public abstract class JcaCipherService extends Object implements CipherService
CipherService implementation utilizing Java's JCA APIs.
CipherService implementations that the JCA
Cipher does not do: by default,
initialization vectors are automatically randomly
generated and prepended to encrypted data before returning from the encrypt methods. That is, the returned
byte array or OutputStream is actually a concatenation of an initialization vector byte array plus the actual
encrypted data byte array. The decrypt methods in turn know to read this prepended initialization vector
before decrypting the real data that follows.
This is highly desirable because initialization vectors guarantee that, for a key and any plaintext, the encrypted
output will always be different even if you call encrypt multiple times with the exact same arguments.
This is essential in cryptography to ensure that data patterns cannot be identified across multiple input sources
that are the same or similar.
You can turn off this behavior by setting the
generateInitializationVectors property to false, but it
is highly recommended that you do not do this unless you have a very good reason to do so, since you would be losing
a critical security feature.
initializationVectorSize attribute to
128 bits, a fairly common size. Initialization vector sizes are very algorithm specific however, so subclass
implementations will often override this value in their constructor if necessary.
Also note that initializationVectorSize values are specified in the number of
bits (not bytes!) to match common references in most cryptography documentation. In practice though, initialization
vectors are always specified as a byte array, so ensure that if you set this property, that the value is a multiple
of 8 to ensure that the IV can be correctly represented as a byte array (the
setInitializationVectorSize mutator method enforces this).| Modifier | Constructor and Description |
|---|---|
protected |
JcaCipherService(String algorithmName)
Creates a new
JcaCipherService instance which will use the specified cipher algorithmName
for all encryption, decryption, and key operations. |
| Modifier and Type | Method and Description |
|---|---|
ByteSource |
decrypt(byte[] ciphertext,
byte[] key)
Decrypts encrypted data via the specified cipher key and returns the original (pre-encrypted) data.
|
void |
decrypt(InputStream in,
OutputStream out,
byte[] key)
Receives encrypted data from the given
InputStream, decrypts it, and sends the resulting decrypted data
to the given OutputStream. |
ByteSource |
encrypt(byte[] plaintext,
byte[] key)
Encrypts data via the specified cipher key.
|
void |
encrypt(InputStream in,
OutputStream out,
byte[] key)
Receives the data from the given
InputStream, encrypts it, and sends the resulting encrypted data to the
given OutputStream. |
protected SecureRandom |
ensureSecureRandom() |
protected byte[] |
generateInitializationVector(boolean streaming) |
String |
getAlgorithmName()
Returns the cipher algorithm name that will be used for all encryption, decryption, and key operations (for
example, 'AES', 'Blowfish', 'RSA', 'DSA', 'TripleDES', etc).
|
protected static SecureRandom |
getDefaultSecureRandom() |
int |
getInitializationVectorSize()
Returns the algorithm-specific size in bits of generated initialization vectors.
|
int |
getKeySize()
Returns the size in bits (not bytes) of generated cipher keys.
|
SecureRandom |
getSecureRandom()
Returns a source of randomness for encryption operations.
|
int |
getStreamingBufferSize()
Returns the size in bytes of the internal buffer used to transfer data from one stream to another during stream
operations (
encrypt(java.io.InputStream, java.io.OutputStream, byte[]) and
decrypt(java.io.InputStream, java.io.OutputStream, byte[])). |
protected String |
getTransformationString(boolean streaming)
Returns the transformation string to use with the
Cipher.getInstance(java.lang.String) invocation when
creating a new Cipher instance. |
boolean |
isGenerateInitializationVectors() |
protected boolean |
isGenerateInitializationVectors(boolean streaming) |
void |
setGenerateInitializationVectors(boolean generateInitializationVectors) |
void |
setInitializationVectorSize(int initializationVectorSize)
Sets the algorithm-specific initialization vector size in bits (not bytes!) to be used when generating
initialization vectors.
|
void |
setKeySize(int keySize)
Sets the size in bits (not bytes) of generated cipher keys.
|
void |
setSecureRandom(SecureRandom secureRandom)
Sets a source of randomness for encryption operations.
|
void |
setStreamingBufferSize(int streamingBufferSize)
Sets the size in bytes of the internal buffer used to transfer data from one stream to another during stream
operations (
encrypt(java.io.InputStream, java.io.OutputStream, byte[]) and
decrypt(java.io.InputStream, java.io.OutputStream, byte[])). |
protected JcaCipherService(String algorithmName)
JcaCipherService instance which will use the specified cipher algorithmName
for all encryption, decryption, and key operations. Also, the following defaults are set:
keySize = 128 bitsinitializationVectorSize = 128 bitsstreamingBufferSize = 512 bytesalgorithmName - the name of the cipher algorithm to use for all encryption, decryption, and key operationspublic String getAlgorithmName()
public int getKeySize()
public void setKeySize(int keySize)
keySize - the size in bits (not bytes) of generated cipher keys.public boolean isGenerateInitializationVectors()
public void setGenerateInitializationVectors(boolean generateInitializationVectors)
public int getInitializationVectorSize()
public void setInitializationVectorSize(int initializationVectorSize) throws IllegalArgumentException
8 to ensure that the IV can be represented
as a byte array.initializationVectorSize - the size in bits (not bytes) of generated initialization vectors.IllegalArgumentException - if the size is not a multiple of 8.protected boolean isGenerateInitializationVectors(boolean streaming)
public int getStreamingBufferSize()
encrypt(java.io.InputStream, java.io.OutputStream, byte[]) and
decrypt(java.io.InputStream, java.io.OutputStream, byte[])).
Default size is 512 bytes.public void setStreamingBufferSize(int streamingBufferSize)
encrypt(java.io.InputStream, java.io.OutputStream, byte[]) and
decrypt(java.io.InputStream, java.io.OutputStream, byte[])).
Default size is 512 bytes.streamingBufferSize - the size of the internal buffer used to transfer data from one stream to another
during stream operationspublic SecureRandom getSecureRandom()
SHA1PRNG instance will be used by default.SHA1PRNG instance will be used by default.public void setSecureRandom(SecureRandom secureRandom)
SHA1PRNG instance will be used by default.secureRandom - a source of randomness for encryption operations. If one is not configured, and the
underlying algorithm needs one, the JDK SHA1PRNG instance will be used by default.protected static SecureRandom getDefaultSecureRandom()
protected SecureRandom ensureSecureRandom()
protected String getTransformationString(boolean streaming)
Cipher.getInstance(java.lang.String) invocation when
creating a new Cipher instance. This default implementation always returns
getAlgorithmName(). Block cipher implementations will want to override this method
to support appending cipher operation modes and padding schemes.streaming - if the transformation string is going to be used for a Cipher for stream-based encryption or not.Cipher.getInstance(java.lang.String) invocation when
creating a new Cipher instance.protected byte[] generateInitializationVector(boolean streaming)
public ByteSource encrypt(byte[] plaintext, byte[] key)
CipherServiceCipherService implementation.encrypt in interface CipherServiceplaintext - the data to encryptkey - the cipher key used during encryption.public ByteSource decrypt(byte[] ciphertext, byte[] key) throws CryptoException
CipherServicedecrypt in interface CipherServiceciphertext - the previously encrypted data to decryptkey - the cipher key used during decryption.CryptoException - if there is an error during decryptionpublic void encrypt(InputStream in, OutputStream out, byte[] key) throws CryptoException
CipherServiceInputStream, encrypts it, and sends the resulting encrypted data to the
given OutputStream.
NOTE: This method does NOT flush or close either stream prior to returning - the caller must
do so when they are finished with the streams. For example:
try {
InputStream in = ...
OutputStream out = ...
cipherService.encrypt(in, out, encryptionKey);
} finally {
if (in != null) {
try {
in.close();
} catch (IOException ioe1) { ... log, trigger event, etc }
}
if (out != null) {
try {
out.close();
} catch (IOException ioe2) { ... log, trigger event, etc }
}
}
encrypt in interface CipherServicein - the stream supplying the data to encryptout - the stream to send the encrypted datakey - the cipher key to use for encryptionCryptoException - if there is any problem during encryption.public void decrypt(InputStream in, OutputStream out, byte[] key) throws CryptoException
CipherServiceInputStream, decrypts it, and sends the resulting decrypted data
to the given OutputStream.
NOTE: This method does NOT flush or close either stream prior to returning - the caller must
do so when they are finished with the streams. For example:
try {
InputStream in = ...
OutputStream out = ...
cipherService.decrypt(in, out, decryptionKey);
} finally {
if (in != null) {
try {
in.close();
} catch (IOException ioe1) { ... log, trigger event, etc }
}
if (out != null) {
try {
out.close();
} catch (IOException ioe2) { ... log, trigger event, etc }
}
}
decrypt in interface CipherServicein - the stream supplying the data to decryptout - the stream to send the decrypted datakey - the cipher key to use for decryptionCryptoException - if there is any problem during decryption.Copyright © 2004-2016 The Apache Software Foundation. All Rights Reserved.