Format of AES, Blowfish, Twofish, 3DES, etc. Symmetric Encrypted Data?

Question: I know it isn’t listed in the documentation, but is there any method to test whether a file has been previously encrypted or not?  I would like to perform decryption on a file, but only if it is already encrypted. Answer: A symmetric encryption algorithm is simply a transformation of bytes such that the output has the properties of […]