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Perform RC4 stream cipher encryption and decryption online. Supports direct text input and secret key management.
Enter content and click Encrypt/Decrypt button
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When you need to quickly test or understand the RC4 stream cipher mechanism, this tool provides instant encryption and decryption capabilities. RC4 (Rivest Cipher 4) is a symmetric stream cipher algorithm. It initializes a state vector through the Key-Scheduling Algorithm (KSA), outputs a keystream via the Pseudo-Random Generation Algorithm (PRGA), and finally achieves data encryption or decryption through an XOR operation. It processes byte streams; after entering the text and secret key, it outputs the corresponding ciphertext (in hexadecimal) or the original plaintext.
Is the RC4 algorithm secure?
No. RC4 has vulnerabilities such as initial byte biases and is no longer recommended for high-security scenarios.
What are the input and output format requirements?
All inputs are converted to byte streams using UTF-8 encoding. The encrypted output is a hexadecimal string (e.g., 48656c6c6f), and the decrypted output is restored to the original text. Example: Inputting "Hello" with the key "key" outputs "726f661c" after encryption.
The secret key must remain identical for successful decryption. Avoid using short keys (≥16 characters recommended). Please switch to AES when handling sensitive data. Your browser environment may limit the processing of extremely large texts.
For educational purposes, we recommend comparing RC4 with AES in CTR mode: under the same key, the first 1024 bytes of RC4 should be discarded to mitigate biases, whereas AES-CTR requires ensuring nonce uniqueness. Typical test case: Plaintext="Test123", Key="secret", RC4 Ciphertext="a4d33e8b26".
