File	Doc	Category	Size	Date	Package
Cipher.java	API Doc	phoneME MR2 API (J2ME)	16033	Wed May 02 18:00:38 BST 2007	javax.crypto

Cipher

• java.lang.Object

Cipher c = Cipher.getInstance("DES/CBC/PKCS5Padding");

Fields Summary
public static final int	ENCRYPT_MODE Constant used to initialize cipher to encryption mode.
public static final int	DECRYPT_MODE Constant used to initialize cipher to decryption mode.
private com.sun.midp.crypto.Cipher	cipher Cipher implementation object.

Constructors Summary
private Cipher(com.sun.midp.crypto.Cipher cipher) Creates a Cipher object. param cipher cipher implementation of algorithm is being used this.cipher = cipher;

Methods Summary
public final int	doFinal(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this cipher was initialized. The first inputLen bytes in the input buffer, starting at inputOffset inclusive, and any input bytes that may have been buffered during a previous update operation, are processed, with padding (if requested) being applied. The result is stored in the output buffer, starting at outputOffset inclusive. If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. Upon finishing, this method resets this cipher object to the state it was in when previously initialized via a call to init. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to init) more data. Note: if any exception is thrown, this cipher object may need to be reset before it can be used again. Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer. param input the input buffer param inputOffset the offset in input where the input starts param inputLen the input length param output the buffer for the result param outputOffset the offset in output where the result is stored return the number of bytes stored in output exception IllegalStateException if this cipher is in a wrong state (e.g., has not been initialized) exception IllegalBlockSizeException if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size exception ShortBufferException if the given output buffer is too small to hold the result exception BadPaddingException if this cipher is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes try { return cipher.doFinal(input, inputOffset, inputLen, output, outputOffset); } catch (com.sun.midp.crypto.ShortBufferException e) { throw new ShortBufferException(e.getMessage()); } catch (com.sun.midp.crypto.IllegalBlockSizeException e) { throw new IllegalBlockSizeException(e.getMessage()); } catch (com.sun.midp.crypto.BadPaddingException e) { throw new BadPaddingException(e.getMessage()); }
public final byte[]	getIV() Returns the initialization vector (IV) in a new buffer. This is useful in the case where a random IV was created. return the initialization vector in a new buffer, or null if the underlying algorithm does not use an IV, or if the IV has not yet been set. return cipher.getIV();
public static final javax.crypto.Cipher	getInstance(java.lang.String transformation) Generates a Cipher object that implements the specified transformation. param transformation the name of the transformation, e.g., DES/CBC/PKCS5Padding. See Appendix A in the Java Cryptography Extension Reference Guide for information about standard transformation names. return a cipher that implements the requested transformation exception NoSuchAlgorithmException if the specified transformation is not available exception NoSuchPaddingException if transformation contains a padding scheme that is not available. try { return new Cipher(com.sun.midp.crypto.Cipher.getInstance(transformation)); } catch (com.sun.midp.crypto.NoSuchAlgorithmException e) { throw new NoSuchAlgorithmException(e.getMessage()); } catch (com.sun.midp.crypto.NoSuchPaddingException e) { throw new NoSuchPaddingException(e.getMessage()); }
public final void	init(int opmode, java.security.Key key) Initializes this cipher with a key. The cipher is initialized for one of the following operations: encryption, decryption, depending on the value of opmode. If this cipher requires any algorithm parameters that cannot be derived from the given key, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption, and raise an InvalidKeyException if it is being initialized for decryption. Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it. param opmode the operation mode of this cipher (this is one of the following: ENCRYPT_MODE or DECRYPT_MODE) param key the key exception InvalidKeyException if the given key is inappropriate for initializing this cipher, or if this cipher is being initialized for decryption and requires algorithm parameters that cannot be determined from the given key, or if the given key has a keysize that exceeds the maximum allowable keysize. try { init(opmode, key, null); } catch (InvalidAlgorithmParameterException e) { throw new InvalidKeyException(); }
public final void	init(int opmode, java.security.Key key, java.security.spec.AlgorithmParameterSpec params) Initializes this cipher with a key and a set of algorithm parameters. The cipher is initialized for one of the following operations: encryption or decryption depending on the value of opmode. If this cipher requires any algorithm parameters and params is null, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption, and raise an InvalidAlgorithmParameterException if it is being initialized for decryption. Note that when a Cipher object is initialized, it loses all previously-acquired state. In other words, initializing a Cipher is equivalent to creating a new instance of that Cipher and initializing it. param opmode the operation mode of this cipher (this is one of the following: ENCRYPT_MODE or DECRYPT_MODE) param key the encryption key param params the algorithm parameters exception InvalidKeyException if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize. exception InvalidAlgorithmParameterException if the given algorithm parameters are inappropriate for this cipher, or this cipher is being initialized for decryption and requires algorithm parameters and params is null, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits. com.sun.midp.crypto.Key cipherKey; com.sun.midp.crypto.CryptoParameter cryptoParameter; if (opmode == DECRYPT_MODE) { opmode = com.sun.midp.crypto.Cipher.DECRYPT_MODE; } else if (opmode == ENCRYPT_MODE) { opmode = com.sun.midp.crypto.Cipher.ENCRYPT_MODE; } else { throw new IllegalArgumentException("Wrong operation mode"); } if (key instanceof SecretKeySpec) { SecretKeySpec temp = (SecretKeySpec)key; byte[] secret = key.getEncoded(); cipherKey = new com.sun.midp.crypto.SecretKey( secret, 0, secret.length, key.getAlgorithm()); } else if (key instanceof RSAPublicKey) { RSAPublicKey temp = (RSAPublicKey)key; cipherKey = temp.getKey(); } else { throw new InvalidKeyException(); } if (params == null) { cryptoParameter = null; } else if (params instanceof IvParameterSpec) { byte[] iv = ((IvParameterSpec)params).getIV(); cryptoParameter = new com.sun.midp.crypto.IvParameter( iv, 0, iv.length); } else { throw new InvalidAlgorithmParameterException(); } try { cipher.init(opmode, cipherKey, cryptoParameter); } catch (com.sun.midp.crypto.InvalidKeyException e) { throw new InvalidKeyException(e.getMessage()); } catch (com.sun.midp.crypto.InvalidAlgorithmParameterException e) { throw new InvalidAlgorithmParameterException(e.getMessage()); }
public final int	update(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) Continues a multiple-part encryption or decryption operation (depending on how this cipher was initialized), processing another data part. The first inputLen bytes in the input buffer, starting at inputOffset inclusive, are processed, and the result is stored in the output buffer, starting at outputOffset inclusive. If the output buffer is too small to hold the result, a ShortBufferException is thrown. In this case, repeat this call with a larger output buffer. If inputLen is zero, this method returns a length of zero. Note: this method should be copy-safe, which means the input and output buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer. param input the input buffer param inputOffset the offset in input where the input starts param inputLen the input length param output the buffer for the result param outputOffset the offset in output where the result is stored return the number of bytes stored in output exception IllegalStateException if this cipher is in a wrong state (e.g., has not been initialized) exception ShortBufferException if the given output buffer is too small to hold the result try { return cipher.update(input, inputOffset, inputLen, output, outputOffset); } catch (com.sun.midp.crypto.ShortBufferException e) { throw new ShortBufferException(e.getMessage()); }