity to prevent impersonation.
Unique Key Pairs
- Bob and Alice can’t share the same key pair for two-way communication.
- Each entity in the community, including Bob and Alice, must create its own private and public keys.
- Alice uses Bob’s public key to encrypt messages to him, while she needs her own key pair for responses.
Key Management
- Bob needs only one private key to receive messages from anyone in the community.
- Alice, on the other hand, needs multiple public keys—one for each entity she communicates with.
- This means Alice requires a collection of public keys for effective communication.
Asymmetric Key Cryptography
In asymmetric Key cryptography, there are two keys, also known as key pairs: a public key and a private key. The public key is publicly distributed. Anyone can use this public key to encrypt messages, but only the recipient, who holds the corresponding private key, can decrypt those messages. “Public-key cryptography” is another representation used to refer to Asymmetric Key cryptography.
This cryptographic system addresses two major challenges faced in traditional (symmetric) cryptography: key distribution and digital signatures. Asymmetric algorithms use one key for encrypting data and another, related key for decrypting it. These algorithms possess an important feature:
- It’s impossible to figure out the decryption key just by knowing the encryption key and the cryptographic algorithm.
- Either of the two keys can be used for encryption, while the other is used for decryption.
Asymmetric-key cryptography uses mathematical functions to transform plaintext and ciphertext represented as numbers for encryption and decryption, while symmetric-key cryptography involves symbol substitution or permutation. In asymmetric-key cryptography, plaintext and ciphertext are treated as integers, requiring encoding and decoding processes for encryption and decryption.