On January 14,U. The crew module would weigh about 8. With a diameter of 5 metres as opposed to 3.
Or does security provide some very basic protections that we are naive to believe that we don't need? During this time when the Internet provides essential communication between literally billions of people and is used as a tool for commerce, social interaction, and the exchange of an increasing amount of personal information, security has become a tremendously important issue for every user to deal with.
There are many aspects to security and many applications, ranging from secure commerce and payments to private communications and protecting health care information. One essential aspect for secure communications is that of cryptography. But it is important to note that while cryptography is necessary for secure communications, it is not by itself sufficient.
The reader is advised, then, that the topics covered here only describe the first of many steps necessary for better security in any number of situations.
This paper has two major purposes. The first is to define some of the terms and concepts behind basic cryptographic methods, and to offer a way to compare the myriad cryptographic schemes in use today. The second is to provide some real examples of cryptography in use today.
Several companies, products, and services are mentioned in this tutorial. Such mention is for example purposes only and, unless explicitly stated otherwise, should not be taken as a recommendation or endorsement by the author. Some experts argue that cryptography appeared spontaneously sometime after writing was invented, with applications ranging from diplomatic missives to war-time battle plans.
It is no surprise, then, that new forms of cryptography came soon after the widespread development of computer communications.
In data and telecommunications, cryptography is necessary when communicating over any untrusted medium, which includes just about any network, particularly the Internet. There are five primary functions of cryptography today: Ensuring that no one can read the message except the intended receiver.
The process of proving one's identity. Assuring the receiver that the received message has not been altered in any way from the original. A mechanism to prove that the sender really sent this message. The method by which crypto keys are shared between sender and receiver.
In cryptography, we start with the unencrypted data, referred to as plaintext. Plaintext is encrypted into ciphertext, which will in turn usually be decrypted back into usable plaintext.
The encryption and decryption is based upon the type of cryptography scheme being employed and some form of key. For those who like formulas, this process is sometimes written as: In many of the descriptions below, two communicating parties will be referred to as Alice and Bob; this is the common nomenclature in the crypto field and literature to make it easier to identify the communicating parties.
If there is a third and fourth party to the communication, they will be referred to as Carol and Dave, respectively. A malicious party is referred to as Mallory, an eavesdropper as Eve, and a trusted third party as Trent.
Finally, cryptography is most closely associated with the development and creation of the mathematical algorithms used to encrypt and decrypt messages, whereas cryptanalysis is the science of analyzing and breaking encryption schemes.
Cryptology is the term referring to the broad study of secret writing, and encompasses both cryptography and cryptanalysis. For purposes of this paper, they will be categorized based on the number of keys that are employed for encryption and decryption, and further defined by their application and use.
The three types of algorithms that will be discussed are Figure 1: Uses a single key for both encryption and decryption; also called symmetric encryption.
Primarily used for privacy and confidentiality. Uses one key for encryption and another for decryption; also called asymmetric encryption. Primarily used for authentication, non-repudiation, and key exchange. Uses a mathematical transformation to irreversibly "encrypt" information, providing a digital fingerprint.
Primarily used for message integrity. Three types of cryptography: Secret Key Cryptography Secret key cryptography methods employ a single key for both encryption and decryption.
As shown in Figure 1A, the sender uses the key to encrypt the plaintext and sends the ciphertext to the receiver. The receiver applies the same key to decrypt the message and recover the plaintext.American Literature High School Curriculum.
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