Class StandardPBEStringEncryptor
- All Implemented Interfaces:
CleanablePasswordBased
,PasswordBased
,PBEStringCleanablePasswordEncryptor
,PBEStringEncryptor
,StringEncryptor
Standard implementation of the PBEStringEncryptor
interface.
This class lets the user specify the algorithm (and provider) to be used for
encryption, the password to use,
the number of hashing iterations and the salt generator
that will be applied for obtaining
the encryption key.
This class avoids byte-conversion problems related to the fact of different platforms having different default charsets, and returns encryption results in the form of BASE64-encoded or HEXADECIMAL ASCII Strings.
This class is thread-safe.
Configuration
The algorithm, provider, password, key-obtention iterations and salt generator can take values in any of these ways:
- Using its default values (except for password).
- Setting a
PBEConfig
object which provides new configuration values. - Calling the corresponding setX(...) methods.
- First, the default values are considered (except for password).
- Then, if a
PBEConfig
object has been set with setConfig(...), the non-null values returned by its getX() methods override the default values. - Finally, if the corresponding setX(...) method has been called on the encryptor itself for any of the configuration parameters, the values set by these calls override all of the above.
Initialization
Before it is ready to encrypt, an object of this class has to be initialized. Initialization happens:
- When initialize() is called.
- When encrypt(...) or decrypt(...) are called for the first time, if initialize() has not been called before.
Usage
An encryptor may be used for:
- Encrypting messages, by calling the encrypt(...) method.
- Decrypting messages, by calling the decrypt(...) method.
To learn more about the mechanisms involved in encryption, read PKCS #5: Password-Based Cryptography Standard.
- Since:
- 1.0
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate final Base64
private final StandardPBEByteEncryptor
static final String
Default type of String output.private static final String
Charset to be used for encoding the encryption results.private static final String
Charset to be used to obtain "encryptable" byte arrays from input Strings.private String
private boolean
private boolean
private StringPBEConfig
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Constructor Summary
ConstructorsModifierConstructorDescriptionCreates a new instance of StandardPBEStringEncryptor.private
StandardPBEStringEncryptor
(StandardPBEByteEncryptor standardPBEByteEncryptor) -
Method Summary
Modifier and TypeMethodDescription(package private) StandardPBEStringEncryptor[]
cloneAndInitializeEncryptor
(int size) Decrypts a message using the specified configuration.Encrypts a message using the specified configuration.void
Initialize the encryptor.private void
boolean
Returns true if the encryptor has already been initialized, false if not.
Initialization happens:void
setAlgorithm
(String algorithm) Sets the algorithm to be used for encryption, like PBEWithMD5AndDES.void
Sets aPBEConfig
object for the encryptor.void
setIvGenerator
(IvGenerator ivGenerator) Sets the IV generator to be used.void
setKeyObtentionIterations
(int keyObtentionIterations) Set the number of hashing iterations applied to obtain the encryption key.void
setPassword
(String password) Sets the password to be used.void
setPasswordCharArray
(char[] password) Sets the password to be used, as a char[].void
setProvider
(Provider provider) Sets the security provider to be asked for the encryption algorithm.void
setProviderName
(String providerName) Sets the name of the security provider to be asked for the encryption algorithm.void
setSaltGenerator
(SaltGenerator saltGenerator) Sets the salt generator to be used.void
setStringOutputType
(String stringOutputType) Sets the the form in which String output will be encoded.
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Field Details
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MESSAGE_CHARSET
Charset to be used to obtain "encryptable" byte arrays from input Strings. Set to UTF-8.
This charset has to be fixed to some value so that we avoid problems with different platforms having different "default" charsets.
It is set to UTF-8 because it covers the whole spectrum of characters representable in Java (which internally uses UTF-16), and avoids the size penalty of UTF-16 (which will always use two bytes for representing each character, even if it is an ASCII one).
Setting it to UTF-8 does not mean that Strings that originally come, for example, from an ISO-8859-1 input, won't be correctly encoded, as we only need to use the same charset both when encoding and decoding. That way the same String will be reconstructed independently of the original encoding (for encrypting, we only need "a byte representation" of the string, not "a readable byte representation").
- See Also:
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ENCRYPTED_MESSAGE_CHARSET
Charset to be used for encoding the encryption results. Set to US-ASCII.
The result of encrypting some bytes can be any other bytes, and so the result of encrypting, for example, some LATIN-1 valid String bytes, can be bytes that may not conform a "valid" LATIN-1 String.
Because of this, encryption results are always encoded in BASE64 (default) or HEXADECIMAL after being created, and this ensures that the results will make perfectly representable, safe ASCII Strings. Because of this, the charset used to convert the encrypted bytes to the returned String is set to US-ASCII.
- See Also:
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DEFAULT_STRING_OUTPUT_TYPE
Default type of String output. Set to BASE64.
- See Also:
-
stringPBEConfig
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stringOutputType
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stringOutputTypeBase64
private boolean stringOutputTypeBase64 -
stringOutputTypeSet
private boolean stringOutputTypeSet -
byteEncryptor
-
base64
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Constructor Details
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StandardPBEStringEncryptor
public StandardPBEStringEncryptor()Creates a new instance of StandardPBEStringEncryptor. -
StandardPBEStringEncryptor
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Method Details
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setConfig
Sets a
PBEConfig
object for the encryptor. If this config object is set, it will be asked values for:- Algorithm
- Security Provider (or provider name)
- Password
- Hashing iterations for obtaining the encryption key
- Salt generator
- Output type (base64, hexadecimal) (only StringPBEConfig)
The non-null values it returns will override the default ones, and will be overriden by any values specified with a setX method.
- Parameters:
config
- the PBEConfig object to be used as the source for configuration parameters.
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setAlgorithm
Sets the algorithm to be used for encryption, like PBEWithMD5AndDES.
This algorithm has to be supported by your JCE provider (if you specify one, or the default JVM provider if you don't) and, if it is supported, you can also specify mode and padding for it, like ALGORITHM/MODE/PADDING.
- Parameters:
algorithm
- the name of the algorithm to be used.
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setPassword
Sets the password to be used.
There is no default value for password, so not setting this parameter either from a
PBEConfig
object or from a call to setPassword will result in an EncryptionInitializationException being thrown during initialization.- Specified by:
setPassword
in interfacePasswordBased
- Parameters:
password
- the password to be used.
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setPasswordCharArray
public void setPasswordCharArray(char[] password) Sets the password to be used, as a char[].
This allows the password to be specified as a cleanable char[] instead of a String, in extreme security conscious environments in which no copy of the password as an immutable String should be kept in memory.
Important: the array specified as a parameter WILL BE COPIED in order to be stored as encryptor configuration. The caller of this method will therefore be responsible for its cleaning (jasypt will only clean the internally stored copy).
There is no default value for password, so not setting this parameter either from a
PBEConfig
object or from a call to setPassword will result in an EncryptionInitializationException being thrown during initialization.- Specified by:
setPasswordCharArray
in interfaceCleanablePasswordBased
- Parameters:
password
- the password to be used.- Since:
- 1.8
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setKeyObtentionIterations
public void setKeyObtentionIterations(int keyObtentionIterations) Set the number of hashing iterations applied to obtain the encryption key.
This mechanism is explained in PKCS #5: Password-Based Cryptography Standard.
- Parameters:
keyObtentionIterations
- the number of iterations
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setSaltGenerator
Sets the salt generator to be used. If no salt generator is specified, an instance of
RandomSaltGenerator
will be used.- Parameters:
saltGenerator
- the salt generator to be used.
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setIvGenerator
Sets the IV generator to be used. If no IV generator is specified, an instance of
NoIvGenerator
will be used.- Parameters:
ivGenerator
- the IV generator to be used.
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setProviderName
Sets the name of the security provider to be asked for the encryption algorithm. This security provider has to be registered beforehand at the JVM security framework.
The provider can also be set with the
setProvider(Provider)
method, in which case it will not be necessary neither registering the provider beforehand, nor calling thissetProviderName(String)
method to specify a provider name.Note that a call to
setProvider(Provider)
overrides any value set by this method.If no provider name / provider is explicitly set, the default JVM provider will be used.
- Parameters:
providerName
- the name of the security provider to be asked for the encryption algorithm.- Since:
- 1.3
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setProvider
Sets the security provider to be asked for the encryption algorithm. The provider does not have to be registered at the security infrastructure beforehand, and its being used here will not result in its being registered.
If this method is called, calling
setProviderName(String)
becomes unnecessary.If no provider name / provider is explicitly set, the default JVM provider will be used.
- Parameters:
provider
- the provider to be asked for the chosen algorithm- Since:
- 1.3
-
setStringOutputType
Sets the the form in which String output will be encoded. Available encoding types are:
- base64 (default)
- hexadecimal
If not set, null will be returned.
- Parameters:
stringOutputType
- the string output type.- Since:
- 1.3
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cloneAndInitializeEncryptor
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isInitialized
public boolean isInitialized()Returns true if the encryptor has already been initialized, false if not.
Initialization happens:- When initialize is called.
- When encrypt or decrypt are called for the first time, if initialize has not been called before.
Once an encryptor has been initialized, trying to change its configuration will result in an AlreadyInitializedException being thrown.
- Returns:
- true if the encryptor has already been initialized, false if not.
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initialize
public void initialize()Initialize the encryptor.
This operation will consist in determining the actual configuration values to be used, and then initializing the encryptor with them.
These values are decided by applying the following priorities:- First, the default values are considered (except for password).
- Then, if a
PBEConfig
object has been set with setConfig, the non-null values returned by its getX methods override the default values. - Finally, if the corresponding setX method has been called on the encryptor itself for any of the configuration parameters, the values set by these calls override all of the above.
Once an encryptor has been initialized, trying to change its configuration will result in an AlreadyInitializedException being thrown.
- Throws:
EncryptionInitializationException
- if initialization could not be correctly done (for example, no password has been set).
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initializeSpecifics
private void initializeSpecifics() -
encrypt
Encrypts a message using the specified configuration.
The Strings returned by this method are BASE64-encoded (default) or HEXADECIMAL ASCII Strings.The mechanisms applied to perform the encryption operation are described in PKCS #5: Password-Based Cryptography Standard.
This encryptor uses a salt for each encryption operation. The size of the salt depends on the algorithm being used. This salt is used for creating the encryption key and, if generated by a random generator, it is also appended unencrypted at the beginning of the results so that a decryption operation can be performed.
If a random salt generator is used, two encryption results for the same message will always be different (except in the case of random salt coincidence). This may enforce security by difficulting brute force attacks on sets of data at a time and forcing attackers to perform a brute force attack on each separate piece of encrypted data.
- Specified by:
encrypt
in interfaceStringEncryptor
- Parameters:
message
- the String message to be encrypted- Returns:
- the result of encryption
- Throws:
EncryptionOperationNotPossibleException
- if the encryption operation fails, ommitting any further information about the cause for security reasons.EncryptionInitializationException
- if initialization could not be correctly done (for example, no password has been set).
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decrypt
Decrypts a message using the specified configuration.
This method expects to receive a BASE64-encoded (default) or HEXADECIMAL ASCII String.
The mechanisms applied to perform the decryption operation are described in PKCS #5: Password-Based Cryptography Standard.
If a random salt generator is used, this decryption operation will expect to find an unencrypted salt at the beginning of the encrypted input, so that the decryption operation can be correctly performed (there is no other way of knowing it).
- Specified by:
decrypt
in interfaceStringEncryptor
- Parameters:
encryptedMessage
- the String message to be decrypted- Returns:
- the result of decryption
- Throws:
EncryptionOperationNotPossibleException
- if the decryption operation fails, ommitting any further information about the cause for security reasons.EncryptionInitializationException
- if initialization could not be correctly done (for example, no password has been set).
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