Jasypt的StandardPBEByteEncryptor使用源码解析

StrongPasswordEncryptor passwordEncryptor = new StrongPasswordEncryptor();
String encryptedPassword = passwordEncryptor.encryptPassword(userPassword);
...
if (passwordEncryptor.checkPassword(inputPassword, encryptedPassword)) {
  // correct!
} else {
  // bad login!
}

AES256TextEncryptor textEncryptor = new AES256TextEncryptor();
textEncryptor.setPassword(myEncryptionPassword);
String myEncryptedText = textEncryptor.encrypt(myText);
...
String plainText = textEncryptor.decrypt(myEncryptedText);

public final class StandardPBEByteEncryptor implements PBEByteCleanablePasswordEncryptor {
    /**
     * The default algorithm to be used if none specified: PBEWithMD5AndDES.
     */
    public static final String DEFAULT_ALGORITHM = "PBEWithMD5AndDES";
    /**
     * The default number of hashing iterations applied for obtaining the encryption key from the specified password,
     * set to 1000.
     */
    public static final int DEFAULT_KEY_OBTENTION_ITERATIONS = 1000;
    /**
     * The default salt size, only used if the chosen encryption algorithm is not a block algorithm and thus block size
     * cannot be used as salt size.
     */
    public static final int DEFAULT_SALT_SIZE_BYTES = 8;
    /**
     * The default IV size
     */
    public static final int IV_SIZE_IN_BITS = 128;
    // Algorithm (and provider-related info) for Password Based Encoding.
    private String algorithm = DEFAULT_ALGORITHM;
    private String providerName = null;
    private Provider provider = null;
    // Password to be applied. This will NOT have a default value. If none
    // is set during configuration, an exception will be thrown.
    private char[] password = null;
    // Number of hashing iterations to be applied for obtaining the encryption
    // key from the specified password.
    private int keyObtentionIterations = DEFAULT_KEY_OBTENTION_ITERATIONS;
    // SaltGenerator to be used. Initialization of a salt generator is costly,
    // and so default value will be applied only in initialize(), if it finally
    // becomes necessary.
    private SaltGenerator saltGenerator = null;
    // IVGenerator to initialise IV
    private IVGenerator ivGenerator = null;
    // Size in bytes of the IV to be used
    private final int IVSizeBytes = IV_SIZE_IN_BITS;
    // Size in bytes of the salt to be used for obtaining the
    // encryption key. This size will depend on the PBE algorithm being used,
    // and it will be set to the size of the block for the specific
    // chosen algorithm (if the algorithm is not a block algorithm, the
    // default value will be used).
    private int saltSizeBytes = DEFAULT_SALT_SIZE_BYTES;
    //......
}

public interface ByteEncryptor {
    
    
    /**
     * Encrypt the input message
     * 
     * @param message the message to be encrypted
     * @return the result of encryption
     */
    public byte[] encrypt(byte[] message);

    /**
     * Decrypt an encrypted message
     * 
     * @param encryptedMessage the encrypted message to be decrypted
     * @return the result of decryption
     */
    public byte[] decrypt(byte[] encryptedMessage);
    
}

public byte[] encrypt(final byte[] message) throws EncryptionOperationNotPossibleException {
        if (message == null) {
            return null;
        }
        // Check initialization
        if (!isInitialized()) {
            initialize();
        }
        try {
            final byte[] salt;
            byte[] iv = null;
            final byte[] encryptedMessage;
            if (usingFixedSalt) {
                salt = fixedSaltInUse;
                synchronized (encryptCipher) {
                    encryptedMessage = encryptCipher.doFinal(message);
                }
            }
            else {
                // Create salt
                salt = saltGenerator.generateSalt(saltSizeBytes);
                // Create the IV
                iv = ivGenerator.generateIV(IVSizeBytes);
                IvParameterSpec ivParameterSpec = null;
                if (iv != null) {
                    ivParameterSpec = new IvParameterSpec(iv);
                }
                /*
                 * Perform encryption using the Cipher
                 */
                final PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, keyObtentionIterations,
                            ivParameterSpec);
                synchronized (encryptCipher) {
                    encryptCipher.init(Cipher.ENCRYPT_MODE, key, parameterSpec);
                    encryptedMessage = encryptCipher.doFinal(message);
                }
            }
            byte[] encryptedMessageWithIV = encryptedMessage;
            if (ivGenerator.includePlainIVInEncryptionResults()) {
                encryptedMessageWithIV = CommonUtils.appendArrays(iv, encryptedMessage);
            }
            // Finally we build an array containing both the unencrypted salt
            // and the result of the encryption. This is done only
            // if the salt generator we are using specifies to do so.
            if (saltGenerator.includePlainSaltInEncryptionResults()) {
                // Insert unhashed salt before the encryption result
                final byte[] encryptedMessageWithIVAndSalt = CommonUtils.appendArrays(salt, encryptedMessageWithIV);
                return encryptedMessageWithIVAndSalt;
            }
            return encryptedMessageWithIV;
        }
        catch (final InvalidKeyException e) {
            // The problem could be not having the unlimited strength policies
            // installed, so better give a usefull error message.
            handleInvalidKeyException(e);
            throw new EncryptionOperationNotPossibleException();
        }
        catch (final Exception e) {
            // If encryption fails, it is more secure not to return any
            // information about the cause in nested exceptions. Simply fail.
            throw new EncryptionOperationNotPossibleException();
        }
    }

public byte[] decrypt(final byte[] encryptedMessage) throws EncryptionOperationNotPossibleException {
        if (encryptedMessage == null) {
            return null;
        }
        // Check initialization
        if (!isInitialized()) {
            initialize();
        }
        if (saltGenerator.includePlainSaltInEncryptionResults()) {
            // Check that the received message is bigger than the salt
            if (encryptedMessage.length <= saltSizeBytes) {
                throw new EncryptionOperationNotPossibleException();
            }
        }
        // if (this.ivGenerator.includePlainIVInEncryptionResults()) {
        // // Check that the received message is bigger than the IV
        // if (encryptedMessage.length <= this.IVSizeBytes) {
        // throw new EncryptionOperationNotPossibleException();
        // }
        // }
        try {
            // If we are using a salt generator which specifies the salt
            // to be included into the encrypted message itself, get it from
            // there. If not, the salt is supposed to be fixed and thus the
            // salt generator can be safely asked for it again.
            byte[] salt = null;
            byte[] encryptedMessageKernel = null;
            if (saltGenerator.includePlainSaltInEncryptionResults()) {
                final int saltStart = 0;
                final int saltSize = saltSizeBytes < encryptedMessage.length ? saltSizeBytes : encryptedMessage.length;
                final int encMesKernelStart = saltSizeBytes < encryptedMessage.length ? saltSizeBytes
                            : encryptedMessage.length;
                final int encMesKernelSize = saltSizeBytes < encryptedMessage.length
                            ? encryptedMessage.length - saltSizeBytes
                            : 0;
                salt = new byte[saltSize];
                encryptedMessageKernel = new byte[encMesKernelSize];
                System.arraycopy(encryptedMessage, saltStart, salt, 0, saltSize);
                System.arraycopy(encryptedMessage, encMesKernelStart, encryptedMessageKernel, 0, encMesKernelSize);
            }
            else if (!usingFixedSalt) {
                salt = saltGenerator.generateSalt(saltSizeBytes);
                encryptedMessageKernel = encryptedMessage;
            }
            else {
                // this.usingFixedSalt == true
                salt = fixedSaltInUse;
                encryptedMessageKernel = encryptedMessage;
            }
            // Logic for IV
            byte[] finalEncryptedMessage;
            byte[] iv;
            if (ivGenerator.includePlainIVInEncryptionResults()) {
                // Extracting the IV
                iv = Arrays.copyOfRange(encryptedMessageKernel, 0, IVSizeBytes / 8);
                finalEncryptedMessage = Arrays.copyOfRange(encryptedMessageKernel, iv.length,
                            encryptedMessageKernel.length);
            }
            else {
                // Fixed IV
                finalEncryptedMessage = encryptedMessageKernel;
                iv = ivGenerator.generateIV(IVSizeBytes);
            }
            final byte[] decryptedMessage;
            if (usingFixedSalt) {
                /*
                 * Fixed salt is being used, therefore no initialization supposedly needed
                 */
                synchronized (decryptCipher) {
                    decryptedMessage = decryptCipher.doFinal(encryptedMessageKernel);
                }
            }
            else {
                /*
                 * Perform decryption using the Cipher
                 */
                IvParameterSpec ivParameterSpec = null;
                if (iv != null) {
                    ivParameterSpec = new IvParameterSpec(iv);
                }
                final PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, keyObtentionIterations,
                            ivParameterSpec);
                synchronized (decryptCipher) {
                    decryptCipher.init(Cipher.DECRYPT_MODE, key, parameterSpec);
                    decryptedMessage = decryptCipher.doFinal(finalEncryptedMessage);
                }
            }
            // Return the results
            return decryptedMessage;
        }
        catch (final InvalidKeyException e) {
            // The problem could be not having the unlimited strength policies
            // installed, so better give a usefull error message.
            handleInvalidKeyException(e);
            throw new EncryptionOperationNotPossibleException();
        }
        catch (final Exception e) {
            // If decryption fails, it is more secure not to return any
            // information about the cause in nested exceptions. Simply fail.
            throw new EncryptionOperationNotPossibleException();
        }
    }