Application Data Protection Techniques - Secure Java: For Web Application Development - page 159

◾

Modes of encryption

◾ One-way hash functions

◾

MAC and HMAC

8.1.2.1 Encryption and Decryption

Encryption is a process by which readable data called plaintext (also known as cleartext) is ren-
dered as undecipherable data, called ciphertext . he process of encryption ensures that the data
cannot be read and processed until it is decrypted. he plaintext is passed through an encryption
system and consequently is rendered undecipherable. Decryption is a process by which the same
un-understandable ciphertext is passed through an encryption system and is rendered readable
and comprehendible; that is, plaintext.
he process of encryption involves three important elements, namely, the plaintext string/
message, the encryption algorithm, and the key. he plaintext message is processed by the
encryption algorithm, in conjunction with a key to be converted into ciphertext. Let us under-
stand the concept of encryption and decryption with the help of an example. For instance,
there is a safe containing jewelry, which requires a combination to open. A person who wants
to remove the jewelry from the safe would know the combination to open the safe. Once the
correct combination has been entered, the safe may be opened and the jewelry removed. he
jewelry is analogous to plaintext, which is kept inside the safe and locked with the combination.
he safe is the encryption algorithm or the system that encrypts the plaintext and the combi-
nation is the key. he user with knowledge of the combination can enter the combination and
remove the jewelry from the safe.
Encryption is also referred to as encipherment and decryption as decipherment . his was done
because some cultures ind it ofensive to use the word encryption , as it refers to burying the dead
in a tomb. he process of encryption and decryption is highlighted in Figure 8.1.

Ciphertext

Plaintext

“Secure Java for Web
Application
Development”

Encryption Algorithm-
Encryption Process

“_b64K4hutQ3VIWs8UbtM
WQFAJjQh4DYyznVo7HcjI
ndXITQEE2ocapklkCVpMd
HI 8um4_64b”

Ciphertext

Plaintext

“_b64K4hutQ3VIWs8U
btMWQFAJjQh4DYyzn
Vo7HcjIndXITQEE2oca
pklkCVpMd HI
8um4_64b”

Encryption Algorithm-
Decryption Process

“Secure Java for Web
Application
Development”

Figure 8.1 the process of encryption and decryption.