Java Generate Keys Based On Set Of Numbers
In order to be able to create a digital signature, you need a private key. (Its corresponding public key will be needed in order to verify the authenticity of the signature.)
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The easiest way to pick unique random numbers is to put the range of numbers into a collection called an ArrayList. If you've not come across an ArrayList before, it's a way of storing a set of elements that don't have a fixed number. The elements are objects that can be added to or removed from the list. Random alpha numeric string of fixed size. In this section, you will learn to generate fixed size alpha numeric string using core Java code. In this section, you will learn to generate fixed size alpha numeric string using core Java code. Hi, I am new to Java i have a assignment and that is i need to generate 1,00,00,000 (one crore ) random numbers and which should be seed based random Generating Unique Random Numbers in JAVA (Beginning Java forum at Coderanch). Java Program for Sum the digits of a given number Extract all integers from the given string in Java Introduction to Project Lombok in Java and How to get started?
In some cases the key pair (private key and corresponding public key) are already available in files. In that case the program can import and use the private key for signing, as shown in Weaknesses and Alternatives.
In other cases the program needs to generate the key pair. A key pair is generated by using the KeyPairGenerator class.
In this example you will generate a public/private key pair for the Digital Signature Algorithm (DSA). You will generate keys with a 1024-bit length.
Generating a key pair requires several steps:
Create a Key Pair Generator
The first step is to get a key-pair generator object for generating keys for the DSA signature algorithm. Fl studio registration key generator.
As with all engine classes, the way to get a KeyPairGenerator object for a particular type of algorithm is to call the getInstance static factory method on the KeyPairGenerator class. This method has two forms, both of which hava a String algorithm first argument; one form also has a String provider second argument.
A caller may thus optionally specify the name of a provider, which will guarantee that the implementation of the algorithm requested is from the named provider. The sample code of this lesson always specifies the default SUN provider built into the JDK.
Put the following statement after the
line in the file created in the previous step, Prepare Initial Program Structure:
Initialize the Key Pair Generator
The next step is to initialize the key pair generator. All key pair generators share the concepts of a keysize and a source of randomness. The KeyPairGenerator class has an initialize method that takes these two types of arguments.
The keysize for a DSA key generator is the key length (in bits), which you will set to 1024.
The source of randomness must be an instance of the SecureRandom class that provides a cryptographically strong random number generator (RNG). For more information about SecureRandom, see the SecureRandom API Specification and the Java Cryptography Architecture Reference Guide .
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The following example requests an instance of SecureRandom that uses the SHA1PRNG algorithm, as provided by the built-in SUN provider. The example then passes this SecureRandom instance to the key-pair generator initialization method.
Some situations require strong random values, such as when creating high-value and long-lived secrets like RSA public and private keys. To help guide applications in selecting a suitable strong SecureRandom implementation, starting from JDK 8 Java distributions include a list of known strong SecureRandom implementations in the securerandom.strongAlgorithms property of the java.security.Security class. When you are creating such data, you should consider using SecureRandom.getInstanceStrong(), as it obtains an instance of the known strong algorithms.
Generate the Pair of Keys
The final step is to generate the key pair and to store the keys in PrivateKey and PublicKey objects.
I want to create Unique Id(s) and as far as requirement is concerned , java program should create every time a unique number. Could some body help me to provide parameters which could be used to create Unique numbers.
Thanks
Vikas
The Javadoc of UID suggests how to generate a globally unique ID:
'An independently generated UID instance is unique over time with respect to the host it is generated on as long as the host requires more than one millisecond to reboot and its system clock is never set backward. A globally unique identifier can be constructed by pairing a UID instance with a unique host identifier, such as an IP address.'
A better choice would be the class java.util.UUID, which does generate universally unique identifiers.
[ April 13, 2007: Message edited by: Jesper Young ]
Java Generate Keys Based On Set Of Numbers Free
Originally posted by Paul Sturrock:
Will a UID do?
Actually same code has to be used on multiple JVMs . So i believe UID wont work .Because these Unique id(s)will be persisted in same storage. Moreover approx 10,000 id(s) need to be created from each box(JVM).
Thanks
Vikas
It will only work with jdk 1.5.
Remko (My website)
SCJP 1.5, SCWCD 1.4, SCDJWS 1.4, SCBCD 1.5, ITIL(Manager), Prince2(Practitioner), Reading/ gaining experience for SCEA,
Issue with GUID is , it creates number with approx 32 digits .
I have to take into consideration max Length as 10 and if i try to manipulate the lenght of GUID generated number , i will loose uniqueness
Originally posted by Remko Strating:
You could create an uniqueId by using the nano time
It will only work with jdk 1.5.
Originally posted by Rahul Bhattacharjee:
UID is from SE 6.0.
Actually, it's been around since 1.1. UUID is new since 1.5.
I used a compound key technique from a Scott Ambler article years ago. To make unique keys across a cluster we go to the database for a DB2 sequence number for part 1. Then we increment an integer from 0 to 999 (or whatever number of digits you like) for part 2. When part2 maxes out, we go back to the database. So we go to the database once for every 1000 keys. The db sequence number is 10 digits and we format the compound as 00000-00000-000 for human consumption. If and when the db approaches max int we can change the format to 000-00000-00000 or use dots or something.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
Originally posted by Joanne Neal:
Actually, it's been around since 1.1. UUID is new since 1.5.
How can you say this.Javadoc marks the version as 1.6
Java Generate Keys Based On Set Of Numbers 1
posted 13 years agojava.rmi.server.UID is since JDK 1.1
java.util.UUID is since Java 1.5
Rahul Bhattacharjee
LinkedIn - Blog
Originally posted by Rahul Bhattacharjee:
But if you want to use this in lower versions then might consider using Random()
That is dangerous advice: randomness is *very* different from uniqueness. Very bad things can happen when you confuse the two.
[to create randomness you might want to add new Object().hashcode() in the constructor of Random()]
That's not necessary at all. The no arg constructor already uses the current system time to create a seed. The trick is to only create one Random object and reuse it - don't create several ones in fast succession.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
I think there is a thin line differentiating between randomness and uniqueness.Could you please help me understand this.
My understanding is that when a unique number generator generates a number and delivers it to the caller , it doesn't remember / cache the number.So when it generates the next unique number then without comparing with the previously generated values how can the program say that its not been generated before.So it gives the same effect as random generator.
But I do not think that there is any harm in specifying a seed to the constructor of Random() , though absolutely not necessary.
Originally posted by Rahul Bhattacharjee:
My understanding is that when a unique number generator generates a number and delivers it to the caller , it doesn't remember / cache the number.So when it generates the next unique number then without comparing with the previously generated values how can the program say that its not been generated before.
The whole point of a unique number generator is that it has to have some way of knowing with a high degree of certainty that the number it has generated is unique.
How this is done depends on the scope within which the number has to be unique.
So, if the number only has to be unique for the lifetime of a single running program, then caching each number in memory as it is generated would be one way of doing this.
If the number had to be unique for every program running on a computer for the lifetime of the computer (even if it is switched off), then you would need some sort of permanent store on that computer to hold every number ever generated.
If you want a universally unique number (which is what UUID gives you) then you would want some way of generating a number that you know to be unique without checking it against a store of numbers. Some possible ways of doing this are descibed here.
Originally posted by Rahul Bhattacharjee:
I think there is a thin line differentiating between randomness and uniqueness.Could you please help me understand this.
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There is no such line. They are separate concepts.If I want to generate unique IDs for a set of things, I can assign numbers 1, 2, 3, and so on. There is no randomness involved at all in this case.
If I toss a coin, I will randomly get heads or tails. Suppose my first toss is a head. If there were any uniqueness involved, then my second toss would be a tail. But in fact there is randomness involved, and my second toss will be randomly a head or a tail.
Is it a shared database (i.e. all the VMs write to the same DB)?
How tight are the performance constraints?
Why 10 chars ? I've worked on a project that generates globally unique IDs on multiple, independent boxes but we use 56 to 64 characters (depending on the representation) and knowing a bit about how it works I don't believe we could use fewer.
Possible solutions:
1.) Use a DB to generate the unique IDs (i.e. a sequence)
2.) Use DB to generate a sequence but have each VM grab some large block in one operation.
3.) Each VM generates its own sequence, prepended with a unique prefix.
There are probably some more esoteric solutions but these are the common things I've seen.
Originally posted by Paul Clapham:
There is no such line. They are separate concepts.
Thanks Paul for the explanation.
Java Generate Keys Based On Set Of Numbers 2017
Say , I have a system which sits in middle of an legacy system and clents.Any application/client which needs to communicate with the legacy application has to go through the middle system.Middle systems except xml's and gives xml replies.The xml requests have a ID field which has to be unique.Many enternal systems can request the middle system.So for this senario what would be the best idea for generating an ID and under stressed conditions the middle system may receive many reuqests symultaneously from many external systems.
Would UUID be the right approach for generating ID's for this senario.
You could have all the clients participate in the compound key scheme I mentioned before, but it can be a nasty Single Point Of Failure. Where I used it, if the database can't vend sequence numbers, we're probably out of business anyhow. I suppose your 'service in the middle' could vend sequence numbers with the same understanding - if it's not available for keys it's not available for service either.
Any chance to change the whole design so the middle tier generates the keys while processing the request and returns them? I know in my case it wasn't practical - the clients had to know the key before sending the request.
Java Generate Keys Based On Set Of Numbers 1
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi