Information
RC4 is a widely-used stream cipher. It's used in popular protocols such as SSL and WEP. Although remarkable for its simplicity and speed, the algorithm's history doesn't inspire confidence in its security.
It was found that the first few bytes of the keystream were strongly non-random and leaked information about the key. This can be countered by dropping the first part of the keystream, as seen in RC4Drop.
How to use:
Firstly, input a key. This will be used in the algorithm to encrypt your plaintext. Alternatively, the generate key button will do so for you.
Then, input some plaintext; what you want to encrypt. An output will appear in the bottom boxes with the base64 and hexadecimal versions of your ciphertext along with execution time.
Conversely, to decrypt, simply add the base64 ciphertext into the top input box along with key to decrypt with.