How could I decrypt a file (encrypted with AES-128) using openssl ? I do not remember the passphrase I used to encrypt it, but I saved the key generated and used to encrypt my file. How could I use this key to decrypt my file ?
The quick answer is NO, you can not.
A detailed answer: On this official documentation, you can read:
When only the key is specified using the -K option, the IV must explicitly be defined. When a password is being specified using one of the other options, the IV is generated from this password.
IV stands for Initialization Vector. You can understand quickly how it is used with the combination of the key within CBC algorithm as shown on this figure: