| As new techniques and technologies are being | | | | simply maps plaintext of any length into cipher text |
| introduced with the passage of time, it has become | | | | of a fixed length. This technique is widely used for |
| more important for the companies to adapt new | | | | primitive security checks for digital signatures, |
| techniques to have backup storage for the data. | | | | message integrity, or for password verification. |
| Therefore, the data storage medium must have fast | | | | Cryptographic hash functions are used to prove |
| data recovery ands storage speed. The data storage | | | | message integrity and create digital certificates. |
| medium must be faster and reliable in order to | | | | The flaws in this system include the fact that there |
| compete in the market. | | | | is no usage key, and it is impossible to recover the |
| For the purpose of backup storage, the magnetic | | | | original plaintext. Typical implementations include SHA1 |
| tape is considered as one of the most rigid, reliable, | | | | and MD5. |
| efficient and robust medium. The ultrium LTO (Linear | | | | The hash technique takes a large string of data and |
| Tape Open) tape offers its users the best solutions | | | | converts it mathematically into a fixed-length string. |
| to solve the backup storage issues. It has the | | | | In Hash functions you cannot recreate the original |
| capacity to store and retrieve high volumes of data | | | | data from the hash. However, they are unique and |
| at a high speed. | | | | provide a form of digital fingerprint for a message or |
| All the cryptosystems are based on the | | | | data string. The Message Digest technique is also |
| cryptographic algorithm techniques. The cryptographic | | | | used for checking passwords. The hashes of the |
| algorithm techniques are described below: | | | | passwords are kept in a file. When a username and |
| The secret key encryption | | | | password is entered, the result is compared with the |
| The Secret Key encryption is also known as | | | | version on file. The basic requirements of a hash |
| symmetric encryption. This Secret Key encryption | | | | function H(x) are: |
| technique uses one key for encryption and | | | | The length of input is any. |
| decryption as well. The secret key is subdivided into | | | | There is fixed length of the output. |
| two more classes that are the stream ciphers and | | | | To compute H(x) from x is relatively easy. |
| block ciphers. | | | | The computation of x given H(x) is not possible. This |
| The block ciphers operate on discreet blocks of data, | | | | means that H(x) is one way |
| while on the other hand the stream ciphers encrypt | | | | For different x, the same hash is never repeated. |
| character by providing a continuous stream of | | | | Therefore, the H(x) is collision free |
| encrypted data. The need of high-performance | | | | The asymmetric encryption or Public key encryption |
| applications is supported by the secret key. | | | | This public key technique has one public and one |
| Symmetric encryption is best suited for large | | | | private key as a pair of keys. |
| amounts of fast moving data, usually encrypted in | | | | The public key may be widely distributed and on the |
| blocks. DES (Defense Encryption Standard), triple | | | | other hand, private key is kept secret. This pair of |
| DES, AES (Advanced Encryption Standard) and | | | | keys is related mathematically, but the private key |
| Blowfish are typical examples of Symmetric | | | | cannot be practically derived from the public key. A |
| encryption algorithms. | | | | message which has been encrypted with the public |
| The Hash technique of encryption | | | | key can only be decrypted with the corresponding |
| The hash technique is also known as a Message | | | | private key. |
| Digest and one-way hashes. The Message Digest | | | | |