PBEKeySpec (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档
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Java™ Platform Standard Ed. 6 |
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javax.crypto.spec
Class PBEKeySpec
java.lang.Objectjavax.crypto.spec.PBEKeySpec
- All Implemented Interfaces:
- KeySpec
A user-chosen password that can be used with password-based encryption (PBE).
The password can be viewed as some kind of raw key material, from which the encryption mechanism that uses it derives a cryptographic key.
Different PBE mechanisms may consume different bits of each password character. For example, the PBE mechanism defined in PKCS #5 looks at only the low order 8 bits of each character, whereas PKCS #12 looks at all 16 bits of each character.
You convert the password characters to a PBE key by creating an instance of the appropriate secret-key factory. For example, a secret-key factory for PKCS #5 will construct a PBE key from only the low order 8 bits of each password character, whereas a secret-key factory for PKCS #12 will take all 16 bits of each character.
Also note that this class stores passwords as char arrays instead of
String objects (which would seem more logical), because the
String class is immutable and there is no way to overwrite its
internal value when the password stored in it is no longer needed. Hence,
this class requests the password as a char array, so it can be overwritten
when done.
- Since:
- 1.4
- See Also:
SecretKeyFactory,PBEParameterSpec
| Constructor Summary | |
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PBEKeySpec(char[] password)
Constructor that takes a password. |
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PBEKeySpec(char[] password,
byte[] salt,
int iterationCount)
Constructor that takes a password, salt, iteration count for generating PBEKey of fixed-key-size PBE ciphers. |
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PBEKeySpec(char[] password,
byte[] salt,
int iterationCount,
int keyLength)
Constructor that takes a password, salt, iteration count, and to-be-derived key length for generating PBEKey of variable-key-size PBE ciphers. |
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| Method Summary | |
|---|---|
void |
clearPassword()
Clears the internal copy of the password. |
int |
getIterationCount()
Returns the iteration count or 0 if not specified. |
int |
getKeyLength()
Returns the to-be-derived key length or 0 if not specified. |
char[] |
getPassword()
Returns a copy of the password. |
byte[] |
getSalt()
Returns a copy of the salt or null if not specified. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
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PBEKeySpec
public PBEKeySpec(char[] password)
- Constructor that takes a password. An empty char[] is used if
null is specified.
Note:
passwordis cloned before it is stored in the newPBEKeySpecobject.- Parameters:
password- the password.
PBEKeySpec
public PBEKeySpec(char[] password,
byte[] salt,
int iterationCount,
int keyLength)
- Constructor that takes a password, salt, iteration count, and
to-be-derived key length for generating PBEKey of variable-key-size
PBE ciphers. An empty char[] is used if null is specified for
password.Note: the
passwordandsaltare cloned before they are stored in the newPBEKeySpecobject.- Parameters:
password- the password.salt- the salt.iterationCount- the iteration count.keyLength- the to-be-derived key length.- Throws:
NullPointerException- ifsaltis null.IllegalArgumentException- ifsaltis empty, i.e. 0-length,iterationCountorkeyLengthis not positive.
PBEKeySpec
public PBEKeySpec(char[] password,
byte[] salt,
int iterationCount)
- Constructor that takes a password, salt, iteration count for
generating PBEKey of fixed-key-size PBE ciphers. An empty
char[] is used if null is specified for
password.Note: the
passwordandsaltare cloned before they are stored in the newPBEKeySpecobject.- Parameters:
password- the password.salt- the salt.iterationCount- the iteration count.- Throws:
NullPointerException- ifsaltis null.IllegalArgumentException- ifsaltis empty, i.e. 0-length, oriterationCountis not positive.
| Method Detail |
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clearPassword
public final void clearPassword()
- Clears the internal copy of the password.
getPassword
public final char[] getPassword()
- Returns a copy of the password.
Note: this method returns a copy of the password. It is the caller's responsibility to zero out the password information after it is no longer needed.
- Returns:
- the password.
- Throws:
IllegalStateException- if password has been cleared by callingclearPasswordmethod.
getSalt
public final byte[] getSalt()
- Returns a copy of the salt or null if not specified.
Note: this method should return a copy of the salt. It is the caller's responsibility to zero out the salt information after it is no longer needed.
- Returns:
- the salt.
getIterationCount
public final int getIterationCount()
- Returns the iteration count or 0 if not specified.
- Returns:
- the iteration count.
getKeyLength
public final int getKeyLength()
- Returns the to-be-derived key length or 0 if not specified.
Note: this is used to indicate the preference on key length for variable-key-size ciphers. The actual key size depends on each provider's implementation.
- Returns:
- the to-be-derived key length.
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Java™ Platform Standard Ed. 6 |
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For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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