Different Generator Cooling Methods. Generators range from the small portable kinds that people use as backup power for their homes to large industrial units used as the prime power source at remote oil drilling sites. If the bit-stream generator is a key-controlled algorithm the two users only need to share the generating key and then each can produce the keystream. True A problem with the ideal block cipher using a small block size is that it is vulnerable to a statistical analysis of the plaintext. Oct 18, 2016 Primarily there are two types of encryption schemes: Symmetric and Asymmetric(Public Key encryption). Symmetric Encryption schemes like AES, DES use a key of defined bit size. The key is generated during the course of the algorithm by a mathematical function called as PRNGs(Pseudo Random Number Generators).
TopBlend: Here is the first difference. There are 3 differences.javax.crypto
Class KeyGenerator
- public class KeyGenerator
- extends Object
This class provides the functionality of a (symmetric) key generator.
Key generators are constructed using one of the getInstance class methods of this class.
KeyGenerator objects are reusable, i.e., after a key has been generated, the same KeyGenerator object can be re-used to generate further keys.
There are two ways to generate a key: in an algorithm-independent manner, and in an algorithm-specific manner. The only difference between the two is the initialization of the object:
- Algorithm-Independent InitializationAll key generators share the concepts of a keysize and a source of randomness. There is an init method in this KeyGenerator class that takes these two universally shared types of arguments. There is also one that takes just a keysize argument, and uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness (or a system-provided source of randomness if none of the installed providers supply a SecureRandom implementation), and one that takes just a source of randomness.Since no other parameters are specified when you call the above algorithm-independent init methods, it is up to the provider what to do about the algorithm-specific parameters (if any) to be associated with each of the keys.
- Algorithm-Specific InitializationFor situations where a set of algorithm-specific parameters already exists, there are two init methods that have an AlgorithmParameterSpec argument. One also has a SecureRandom argument, while the other uses the SecureRandom implementation of the highest-priority installed provider as the source of randomness (or a system-provided source of randomness if none of the installed providers supply a SecureRandom implementation).
In case the client does not explicitly initialize the KeyGenerator (via a call to an init method), each provider must supply (and document) a default initialization.
- Since:
- 1.4
- See Also:
- SecretKey
Constructor Summary | |
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protected | KeyGenerator(KeyGeneratorSpi keyGenSpi, Provider provider, String algorithm) Creates a KeyGenerator object. |
Method Summary | |
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SecretKey | generateKey() Generates a secret key. |
String | getAlgorithm() Returns the algorithm name of this KeyGenerator object. |
static KeyGenerator | getInstance(String algorithm) Generates a KeyGenerator object for the specified algorithm. |
static KeyGenerator | getInstance(String algorithm, Provider provider) Generates a KeyGenerator object for the specified key algorithm from the specified provider. |
static KeyGenerator | getInstance(String algorithm, String provider) Generates a KeyGenerator object for the specified key algorithm from the specified provider. |
Provider | getProvider() Returns the provider of this KeyGenerator object. |
void | init(AlgorithmParameterSpec params) Initializes this key generator with the specified parameter set. |
void | init(AlgorithmParameterSpec params, SecureRandom random) Initializes this key generator with the specified parameter set and a user-provided source of randomness. |
void | init(int keysize) Initializes this key generator for a certain keysize. |
void | init(int keysize, SecureRandom random) Initializes this key generator for a certain keysize, using a user-provided source of randomness. |
void | init(SecureRandom random) Initializes this key generator. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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KeyGenerator
- Creates a KeyGenerator object.
- Parameters:
- keyGenSpi - the delegate
- provider - the provider
- algorithm - the algorithm
Method Detail |
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getAlgorithm
Returns the algorithm name of this KeyGenerator object.This is the same name that was specified in one of the getInstance calls that created this KeyGenerator object.
- Returns:
- the algorithm name of this KeyGenerator object.
getInstance
- Generates a KeyGenerator object for the specified algorithm. If the default provider package provides an implementation of the requested key generator, an instance of KeyGenerator containing that implementation is returned. If the requested key generator is not available in the default provider package, other provider packages are searched.
- Parameters:
- algorithm - the standard name of the requested key algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
- Returns:
- the new KeyGenerator object
- Throws:
- NullPointerException- if the specified algorithm is null.
- NoSuchAlgorithmException - if a key generator for the specified algorithm is not available in the default provider package or any of the other provider packages that were searched.
getInstance
- Generates a KeyGenerator object for the specified key algorithm from the specified provider.
- Parameters:
- algorithm - the standard name of the requested key algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
- provider - the name of the provider
- Returns:
- the new KeyGenerator object
- Throws:
- NullPointerException- if the specified algorithm is null.
- NoSuchAlgorithmException - if a key generator for the specified algorithm is not available from the specified provider.
- NoSuchProviderException - if the specified provider has not been configured.
- IllegalArgumentException - if the provider is null.
getInstance
- Generates a KeyGenerator object for the specified key algorithm from the specified provider. Note: the provider doesn't have to be registered.
- Parameters:
- algorithm - the standard name of the requested key algorithm. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard algorithm names.
- provider - the provider
- Returns:
- the new KeyGenerator object
- Throws:
- NullPointerException- if the specified algorithm is null.
- NoSuchAlgorithmException - if a key generator for the specified algorithm is not available from the specified provider.
- IllegalArgumentException - if the provider is null.
getProvider
- Returns the provider of this KeyGenerator object.
- Returns:
- the provider of this KeyGenerator object
init
- Initializes this key generator.
- Parameters:
- random - the source of randomness for this generator
init
![Generator Generator](/uploads/1/2/5/8/125869899/626085825.png)
If this key generator requires any random bytes, it will get them using the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.)
- Parameters:
- params - the key generation parameters
- Throws:
- InvalidAlgorithmParameterException - if the given parameters are inappropriate for this key generator
init
- Initializes this key generator with the specified parameter set and a user-provided source of randomness.
- Parameters:
- params - the key generation parameters
- random - the source of randomness for this key generator
- Throws:
- InvalidAlgorithmParameterException - if params is inappropriate for this key generator
init
Initializes this key generator for a certain keysize. If this key generator requires any random bytes, it will get them using the SecureRandom implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.)
- Parameters:
- keysize - the keysize. This is an algorithm-specific metric, specified in number of bits.
- Throws:
- InvalidParameterException - if the keysize is wrong or not supported.
init
What Are Two Types Of Key Generation Techniques
- Initializes this key generator for a certain keysize, using a user-provided source of randomness.
- Parameters:
- keysize - the keysize. This is an algorithm-specific metric, specified in number of bits.
- random - the source of randomness for this key generator
- Throws:
- InvalidParameterException - if the keysize is wrong or not supported.
![What Are Two Types Of Key Generator Techniques What Are Two Types Of Key Generator Techniques](/uploads/1/2/5/8/125869899/129373698.jpg)
generateKey
What Are Two Types Of Key Generator Techniques Pdf
- Generates a secret key.
- Returns:
- the new key