RSA encryption and decryption
RSA encryption and decryption:
RSA algorithm is very simple, summarized as follows:
To find two primes p and q
Take n = p * q
Take t = (p-1) * (q-1)
Take any of a number e, required to satisfy e
Get d * e% t == 1
This eventually get three numbers: nde
Set message number M (M
Set c = (M ** d)% n to get the encrypted message c
Set m = (c ** e)% n then m == M, c to complete the decryption.
Note: ** said Power of above two equations in the d and e interchangeable.
In symmetric encryption:
nd two numbers constitute a public key, you can tell other people;
ne two numbers constitute the private key, e their own reservations, that no one knows.
Send the information to others using e encryption, as long as people can use d unlock information is to prove that you sent form the signature mechanism.
When someone sends information encrypted using the d, e, so you can only have its decryption.
rsa security is for a large number n, there is no effective method can be decomposed to nd in the case of the known lack of access to e; the same in the case of known ne can not obtain d.
Or, rsa security is for a large number n, there is no effective way to be decomposed into p and q.
<2> Practice
Next we come to a practice and see the actual operation:
To find two prime numbers:
p = 47
q = 59
So
n = p * q = 2773
t = (p-1) * (q-1) = 2668
Take e = 63, satisfy e
C: \ Temp> perl-e "foreach $ i (1 .. 9999) (print ($ i), last if $ i * 63% 2668 == 1)"
847
That is d = 847
Finally we get the key
n = 2773
d = 847
e = 63
Message M = 244 we take a look
Encryption:
c = M ** d% n = 244 ** 847% 2773
Computation of large numbers with perl to count:
C: \ Temp> perl-Mbigint-e "print 244 ** 847% 2773"
465
D on M that is encrypted with access to encrypted information, c = 465
Decryption:
We can use e to the c of the encrypted decrypt, restore, M:
m = c ** e% n = 465 ** 63% 2773:
C: \ Temp> perl-Mbigint-e "print 465 ** 63% 2773"
244
The use of e on c decrypted get m = 244, the M value and equal to the original information.
RSA algorithm is very simple, summarized as follows:
To find two primes p and q
Take n = p * q
Take t = (p-1) * (q-1)
Take any of a number e, required to satisfy e
Get d * e% t == 1
This eventually get three numbers: nde
Set message number M (M
Set c = (M ** d)% n to get the encrypted message c
Set m = (c ** e)% n then m == M, c to complete the decryption.
Note: ** said Power of above two equations in the d and e interchangeable.
In symmetric encryption:
nd two numbers constitute a public key, you can tell other people;
ne two numbers constitute the private key, e their own reservations, that no one knows.
Send the information to others using e encryption, as long as people can use d unlock information is to prove that you sent form the signature mechanism.
When someone sends information encrypted using the d, e, so you can only have its decryption.
rsa security is for a large number n, there is no effective method can be decomposed to nd in the case of the known lack of access to e; the same in the case of known ne can not obtain d.
Or, rsa security is for a large number n, there is no effective way to be decomposed into p and q.
<2> Practice
Next we come to a practice and see the actual operation:
To find two prime numbers:
p = 47
q = 59
So
n = p * q = 2773
t = (p-1) * (q-1) = 2668
Take e = 63, satisfy e
C: \ Temp> perl-e "foreach $ i (1 .. 9999) (print ($ i), last if $ i * 63% 2668 == 1)"
847
That is d = 847
Finally we get the key
n = 2773
d = 847
e = 63
Message M = 244 we take a look
Encryption:
c = M ** d% n = 244 ** 847% 2773
Computation of large numbers with perl to count:
C: \ Temp> perl-Mbigint-e "print 244 ** 847% 2773"
465
D on M that is encrypted with access to encrypted information, c = 465
Decryption:
We can use e to the c of the encrypted decrypt, restore, M:
m = c ** e% n = 465 ** 63% 2773:
C: \ Temp> perl-Mbigint-e "print 465 ** 63% 2773"
244
The use of e on c decrypted get m = 244, the M value and equal to the original information.
The famous cryptographers who proposed RSA Encryption algorithm
The above 3 persons are Famous cryptographers Rivest,Shamir and Adelman Who proposed RSA Encryption Algorithm.Frome Thier Names First letters are Named as RSA for their RSA encryption algorithm.
UML FAQS
Diagram :
A diagram is a graphical presentation of a collection of model elements. This presentation is a projection of those elements of a given model.
Most UML diagrams show model elements as vertices and the relationships among those elements as arcs.
The UML defines nine types of diagrams:
· use case diagram
· class diagram
· object diagram
· activity diagram
· sequence diagram
· statechart diagram
· collaboration diagram
· component diagram
· deployment diagram
Use Case Diagrams
Use case diagrams model the functionality of system using actors and use cases.
Use case diagrams model the functionality of system using actors and use cases.
Class Diagrams
Class diagrams are the backbone of almost every object oriented method, including UML. They describe the static structure of a system.
Class diagrams are the backbone of almost every object oriented method, including UML. They describe the static structure of a system.
Object Diagrams
Object diagrams describe the static structure of a system at a particular time. They can be used to test class diagrams for accuracy.
Object diagrams describe the static structure of a system at a particular time. They can be used to test class diagrams for accuracy.
Activity Diagrams
Activity diagrams illustrate the dynamic nature of a system by modeling the flow of control from activity to activity. An activity represents an operation on some class in the system that results in a change in the state of the system. Typically, activity diagrams are used to model workflow or business processes and internal operation.
Activity diagrams illustrate the dynamic nature of a system by modeling the flow of control from activity to activity. An activity represents an operation on some class in the system that results in a change in the state of the system. Typically, activity diagrams are used to model workflow or business processes and internal operation.
Sequence Diagrams
Sequence diagrams describe interactions among classes in terms of an exchange of messages over time.
Sequence diagrams describe interactions among classes in terms of an exchange of messages over time.
Statechart Diagrams
Statechart diagrams describe the dynamic behavior of a system in response to external stimuli. Statechart diagrams are especially useful in modeling reactive objects whose states are triggered by specific events.
Statechart diagrams describe the dynamic behavior of a system in response to external stimuli. Statechart diagrams are especially useful in modeling reactive objects whose states are triggered by specific events.
Collaboration Diagrams
Collaboration diagrams represent interactions between objects as a series of sequenced messages. Collaboration diagrams describe both the static structure and the dynamic behavior of a system.
Collaboration diagrams represent interactions between objects as a series of sequenced messages. Collaboration diagrams describe both the static structure and the dynamic behavior of a system.
Component Diagrams
Component diagrams describe the organization of physical software components, including source code, run-time (binary) code, and executables.
Component diagrams describe the organization of physical software components, including source code, run-time (binary) code, and executables.
Deployment Diagrams
Deployment diagrams depict the physical resources in a system, including nodes, components, and connections.
Deployment diagrams depict the physical resources in a system, including nodes, components, and connections.
What is Association ?
When classes are connected together conceptually, that connection is called an association.
When one class associates with another, each one usually plays a role within that association. You can show those roles on the diagram by writing them near the line next to the class that plays the role.
Association may be more complex than just one class connected to another. Several classes can connect to one class.
Sometimes an association between two classes has to follow a rule. You indicate that rule by putting a constraint near the association line.
Sometimes an association between two classes has to follow a rule. You indicate that rule by putting a constraint near the association line.
Just like a class, an association can have attributes and operations. In this case we have an association class.
You visualize association class the same way you show a regular class, and you use dotted line to connect it to the association line.
Multiplicity is a special type of association which shows the number of objects from one class that relate with a number of objects in an associated class.
One class can be relate to another in a
•one-to-one
•one-to-many
•one-to-one or more
•one-to-zero or one
•one-to-a bounded interval (one-to-two through twenty)
•one-to-exactly n
•one-to-a set of choices (one-to-five or eight)
The UML uses an asterisk (*) to represent more and to represent many.
Sometimes, a class is in association with itself. This can happen when a class has objects that can play a variety of roles. These associations are called reflexive associations.
NOTE : Inheritance is a kind of Association.
NOTE : Classes that provide no objects are said to be abstract classes. You indicate an abstract class by writing its name in italics.
Visibility
Visibility applies to attributes or operations, and specifies the extent to which other classes can use a given class's attributes or operations.
Three levels of visibility are possible (last symbols are used in UML classes to indicate different levels of visibility):
| Levels | Explanation | Notation |
| Public level | usability extends to other classes | + |
| Protected level | usability is open only to classes that inherit from original class | # |
| Private level | only the original class can use the attribute or operation | - |
What is the difference between Aggregation and Composition ?
Aggregation is represented as a hierarchy with the "whole" class at the top, and the component below. A line joins a whole to a component with an open diamond on the line near the whole.
An aggregation association in the TV Set system
A composite is a strong type of aggregation. Each component in a composite can belong to just one whole. The symbol for a composite is the same as the symbol for an aggregation except the diamond is filled.
A composite association. In this association each component belongs to exactly one whole.
Interfaces and Realizations
An interface is a set of operations that specifies some aspect of a class behaviour, and it's a set of operations a class presents to other classes.
You model an interface the same way you model a class, with the rectangle icon, but interface has no attributes, only operations. Another way is with a small circle joined with line to a class.
An interface is a collection of operations that a class carries out.
To distinguish interfaces from classes, in stereotype construct we put <> or I at the begining of the name of any interface.
The relationship between a class and an interface is called realization. This relationship is modeled as a dashed line with a large open triangle adjoining and pointing to the interface.
Sequence Diagrams :
The sequence diagram consists of objects represented in the usual way - as named rectangles (with the name underlined), messages represented as solid-line arroes, and time represented as a vertical progression.
Objects
The objects are laid out near the top of the diagram from left to right. They're arranged in any order that simplifies the diagram. Extending downforward from each object is a dashed line called the object's lifeline. Along the lifeline is narrow rectangle called an activation. The activation represents an execution of an operation the object carries out. The length of the rectangle signifies the activation's duration. This is shown on next picture.
Representing an object in a sequence diagram
Messages
A message that goes from one object to another goes from one object's lifeline to the other object's lifeline. An object can send a message to itself-that is, from its lifeline back to its own lifeline. This is called recursion. See recursion example.
Following table lists all of possible messages existing in the UML sequence diagrams, with their graphical representations:
Simple | This is a transfer of control from one object to another. |
| ||||||
 Synchronous | If an object sends a synchronous message, it waits for an answer to that message before it proceeds with its business. | | ||||||
  Asynchronous | If an object sends an asynchronous message, it doesn't wait for an answer before it proceeds. | |
Time
The diagram represents time in the vertical direction. Time starts at the top and progresses toward the bottom. A message that's closer to the top occurs earlier in time than a message that's closer to the bottom.
The essential symbol set of the sequence diagram, with the symbols working together.
NOTE : The actor-symbol initiates the sequence, but the stick figure isn't part of the sequence diagram symbol set.
In a sequence diagram, the objects are laid out from left to right across the top. Each object' lifeline is a dashed line extending downward from the object. A solid line with an arrowhead connects one lifeline to another, and represents a message from one object to another. Time starts at the top an proceeds downward. Although an actor typically initiates the sequence, the actor symbol isn't part of the sequence diagram's symbol set.
JAVA FAQS
– 3 Main Roles:
• Model
• Encapsulates application state
• Responds to state queries
• Exposes application
• Notifies Views of changes
» EJB Entity Beans
» Command Beans (Websphere)
• View
• Renders the models
• Requests updates from the Models
• Sends user gestures to the Controller
• Allows the Controller to select the View
» JSPs
» Servlets
» JavaBeans
• Controller
• Defines application behavior
• Maps user actions to Model updates
• Selects View for response
• One for each functionality
Infosys
History
Established in 1981, Infosys is a NASDAQ listed global consulting and IT services company with more than 105,000 employees. From a capital of US$ 250, we have grown to become a US$ 4 billion company with a market capitalization of approximately US$ 27 billion.
In our journey of over 28 years, we have catalyzed some of the major changes that have led to India India India
Read more about the defining moments in Infosys' history.
Milestones
2008
· Infosys crosses revenues of US$ $ 4.18 billion. Employees grow to over 90,000+
· Reports Q4 revenue of US$ 1,142 million
2007
· Infosys crosses revenues of US$ 3 billion. Employees grow to over 70,000+
· Kris Gopalakrishnan, COO, takes over as CEO. Nandan M. Nilekani is appointed Co-Chairman of the Board of Directors
· Opens new subsidiary in Latin America
· Reports Q2 revenue of over US$ 1billion
2006
· Infosys celebrates 25 years. Revenues cross US$ 2 billion. Employees grow to 50,000+
· N. R. Narayana Murthy retires from the services of the company on turning 60. The Board of Directors appoints him as an Additional Director. He continues as Chairman and Chief Mentor of Infosys
2005
· Records the largest international equity offering of US$ 1 billion from India
· Selected to the Global MAKE Hall of Fame
2004
· Revenues reach US$ 1 billion
· Infosys Consulting Inc. is launched
2003
· Establishes subsidiaries in China and Australia
· Expands operations in Pune and China , and sets up a Development Center
2002
· Touches revenues of US$ 500 million
· Nandan M. Nilekani takes over as CEO from N.R. Narayana Murthy, who is appointed Chairman and Chief Mentor
· Opens offices in The Netherlands, Singapore and Switzerland
· Sponsors secondary ADS offering
· Infosys and the Wharton School of the University of Pennsylvania
· Launches Progeon, offering business process outsourcing services
2001
· Touches revenues of US$ 400 million. Opens offices in UAE and Argentina , and a Development Center in Japan
· N. R. Narayana Murthy is rated among Time Magazine/CNN's 25 most influential businessmen in the world
· Infosys is rated as the Best Employer by Business World/Hewitt
2000
· Touches revenues of US$ 200 million
· Opens offices in France and Hong Kong, a global development center in Canada and UK , and three development centers in the US
· Re-launches Banks 2000, the universal banking solution from Infosys, as Finacle™
1999
· Touches revenues of US$ 100 million. Listed on NASDAQ
· Infosys becomes the 21st company in the world to achieve a CMM Level 5 certification
· Opens offices in Germany , Sweden , Belgium , Australia , and two development centers in the US
· Infosys Business Consulting Services is launched
1998
· Starts enterprise solutions (packaged applications) practice
1997
· Opens an office in Toronto , Canada
· Infosys is assessed at CMM Level 4
1996
· The Infosys Foundation is established
1995
· Opens first European office in the UK and Global Development Centers at Toronto
1994
· Moves corporate headquarters to Electronics City , Bangalore Development Center at Fremont
1993
· Introduces Employee Stock Options (ESOP) program
· Acquires ISO 9001/TickIT certification
· Goes public
1987
· Opens first international office in Boston , US
1983
· Relocates corporate headquarters to Bangalore
1981
· Infosys is established by N. R. Narayana Murthy and six engineers in Pune , India
· Signs up its first client, Data Basics Corporation, in New York
N. R. Narayana Murthy
Chairman of the Board and Chief Mentor, Infosys Technologies
N. R. Narayana Murthy is the Founder-Chairman of Infosys Technologies Limited. He founded Infosys in 1981. Under his leadership, Infosys was listed on NASDAQ in 1999.
Mr. Murthy articulated, designed and implemented the Global Delivery Model which has become the foundation for the huge success in IT services outsourcing from India India
He serves on the boards of Unilever, HSBC, Ford Foundation and the UN Foundation. He also serves on the boards of Cornell University , Wharton School , Singapore Management University, Indian School of Business, Hyderabad , Indian institute of Management Technology , Bangalore
The Economist ranked Narayana Murthy among the ten most-admired global business leaders in 2005. He topped the Economic Times list of India