Public Key Encription
1) How does the public key cryptography work? Explain in detail?
1. Public-key, what it is
Public-key refers to a cryptographic mechanism. It has been named public-key to differentiate it from the traditional and more intuitive cryptographic mechanism known as: symmetric-key, shared secret, secret-key and also called private-key.
Symmetric-key cryptography is a mechanism by which the same key is used for both encrypting and decrypting; it is more intuitive because of its similarity with what you expect to use for locking and unlocking a door: the same key. This characteristic requires sophisticated mechanisms to securely distribute the secret-key to both parties2.
Public-key on the other hand, introduces another concept involving key pairs: one for encrypting, the other for decrypting. This concept, as you will see below, is very clever and attractive, and provides a great deal of advantages over symmetric-key:
• Simplified key distribution
• Digital Signature
• Long-term encryption
However, it is important to note that symmetric-key still plays a major role in the implementation of a Public-key Infrastructure or PKI.
1.1 A definition
Public-key is commonly used to identify a cryptographic method that uses an asymmetric-key pair3: a public-key and a private-key 4. Public-key encryption uses that key pair for encryption and decryption. The public-key is made public and is distributed widely and freely. The private-key is never distributed and must be kept secret.
Given a key pair, data encrypted with the public-key can only be decrypted with its privatekey; conversely, data encrypted with the private-key can only be decrypted with its publickey. This characteristic is used to implement encryption and digital signature. Both encryption and digital signature principles are illustrated in Figure 1 and Figure 2.
1.2 Encryption and Decryption
Encryption is a mechanism by which a message is transformed so that only the sender and
1. Public-key, what it is
Public-key refers to a cryptographic mechanism. It has been named public-key to differentiate it from the traditional and more intuitive cryptographic mechanism known as: symmetric-key, shared secret, secret-key and also called private-key.
Symmetric-key cryptography is a mechanism by which the same key is used for both encrypting and decrypting; it is more intuitive because of its similarity with what you expect to use for locking and unlocking a door: the same key. This characteristic requires sophisticated mechanisms to securely distribute the secret-key to both parties2.
Public-key on the other hand, introduces another concept involving key pairs: one for encrypting, the other for decrypting. This concept, as you will see below, is very clever and attractive, and provides a great deal of advantages over symmetric-key:
• Simplified key distribution
• Digital Signature
• Long-term encryption
However, it is important to note that symmetric-key still plays a major role in the implementation of a Public-key Infrastructure or PKI.
1.1 A definition
Public-key is commonly used to identify a cryptographic method that uses an asymmetric-key pair3: a public-key and a private-key 4. Public-key encryption uses that key pair for encryption and decryption. The public-key is made public and is distributed widely and freely. The private-key is never distributed and must be kept secret.
Given a key pair, data encrypted with the public-key can only be decrypted with its privatekey; conversely, data encrypted with the private-key can only be decrypted with its publickey. This characteristic is used to implement encryption and digital signature. Both encryption and digital signature principles are illustrated in Figure 1 and Figure 2.
1.2 Encryption and Decryption
Encryption is a mechanism by which a message is transformed so that only the sender and