Information has always been a powerful thing to possess. People can influence a situation by knowing certain aspects that were supposed to be concealed. Cryptography is known as an art, understood and used by Caesar in the ancient times, Leonardo da Vinci in the epoch of Renaissance, and political leaders in the period of war. Cryptography means “hidden writing”, and it is a system used in order to protect information. It is now an academic discipline that has proved to be useful in the era of internet technologies. The paper discusses the cryptography and cryptographic services that are available for using by government, companies, and separate individuals as well.
Secrecy has been always important, but due to the event of the First World War, when information could save lives and change the course of the things, new devices have appeared. Special people have worked on the inventing of an unbreakable machine that is impossible to decipher. It has been a simple cipher wheel that Thomas Jefferson has improved; an “enigma” created by Arthur Scherbius later, and “for many years, this sort of cryptography was the exclusive domain of the military” (Scheier, 1996, p.15). It is the internet that gives now the best opportunities for cryptography to develop.
The idea of cryptography is to provide the security of information by turning it into a cipher. Cryptography is an important system of confidentiality that disguises data in such a way that it becomes inaccessible for an unauthorized person. Information for concealing is known as a plaintext, and the procedure of disguising is called encryption. The opposite of the encryption process is decryption. Decryption consists in changing hidden information (cryptogram) into the form applicable for reading. A set of complex rules used for encryption of messages is the encryption algorithm. If an encrypted writing falls into the hands of a wrong person, then it should be incomprehensible information, because only a recipient and a sender have a key. An encryption key is an appropriate detail that helps to obtain the message. Without a key it is impossible to select an algorithm.
The processes of encryption and decryption can by illustrated. It is possible to give a formula, where a plaintext stands for P, or M (message) and defines any sort of information that has to be encrypted. Other components are: a cipher text – C; encryption – E. According to the formula that is given by Bruce Schneier, “The encryption function E, operates on M to produce C. Or, in mathematical notation: E(M) = C. In the reverse process, the decryption function D operates on C to produce M: D(C) = M. Since the whole point of encrypting and then decrypting a message is to recover the original plaintext, the following identity must hold true: D(E(M)) = M” (Schneier, 1996, p.147).
Particular algorisms that make a cryptographic operation possible to provide are called cryptographic services, and they are:
1. Digital signature
2. Message digest
3. Key conversion service
Digital signature is a contemporary and improved version of a traditional signature written on a piece of paper with ink. It is a reliable way to protect information and ensure its safety. A digital signature is used to identify an authentic signer of the data. Due to the objective of digital signatures it may require the same mechanism of work as traditional signatures ensure. This means that digital signatures can also insure inviolability and strike of the possibility of changing facts or details of the message. The data cannot be altered without noticing, because replacements become visible immediately.
For creating a digital signature, a person has to make a message digest of the information. A singer uses a key (only he and a receiver knows) to encrypt the digest. The algorism is used with a certificate that verifies the signature. The key is a part of this cryptographic service. To check whether the information has not been altered, or not, the receiver has to apply the algorithm and create message digests. The key helps to decrypt the signature digest. In case of identification of the two digests, the security of the message is guaranteed. The certification is also checked, and it ensures that a person who has signed a message is the same person who has written it.
A digital signature is a powerful cryptographic service. It plays a great role in keeping information safe. Digital signatures are encouraged to be put on different application by companies. It is soon that this way of checking the validity of the data will be required everywhere, and not only for software distribution, or financial transactions. The legal significance of digital signatures establishes the security of information and provides access to reliable sources. Secure communication is a priority of cryptography. A message digest is a means of preserving the confidentiality. Message digests and digital signatures are used to make certain that information has not been changed.
A cryptographic message digest is impossible to transform into the plaintext, and cannot be created from any other input. A fact that the transformation of the data is not reversible turns a message digest into a perfectly secure service. A message digest has been invented by Peter Gutmann, but it is not patented and can be used for free by anyone (Schneier, 1996).
The software world uses message digests to provide accuracy while transferring files. Mathematical functions produce a different message digest for each unique document. Messages digests are commonly used for protecting electronic files.
A key conversion service consists of two basic concepts – the public key and the private key. The idea of this design is that it is necessary to have two keys for any operation with information. Public key is for encryption of the data. It is different from the private key that is used for decryption. Even though considerable efforts may be made to decipher information, the decryption key cannot be deduced from the inscription one. It is called a public key, because access to it can be given to a complete stranger. Any person is able to use the public key to encrypt the message, but only he, who has the private key, can get the meaning of the message. According to Bruce Scheier, “Putting mail in the mailbox is analogous to encrypting with the public key; anyone can do it. Just open the slot and drop it in. Getting mail out of a mailbox is analogous to decrypting with the private key” (Schneier, 1996, p.58).
The key conversion service represents advance technology cryptography uses with great success. It shows the progress that has been made since the era of the internet came. To have the keys at disposal means that they still have to be protected. In case of losing the private or public key, it can be restored. This ascertains in the effectiveness of the key service in preserving information.
The three cryptographic services have been described: a digital signature, a message digest, and a key conversion service. The services are legal tools that can help to protect the privacy. These three means of decoding have developed from the old devices. The importance of information has never been underestimated that is the reason that an art of encryption is and decryption is an academic discipline now. The flow of data is a serious problem that has to be properly controlled and kept safe from unauthorized users.
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