One-way encryption:Information is encrypted once and cannot be decrypted
Asymmetric encryption:One key is used to encrypt a message and another key used to decrypt it
Symmetric encryption:A single key is used to encrypt and decrypt the message
Algorithm: A computable set of steps used to achieve a desired result
Ciphertext:Text that has been encrypted by some encryption system
Question: Which is the term for a website that uses encryption techniques to protect its data? Answer: A secure website that implements SSL.
Basic Vocabulary of Encryption and Decryption
plaintext: This is what you want to encrypt
ciphertext: The encrypted output enciphering or encryption: The process by which plaintext is converted into ciphertext
encryption algorithm: The sequence of data processing steps that go into transforming plaintext into ciphertext.
Various parameters used by an encryption algorithm are derived from a secret key. In cryptography for commercial and other civilian applications, the encryption and decryption algorithms are made public.
secret key: A secret key is used to set some or all of the various parameters used by the encryption algorithm. The important thing to note is that, in classical cryptography, the same secret key is used for encryption and decryption.
It is for this reason that classical cryptography is also referred to as symmetric key cryptography. On the other hand, in the more modern cryptographic algorithms, the encryption and decryption keys are not only different, but also one of them is placed in the public domain.
Such algorithms are commonly referred to as asymmetric key cryptography, public key cryptography, etc.
deciphering or decryption: Recovering plaintext from ciphertext
decryption algorithm: The sequence of data processing steps that go into transforming ciphertext back into plaintext.
In classical cryptography, the various parameters used by a decryption algorithm are derived from the same secret key that was used in the encryption algorithm.
cryptography: The many schemes available today for encryption and decryption
cryptographic system: Any single scheme for encryption and decryption
cipher: A cipher means the same thing as a cryptographic system
block cipher: A block cipher processes a block of input data at a time and produces a ciphertext block of the same size.
stream cipher: A stream cipher encrypts data on the fly, usually one byte at at time.
cryptanalysis: Means "breaking the code". Cryptanalysis relies on a knowledge of the encryption algorithm (that for civilian applications should be in the public domain) and some knowledge of the possible structure of the plaintext (such as the structure of a typical inter-bank financial transaction) for a partial or full reconstruction of the plaintext from ciphertext.
Additionally, the goal is to also infer the key for decryption of future messages.
key space: The total number of all possible keys that can be used n a cryptographic system. For example, DES uses a 56-bit key.So the key space is of size 256, which is approximately the same as 7.2 X 10^{16}.