encrypted-message = 
U2FsdGVkX1+FCYr3e5DJDDdz1B5ZtQvpiaieRJrSSSw3c9QeWbUL6YmonkSa0kks
J1Jj8Oq4aNhDRADdt+1iPC9hIg87liKbVEc2fqBM8lsiG0oyACgRxJ3oy1XTnAZX
lucGqmLnCsqSbwO6N1uANt1pRXJFCefgGvZ3fAherCsZP297KVp7aXCORA8Tk0tN
N3PUHlm1C+mJqJ5EmtJJLDdz1B5ZtQvpiaieRJrSSSw5wFphGyd+gWYQ5OgCej2X 

The password to decrypt this message uses the following pattern:

   blocksize-cyphermode  (in lowercase)

To figure out the password, use a tool like Burp to analyze the cyphertext above to determine the block size and cypher mode used to encrypt the message.  For example, if the block size used was 8 bytes and you found telltale signs that it used Cypher Block Chaining (CBC), the password would be "8-cbc".  Remember that you can't do analysis of the cyphertext above in its current form...

Once you the have password, use a tool like openssl to decrypt the message using the correct algorithm.