Cryptography & Ciphers
RC2 Decryption
Decrypt RC2 ciphertext with its key and IV. A blank IV selects ECB, an 8-byte IV selects CBC, and PKCS#7 padding is checked.
This tool runs open-source code from CyberChef by GCHQ (Apache License 2.0). See open-source credits.
A blank IV selects ECB; an IV selects CBC. The engine checks PKCS#7 padding before returning plaintext.
Raw output uses one character per byte. Hex output retains an explicit representation of binary plaintext.
- Read RC2-encrypted records from a legacy system during an authorized migration.
Match the key, IV, and ciphertext encoding
- Paste ciphertext and choose Input format.
- Enter the key and its Key format.
- Supply the original IV for CBC, then choose Output format.
Recover a known RC2 message
Input: 799ba7666fa19bb3a3a6eb8c11f37f05
Settings: Key format Hex, Key 0011223344556677, IV format Hex, IV 0102030405060708, Input Hex, and Output Raw.
Result: Hello RC2
RC2 Decryption receives 16 bytes, which is two 8-byte blocks. Hello RC2 is 9 bytes, so the second block ends with 7 bytes of PKCS#7 padding. Output Hex shows 48656c6c6f20524332.
Effective key bits and padding errors
- The engine uses 128 effective key bits; other effective key lengths need another implementation.
- RC2 provides no authentication.
- Use RC2 for existing data, not new protection.