Hi,
First of all thanks for the time to see my question.
I have a encrypted data that comes from Java webservice(AES256-base64Encoded) :

C5j45mSEdqfz4f4GnrwR2T25tizY5gb3JoVNtWp8DiYOW5d+qvPx/ODmQIQqNXpZ1YkIjLwu5BAjDh3QmlrC4DKwTvbSrVqxh7OJdGDQy60ebp0o1cmLBCJuqzAOh2KAZC6L9v4wkwEb9dFOPesImY15DySPeyYiuLHL7n2dHmyVUMcDUrp9TAm85daCyG5mKhaAy2SP8iNBPoUBWSIDDEM7vG5Ganxu6JVzG4V6zGYQlLXAi33Ct9Fs99YE02KKR4kiw52eE1nS4hwReMZnP4vuU1FxM0BZfWAdUV8m9pQ=
Now I also have a 32 bit key to decode it (base64Encoded):

v3erqY/EGg1NI0yFHYLsMt7IuqJksxNjo1dlhsOo6Zs=

So after decryption, I should get the following data below:

http://b2bfsta.edc.cingular.net:8180/b2bservlets/TCMLoginDispatch.dyn?loginChannel=EBM&uid=B2c18e47fbc6e94ec7e5a92dece2c2684a4e3421a&sourceSystemId=iPhone6-NewOrder&profileType=PLATINUM&peDealId=o31634600562&enableDDR=true

I know if I encrypt in Apex then I can use decrypt(String, Blob, Blob, Blob) or decryptWithManagedIV(String, Blob, Blob).
But in this case, I don't why I am getting error, I tried all options available . PLease find sample code:

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Blob key = EncodingUtil.base64Decode('v3erqY/EGg1NI0yFHYLsMt7IuqJksxNjo1dlhsOo6Zs=');
String encodedData ='C5j45mSEdqfz4f4GnrwR2T25tizY5gb3JoVNtWp8DiYOW5d+qvPx/ODmQIQqNXpZ1YkIjLwu5BAjDh3QmlrC4DKwTvbSrVqxh7OJdGDQy60ebp0o1cmLBCJuqzAOh2KAZC6L9v4wkwEb9dFOPesImY15DySPeyYiuLHL7n2dHmyVUMcDUrp9TAm85daCyG5mKhaAy2SP8iNBPoUBWSIDDEM7vG5Ganxu6JVzG4V6zGYQlLXAi33Ct9Fs99YE02KKR4kiw52eE1nS4hwReMZnP4vuU1FxM0BZfWAdUV8m9pQ=';
Blob exampleIv = Blob.valueOf('Example of IV123');
Blob decryptedData = Crypto.decrypt('AES256', key ,exampleIv, EncodingUtil.base64Decode(encodedData));
//Blob decryptedData = Crypto.decryptWithManagedIV('AES256', key, EncodingUtil.base64Decode(encodedData));
 system.debug(decryptedData );  
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below is the java encrypted code, that can be refer:

public class EncryptionTest {

       public static final String CHAR_SET = "UTF8";
       
       public static void main(String[] args) {
              // TODO Auto-generated method stub
              //System.out.println("Hello World");
              String key = "v3erqY/EGg1NI0yFHYLsMt7IuqJksxNjo1dlhsOo6Zs=";
              
              // Try the below as well
              byte [] mKeyBytes = Base64.decodeBase64(key);
              //byte [] mKeyBytes = decodeToByteArray(key.getBytes());
              
              javax.crypto.Cipher mDecryptCipher = null;
              javax.crypto.Cipher mEncryptCipher = null;
              //byte[] mKeyBytes;
              
              try {
                     // Create the SecretKeySpec using the key in mKeyBytes
                     final SecretKeySpec skeySpec = new SecretKeySpec(mKeyBytes, getAlgorithmName());
                     // Create a new Cipher instance to do decryption using ALGORITHM
                     final javax.crypto.Cipher decryptCipher = javax.crypto.Cipher.getInstance(getAlgorithmName());
                     // Initialize this Cipher as a decryption cipher and pass in the key
                     // spec to use
                     decryptCipher.init(javax.crypto.Cipher.DECRYPT_MODE, skeySpec);
                     // If the previous two steps succeeded, set this new decryption
                     // Cipher to be this class's member decryption Cipher
                     mDecryptCipher = decryptCipher;
                     // Create a new Cipher instance to do encryption using ALGORITHM
                     final javax.crypto.Cipher encryptCipher = javax.crypto.Cipher.getInstance(getAlgorithmName());
                     // Initialize this Cipher as an encryption cipher and pass in the
                     // key spec to us
                     encryptCipher.init(javax.crypto.Cipher.ENCRYPT_MODE, skeySpec);
                     // If the previous two steps succeeded, set this new encryption
                     // Cipher to be this class's member encryption Cipher
                     mEncryptCipher = encryptCipher;
              } catch (InvalidKeyException e) {
                     System.out.println(e.getMessage());
                     e.printStackTrace();
              } catch (NoSuchAlgorithmException e) {
                     System.out.println(e.getMessage());
                     e.printStackTrace();
              } catch (NoSuchPaddingException e) {
                     System.out.println(e.getMessage());
                     e.printStackTrace();
              }
              
              String pStringToDecrypt = "C5j45mSEdqfz4f4GnrwR2T25tizY5gb3JoVNtWp8DiYOW5d+qvPx/ODmQIQqNXpZ1YkIjLwu5BAjDh3QmlrC4DKwTvbSrVqxh7OJdGDQy60ebp0o1cmLBCJuqzAOh2KAZC6L9v4wkwEb9dFOPesImY15DySPeyYiuLHL7n2dHmyVUMcDUrp9TAm85daCyG5mKhaAy2SP8iNBPoUBWSIDDEM7vG5Ganxu6JVzG4V6zGYQlLXAi33Ct9Fs99YE02KKR4kiw52eE1nS4hwReMZnP4vuU1FxM0BZfWAdUV8m9pQ=";
              
              //System.out.println("Hello");
              
              String decryptedString;
              final byte[] encryptedBytes;
              final byte[] decryptedBytes;
        try {
              encryptedBytes = Base64.decodeBase64(pStringToDecrypt.getBytes(CHAR_SET));
              decryptedBytes = decrypt(mDecryptCipher, encryptedBytes);
            decryptedString = new String(decryptedBytes, CHAR_SET);
            System.out.println(decryptedString);
        } catch (UnsupportedEncodingException e) {
              System.out.println(e.getMessage());
              e.printStackTrace();
        } catch (Exception e) {
              System.out.println(e.getMessage());
              e.printStackTrace();
        }
        
       }
       
       protected static final byte[] decrypt(javax.crypto.Cipher decryptCipher, byte[] pBytesToDecrypt) throws Exception {
              try {
                     return decryptCipher.doFinal(pBytesToDecrypt);
              } catch (IllegalBlockSizeException ibse) {
                     ibse.printStackTrace();
                     throw new Exception("Failed to decrypt: ", ibse);
              } catch (BadPaddingException bpe) {
                     bpe.printStackTrace();
                     throw new Exception("Failed to decrypt: ", bpe);
              }
       }

       public static String getAlgorithmName() {
              return "AES";
       }

}
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The problem is that the encrypted code is not getting decrypted in apex using standard way . Please help me out.