In which of the following techniques the sender and receiver uses different key
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Definition: Cryptography is associated with the process of converting ordinary plain text into unintelligible text and vice-versa. It is a method of storing and transmitting data in a particular form so that only those for whom it is intended can read and process it. Cryptography not only protects data from theft or alteration, but can also be used for user authentication. Show
Description: Earlier cryptography was effectively synonymous with encryption but nowadays cryptography is mainly based on mathematical theory and computer science practice. Modern cryptography concerns with: Confidentiality - Information cannot be understood by anyone Integrity - Information cannot be altered. Non-repudiation - Sender cannot deny his/her intentions in the transmission of the information at a later stage Authentication - Sender and receiver can confirm each Cryptography is used in many applications like banking transactions cards, computer passwords, and e- commerce transactions. Three types of cryptographic techniques used in general. 1. Symmetric-key cryptography 2. Hash functions. 3. Public-key cryptography Symmetric-key Cryptography: Both the sender and receiver share a single key. The sender uses this key to encrypt plaintext and send the cipher text to the receiver. On the other side the receiver applies the same key to decrypt the message and recover the plain text. Public-Key Cryptography: This is the most revolutionary concept in the last 300-400 years. In Public-Key Cryptography two related keys (public and private key) are used. Public key may be freely distributed, while its paired private key, remains a secret. The public key is used for encryption and for decryption private key is used. Hash Functions: No key is used in this algorithm. A fixed-length hash value is computed as per the plain text that makes it impossible for the contents of the plain text to be recovered. Hash functions are also used by many operating systems to encrypt passwords. At PreVeil we often find ourselves explaining to our customers the concepts of how public and private keys work. We thought it would be helpful to discuss what these keys are, what they aren’t, and how they work. The blog below provides a general overview on public and private key pairs rather than an architectural overview of PreVeil. For a detailed understanding of PreVeil’s public-private key architecture, please check out our architectural whitepaper. How public and private key encryption worksPublic and private keys form the basis for public key cryptography , also known as asymmetric cryptography. In public key cryptography, every public key matches to only one private key. Together, they are used to encrypt and decrypt messages. If you encode a message using a person’s public key, they can only decode it using their matching private key. Public and private keys: an exampleBob wants to send Alice an encrypted email. To do this, Bob takes Alice’s public key and encrypts his message to her. Then, when Alice receives the message, she takes the private key that is known only to her in order to decrypt the message from Bob. Although attackers might try to compromise the server and read the message, they will be unable to because they lack the private key to decrypt the message. Only Alice will be able to decrypt the message as she is the only one with the private key. And, when Alice wants to reply, she simply repeats the process, encrypting her message to Bob using Bob’s public key.
The difference between public and private keysPublic keys have been described by some as being like a business’ address on the web – it’s public and anyone can look it up and share it widely. In asymmetric encryption, public keys can be shared with everyone in the system. Once the sender has the public key, he uses it to encrypt his message. Each public key comes paired with a unique private key. Think of a private key as akin to the key to the front door of a business where only you have a copy. This defines one of the main differences between the two types of keys. The private key ensures only you can get through the front door. In the case of encrypted messages, you use this private key to decrypt messages Together, these keys help to ensure the security of the exchanged data. A message encrypted with the public key cannot be decrypted without using the corresponding private key. Generating public and private keysThe public and private key are not really keys but rather are really large prime numbers that are mathematically related to one another. Being related in this case means that whatever is encrypted by the public key can only be decrypted by the related private key. A person cannot guess the private key based on knowing the public key. Because of this, a public key can be freely shared. The private key however belongs to only one person. There are several well-known mathematical algorithms that are used to produce the public and private key. Some well-respected algorithms include:
Summary Public key cryptography Public key cryptography provides the basis for securely sending and receiving messages with anyone whose public key you can access. Public keys enable:
Private keys enable:
Public-private key encryption: Real world examplesDigital signaturesPublic and private keys can also be used to create a digital signature. A digital signature assures that the person sending the message is who they claim to be. Typically, we use the recipient’s public key to encrypt the data and the recipient then uses their private key to decrypt the data. However, using the scheme of digital signatures, there’s no way to authenticate the source of the message. Mike could get a hold of Alice’s public key (since it’s public) and pretend that Bob is the person sending a message to Alice. To create a digital signature, Bob digitally signs his email to Alice using his private key. When Alice receives the message from Bob, she can verify the digital signature on the message came from Bob by using his public key. As the digital signature uses Bob’s private key, Bob is the only person who could create the signature. PreVeil’s method for securing messages is a bit more complex than the example provided above. However, the example provides a good general overview for how asymmetric encryption works.  Diffie-Helman key exchangeThe Diffie Hellman key exchange demonstrates an example of how users can securely exchange cryptographic keys over a public channel. In the past, secure encrypted communication required that the individuals first exchange keys by a secure means such as paper key lists transported by a trusted courier. The Diffie–Hellman key exchange method allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure channel. PreVeil uses the Diffie Hellman key exchange to enable Web PreVeil. Web PreVeil is a browser based end-to-end encrypted email service that allows users to easily access their secure email account on the web without any software download or any passwords to remember. Here’s a video to explain how this works: Business benefits of public private key encryption
Confidentiality is ensured because the content that is secured with the public key can only be decrypted with the private key. This ensures that only the intended recipient can ever review the contents Integrity is ensured because part of the decryption process requires checking that the received message matches the sent message. This ensures that the message has not been changed in between. Authenticity is ensured because each message sent by Alice to Bob is also signed by Alice’s private key. The only way to decrypt Alice’s private key is with her public key, which Bob can access. By signing the message with her private key, Alice ensures the authenticity of the message and shows that it really did come from her. ConclusionPublic and private key pairs form the basis for very strong encryption and data security. If you are interested in reading more about public and private keys, take a look at the following articles: In which encryption techniques only one key is used by sender and receiver?1. Secret key cryptography (symmetrical encryption): Both the sender and receiver must use the same key to encrypt and decrypt messages being sent.
When sender and recipient have different key it is called?Asymmetric cryptography involves a pair of keys to encrypt and decrypt data. The two participants in the asymmetric encryption workflow are the sender and the receiver.
What method that requires the sender and the receiver to have access to the same key?Symmetric encryption is also known as private-key cryptography or secret key algorithm and requires both the parties of sender and receiver to have access to the same key to decrypt the data.
What is the type of encryption where the sender and receiver use the same key to encrypt and decrypt information?In symmetric encryption the same key is used for encryption and decryption. It is therefore critical that a secure method is considered to transfer the key between sender and recipient.
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