Section 4 - Exchanging Data Flashcards
What is lossy compression?
Lossy compressions works by removing non-essential information. It results in a loss of quality of the file but also a much smaller file size.
What is lossless compression?
Lossless compression work by recording patterns in data rather than the actual data. Using these patters and a set of instructions on how to use them, the computer can reverse the procedure and reassemble an image, sound or text file with exact accuracy and no data is lost.
What is Run Length Encoding (RLE)
Run Length Encoding exploits the number of times something appears, rather than recording every pixel in a sequence, it records the value and the number of times it appears.
What is dictionary based compression?
Dictionary based compression algorithms search through the text to find suitable entries in its own dictionary (or it may use a knows dictionary) and translates the message accordingly.
What is encryption?
Encryption is the transformation of data from one form to another to prevent an unauthorized third party from being able to understand it. The original data or message is known as plaintext. The encrypted data is known as ciphertext. The encryption method or algorithm is known as the cipher, and the secret information to lock or unlock the message is known as the key.
What is symmetric key? (Private key)
Symmetric encryption, also known as private key encryption, uses the same key to encrypt and decrypt data. This means that the key must also be transferred to the same destination as the ciphertext, which causes obvious security problems. The key can be intercepted as easily as the ciphertext message to decrypt the data.
What is an asymmetric key? (Public key)
Asymmetric encryption uses two separate keys, one known as the public key, made public so that others wishing to send you data can use this to encrypt the data. This public key cannot decrypt data. Another private key is known only by you and can be used to decrypt the data. It is virtually impossible to deduce the private key from the public key, it is possible that a message could be encrypted using your own public key and sent to you by a malicious third party impersonating a trusted individual.
What is hashing?
Hashing functions provide a mapping between an arbitrary length input and a usually fixed length or smaller output. Unlike the encryption techniques described above, it is one-way; you cannot get back to the original. This is useful for strong encrypted PINs and passwords so that they cannot be read by a hacker. To verify a user’s password, the software applies the hash function to the user input and compares it with the one stored.
What is a hash total?
A hash total is a mathematical value calculated from unencrypted message data. This value is also referred to as a checksum or digest. This process is irreversible and impossible to crack other than by trying all of the possible inputs until a match is found. Since the hash total is generated.
What is a digital signature?
A digital signature or hash value is the equivalent of a handwritten signature or security stamp. The sender of the message uses their own private key to encrypt the hash total. The encrypted total becomes the digital signature since only the holder of the private key could have encrypted it. Digital signatures can be used with any kind of messages regardless of whether encryption has also been used.
What are digital certificates?
Digital certificates are issued by official certificate authorities, such as Symantec or Verisign.
