org.jasypt.encryption.pbe

Class StandardPBEStringEncryptor

java.lang.Object

org.jasypt.encryption.pbe.StandardPBEStringEncryptor

All Implemented Interfaces:

CleanablePasswordBased, PasswordBased, PBEStringCleanablePasswordEncryptor, PBEStringEncryptor, StringEncryptor

public final class StandardPBEStringEncryptor
extends Object
implements PBEStringCleanablePasswordEncryptor

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.

And the actual values to be used for initialization will be established by applying the following priorities:

1. First, the default values are considered (except for password).
2. Then, if a PBEConfig object has been set with setConfig(...), the non-null values returned by its getX() methods override the default values.
3. 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.

Once an encryptor has been initialized, trying to change its configuration will result in an AlreadyInitializedException being thrown.

Usage

An encryptor may be used for:

• Encrypting messages, by calling the encrypt(...) method.
• Decrypting messages, by calling the decrypt(...) method.

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.

To learn more about the mechanisms involved in encryption, read PKCS #5: Password-Based Cryptography Standard.

Since:

1.0

Author:

Daniel Fernández

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_STRING_OUTPUT_TYPE Default type of String output.

Constructor Summary

Constructors

Constructor and Description
StandardPBEStringEncryptor() Creates a new instance of StandardPBEStringEncryptor.

Method Summary

Modifier and Type	Method and Description
String	decrypt(String encryptedMessage) Decrypts a message using the specified configuration.
String	encrypt(String message) Encrypts a message using the specified configuration.
void	initialize() Initialize the encryptor.
boolean	isInitialized() 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	setConfig(PBEConfig config) Sets a PBEConfig object for the encryptor.
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.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_STRING_OUTPUT_TYPE

public static final String DEFAULT_STRING_OUTPUT_TYPE

Default type of String output. Set to BASE64.

See Also:

Constant Field Values

Constructor Detail

StandardPBEStringEncryptor

public StandardPBEStringEncryptor()

Creates a new instance of StandardPBEStringEncryptor.

Method Detail

setConfig

public void setConfig(PBEConfig config)

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.

setAlgorithm

public void setAlgorithm(String algorithm)

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.

setPassword

public void setPassword(String password)

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 interface PasswordBased

Parameters:

password - the password to be used.

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 interface CleanablePasswordBased

Parameters:

password - the password to be used.

Since:

1.8

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

setSaltGenerator

public void setSaltGenerator(SaltGenerator saltGenerator)

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.

setProviderName

public void setProviderName(String providerName)

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 this setProviderName(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

setProvider

public void setProvider(Provider provider)

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

public void setStringOutputType(String stringOutputType)

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

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.

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:

1. First, the default values are considered (except for password).
2. Then, if a PBEConfig object has been set with setConfig, the non-null values returned by its getX methods override the default values.
3. 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).

encrypt

public String encrypt(String message)

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 interface StringEncryptor

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).

decrypt

public String decrypt(String encryptedMessage)

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 interface StringEncryptor

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).