DES Decryption

DES decryption online

DES decryption reverses the legacy 64-bit block cipher using the same effective 56-bit key and compatible parameters. NIST withdrew DES in 2005 because its security was no longer adequate. Use this page for compatible legacy ciphertext, not for designing a new encryption system.

How to use this tool

Paste Hex or Base64 ciphertext, or choose a local file. Select the original mode and padding, then enter the exact key and IV. If the data used a KDF-derived key, reproduce its secret input, derivation function, hash, salt, and related KDF settings. Decrypt and view or download the recovered bytes.

Matching cipher parameters

Parameters must match those used by the source implementation or DES encryption. Hex and Base64 describe how ciphertext bytes are written, while the output encoding controls how recovered text is displayed. Salt is KDF input material; it is not the IV used by a cipher mode.

The standalone PBKDF2, EvpKDF, and HKDF tools can help compare derived bytes, but DES decryption still requires the final key, IV, mode, and padding to match.

Security warning

DES is obsolete and should not protect new data; prefer AES decryption for compatible modern systems. DES also supplies no authentication, so plausible output does not prove the ciphertext was unchanged. Avoid processing production secrets on an untrusted device or browser.

Frequently asked questions

Why can I not recover the original plaintext?

Compare the mode, padding, key bytes, IV, ciphertext encoding, and expected plaintext encoding. For KDF-derived keys, also match the secret input, derivation function, hash, salt, and KDF-specific settings such as iterations or info.

Does encryption detect tampering?

No. A wrong key or modified ciphertext can produce an error or meaningless bytes, but neither outcome is a dependable integrity check. Authentication must be provided separately by the original format or protocol.