LECTURE 3 (27 July 2009)
This week I learn about Cryptography Concept. Before that I must know what is Cryptography. Cryptography is the art and science of keeping data secure. Cryptographic services help ensure data privacy, maintain data integrity, authenticate communicating parties, and prevent repudiation (when a party refutes having sent a message).
Basic encryption allows you to store information or to communicate with other parties while preventing non-involved parties from understanding the stored information or understanding the communication. Encryption transforms understandable text (plaintext) into an unintelligible piece of data (ciphertext). Decryption restores the understandable text from the unintelligible data. Both functions involve a mathematical formula (the algorithm) and secret data (the key).
Cryptographic algorithms
There are two types of cryptographic algorithms:
1. With a secret or symmetric key algorithm, the key is a shared secret between two communicating parties. Encryption and decryption both use the same key. The Data Encryption Standard (DES) and the Advanced Encryption Standard (AES) are examples of symmetric key algorithms.
There are two types of symmetric key algorithms:
Block ciphers In a block cipher, the actual encryption code works on a fixed-size block of data. Normally, the user's interface to the encrypt/decrypt operation will handle data longer than the block size by repeatedly calling the low-level encryption function. If the length of data is not on a block size boundary, it must be padded.
Stream ciphers Stream ciphers do not work on a block basis, but convert 1 bit (or 1 byte) of data at a time.
2. With a public key (PKA) or asymmetric key algorithm, a pair of keys is used. One of the keys, the private key, is kept secret and not shared with anyone. The other key, the public key, is not secret and can be shared with anyone. When data is encrypted by one of the keys, it can only be decrypted and recovered by using the other key. The two keys are mathematically related, but it is virtually impossible to derive the private key from the public key. The RSA algorithm is an example of a public key algorithm.
Public key algorithms are slower than symmetric key algorithms. Applications typically use public key algorithms to encrypt symmetric keys (for key distribution) and to encrypt hashes (in digital signature generation).
Together, the key and the cryptographic algorithm transform the data. All of the supported algorithms are in the public domain. Therefore it is the key that controls access to the data. You must safeguard the keys to protect the data.
LAB 3 (28 July 2009)
This week I learn about Cryptography Concept. Before that I must know what is Cryptography. Cryptography is the art and science of keeping data secure. Cryptographic services help ensure data privacy, maintain data integrity, authenticate communicating parties, and prevent repudiation (when a party refutes having sent a message).
Basic encryption allows you to store information or to communicate with other parties while preventing non-involved parties from understanding the stored information or understanding the communication. Encryption transforms understandable text (plaintext) into an unintelligible piece of data (ciphertext). Decryption restores the understandable text from the unintelligible data. Both functions involve a mathematical formula (the algorithm) and secret data (the key).
Cryptographic algorithms
There are two types of cryptographic algorithms:
1. With a secret or symmetric key algorithm, the key is a shared secret between two communicating parties. Encryption and decryption both use the same key. The Data Encryption Standard (DES) and the Advanced Encryption Standard (AES) are examples of symmetric key algorithms.
There are two types of symmetric key algorithms:
Block ciphers In a block cipher, the actual encryption code works on a fixed-size block of data. Normally, the user's interface to the encrypt/decrypt operation will handle data longer than the block size by repeatedly calling the low-level encryption function. If the length of data is not on a block size boundary, it must be padded.
Stream ciphers Stream ciphers do not work on a block basis, but convert 1 bit (or 1 byte) of data at a time.
2. With a public key (PKA) or asymmetric key algorithm, a pair of keys is used. One of the keys, the private key, is kept secret and not shared with anyone. The other key, the public key, is not secret and can be shared with anyone. When data is encrypted by one of the keys, it can only be decrypted and recovered by using the other key. The two keys are mathematically related, but it is virtually impossible to derive the private key from the public key. The RSA algorithm is an example of a public key algorithm.
Public key algorithms are slower than symmetric key algorithms. Applications typically use public key algorithms to encrypt symmetric keys (for key distribution) and to encrypt hashes (in digital signature generation).
Together, the key and the cryptographic algorithm transform the data. All of the supported algorithms are in the public domain. Therefore it is the key that controls access to the data. You must safeguard the keys to protect the data.
LAB 3 (28 July 2009)
The topic of this lab is Authentication and Basic Cryptography. End of this section I must know what is Authentication and Cryptography, know to implementing Data encryption. Also know to implementing Local password policy on windows 2003 and to implementing Asymmetric cryptography by using Pretty Good Privacy (PGP).
Authentication is the process of determining whether someone or something is, in fact, who or what it is declared to be. In private and public computer networks (including the Internet), authentication is commonly done through the use of logon passwords.
Authentication is the process of determining whether someone or something is, in fact, who or what it is declared to be. In private and public computer networks (including the Internet), authentication is commonly done through the use of logon passwords.
Cryptography is the art and science of keeping data secure. Cryptographic services help ensure data privacy, maintain data integrity, authenticate communicating parties, and prevent repudiation (when a party refutes having sent a message). Within the context of any application-to-application communication, there are some specific security requirements, including:
• Authentication: The process of proving one's identity. (The primary forms of host-to-host authentication on the Internet today are name-based or address-based, both of which are notoriously weak.)
• Privacy/confidentiality: Ensuring that no one can read the message except the intended receiver.
• Integrity: Assuring the receiver that the received message has not been altered in any way from the original.
• Non-repudiation: A mechanism to prove that the sender really sent this message.
• Authentication: The process of proving one's identity. (The primary forms of host-to-host authentication on the Internet today are name-based or address-based, both of which are notoriously weak.)
• Privacy/confidentiality: Ensuring that no one can read the message except the intended receiver.
• Integrity: Assuring the receiver that the received message has not been altered in any way from the original.
• Non-repudiation: A mechanism to prove that the sender really sent this message.
Encryption is the conversion of data into a form, called a ciphertext, that cannot be easily understood by unauthorized people. Decryption is the process of converting encrypted data back into its original form, so it can be understood. The use of encryption/decryption is as old as the art of communication. In wartime, a cipher, often incorrectly called a code, can be employed to keep the enemy from obtaining the contents of transmissions.
Encryption and Decryption operation.
Encryption and Decryption operation.
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