During the process of encryption and decryption keys shared cry.ptography system

During the process of encryption and decryption keys shared cry.ptography system Interting qution, but lets ask this is a different way and exclude quantum computing as an at.tack vector. I have information file, email, data, etc. that has been encrypted. Is it possible to obtain the plain text or unencrypted information? Its important to understand the difference between a hashing algorithm and an encryption algorithm Whats The Difference Between Hashing and Encrypting? . Ill focus on encryption for this answer. It can also make a difference if something is encrypted with symmetric one key or asymmetric two key encryption. Difference between asymmetric and symmetric encryption methods? . Ill focus on symmetric encryption like AES, 3DES, Blowfish, RC4, etc. If you dont have the decryption key, then you can use one of the following methods to obtain the original information Brute force by trying every theoretically possible encryption key. For 128 bit AES, this is practically impossible cant be done using current technology and computing power. 256 bit AES is exponentially more difficult. If you know the algorithm AND process used to generate the encrypted information, you can try to guess what the original information was. For example, if the encrypted information is a password, then I could write a program to take a large list of common passwords, encrypt each password, and then compare to the encrypted text. If they matched, then I would have my answer. This can wor.k for very simple situations, but not useful for large amounts of encrypted information. Since brute force doesnt wor.k well for modern encryption algorithms, we need to find a way to get the decryption key more easily. Some methods to make this easier are Guess the key if the original encryption key was derived from a manually chosen password, maybe the person picked a very simple password. This is similar to someone choosing a very simple WPA WiFi password. Steal the key if you have access to the computer used to encrypt/decrypt information maybe you can steal the key using a keystroke logger, malware that reads memory, or even physical coercion. Find a way to reduce the number of decryption keys you have to guess. Maybe there is a flaw in the algorithm obtained via Cryptanalysis . You might find that the method used to generate the original encryption was weak such as a problem with the Initialization vector WEP is broken because of this. It is important to understand that if the only way for an at.tacker to decrypt information is by a brute force at.tack that requires searching through all possible decryption keys, then YOU HAVE NOT BROKEN THE ALGORITHM. It functioned as designed, and us good guys need to use an algorithm with a longer key length AES 256 versus AES 128 for example. If an at.tacker used cryptanalysis to find a mechanism to reduce the number of decryption keys required to obtain the original information, then the encryption process used can be said to be broken or weakened. Quantum computing is making very quick progress to being a viable method to at.tack public/private key encryption in the future writing this on 3/9/2020. In co.ntrast to the threat quantum computing poses to current public key algorithms, most current symmetric cryographic algorithms and hash functions are co.nsidered to be relatively secure against at.tacks by quantum computers. Post quantum cryography sometimes referred to as quantum proof, quantum safe or quantum resistant refers to cryographic algorithms usually public key algorithms that are thought to be secure against an at.tack by a quantum computer. As of 2019, this is not true for the most popular public key algorithms, which can be efficiently broken by a sufficiently strong quantum computer..1 Footnotes 1 http //In co.ntrast to the threat quantum computing poses to current public key algorithms, most current symmetric cryographic algorithms and hash functions are co.nsidered to be relatively secure against at.tacks by quantum computers.