Quantum Computing – The Next Tech Revolution Technology has evolved rapidly over the last few decades—from bulky mainframe computers to powerful smartphones in our pockets. Yet, despite these advances, traditional computers are approaching their physical limits. This is where quantum computing enters the scene, promising to revolutionize the way we process information and solve complex problems. What Is Quantum Computing? Quantum computing is a new paradigm of computing that uses the principles of quantum mechanics, a branch of physics that explains how matter and energy behave at the smallest scales. Unlike classical computers, which use bits that represent either 0 or 1, quantum computers use qubits. Qubits can exist in multiple states simultaneously, thanks to a property called superposition. Additionally, qubits can be interconnected through entanglement, allowing them to share information instantaneously. These unique properties give quantum computers immense computational power....
Protection
* Files must be kept safe for accuracy (against accidental damage ), and protection ( against deliberate malicious access.) The former is usually controlled with backup copies. This section discusses the latter.
* One basic protection method is to remove all access to a file. However this makes the file not usable, so some sort of controlled access must be organized.
Types of Access
The following low-level operations are often controlled:
• Read - See the contents of the file
• Write - Edit the contents of the file.
• Execute - Load the file onto the CPU and follow the instructions consists.
• Append - Add to the end of an available file.
• Delete - delete a file from the system.
• List -View the name and different attributes of files on the system.
Higher-level operations, such as duplicate, can normally be performed through combinations of the above.
Access Control
* One method is to have hard Access Control Lists, ACL, which specify exactly what access is allowed or denied for specific users or groups.
• The AFS uses this system for distributed process.
• Control is very finely adjustable, but may be hard particularly when the
specific users involved are unknown. ( AFS permits some wild cards, so for example all users on a certain remote system may be trusted, or a given username may be trusted when accessing from any remote system. )
* UNIX uses a set of 9 process control bits, in three groups of three. These correspond to R, W, and X allows for each of the Owner, Group, and Others. ( See "man chmod" for full details. ) The RWX bits control the following privileges for regular files and directories:
* Extra there are some special bits that can also be applied:
• The set user ID ( SUID ) bit and/or the set group ID ( SGID ) bits applied to executable files temporarily change the identity of whoever runs the program to
match that of the owner / group of the implementable program. This allows users running particular programs to have access to files ( while running that program ) to which they would normally be unable to access. Setting of these two bits is usually constricted to root, and must be done with caution, as it introduces a
potential security leak.
• The sticky bit on a directory edits write permission, allowing users to only
delete files for which they are the owner. This permits everyone to create files in
/tmp, for example, but to only remove files which they have created, and not anyone else's.
• The SUID, SGID, and sticky bits are implies with an S, S, and T in the positions for execute permission for the user, group, and others, respectively. If the letter is lower case, ( s, s, t ), then the corresponding execute aquisition is not also given. If it is upper case, ( S, S, T ), then the corresponding execute aquisition IS given.
• The numeric form of chmod is required to set these advanced bits.
* Windows alters files access through a simple GUI:
Other Protection Approaches and Issues
* Some systems can apply passwords, either to individual files, or to particular sub-directories, or to the whole system. There is a trade-off between the number of passwords that must be maintained ( and remembered by the users ) and the amount of information that is endangered to a lost or forgotten password.
* Older systems which did not originally have multi-user file access permissions (DOS and older versions of Mac ) must now be furnished if they are to share files on a network.
* Access to a file requires aquire to all the files along its path as well. In a cyclic directory structure, users may have different acquire to the same file retrieved through different paths.
* Sometimes just the knowledge of the existent of a file of a certain name is a private concern. Hence the difference between the R and X bits on UNIX directories.