DES-EDE-OFB ENCRYPTION TOOL
Other Crypto Algorithms
AES-128-CBC AES-128-CBC-CTS AES-128-CBC-HMAC-SHA1 AES-128-CBC-HMAC-SHA256 AES-128-CCM AES-128-CFB AES-128-CFB1 AES-128-CFB8 AES-128-CTR AES-128-ECB AES-128-GCM AES-128-GCM-SIV AES-128-OCB AES-128-OFB AES-128-SIV AES-128-WRAP AES-128-WRAP-INV AES-128-WRAP-PAD AES-128-WRAP-PAD-INV AES-128-XTS AES-192-CBC AES-192-CBC-CTS AES-192-CCM AES-192-CFB AES-192-CFB1 AES-192-CFB8 AES-192-CTR AES-192-ECB AES-192-GCM AES-192-GCM-SIV AES-192-OCB AES-192-OFB AES-192-SIV AES-192-WRAP AES-192-WRAP-INV AES-192-WRAP-PAD AES-192-WRAP-PAD-INV AES-256-CBC AES-256-CBC-CTS AES-256-CBC-HMAC-SHA1 AES-256-CBC-HMAC-SHA256 AES-256-CCM AES-256-CFB AES-256-CFB1 AES-256-CFB8 AES-256-CTR AES-256-ECB AES-256-GCM AES-256-GCM-SIV AES-256-OCB AES-256-OFB AES-256-SIV AES-256-WRAP AES-256-WRAP-INV AES-256-WRAP-PAD AES-256-WRAP-PAD-INV AES-256-XTS ARIA-128-CBC ARIA-128-CCM ARIA-128-CFB ARIA-128-CFB1 ARIA-128-CFB8 ARIA-128-CTR ARIA-128-ECB ARIA-128-GCM ARIA-128-OFB ARIA-192-CBC ARIA-192-CCM ARIA-192-CFB ARIA-192-CFB1 ARIA-192-CFB8 ARIA-192-CTR ARIA-192-ECB ARIA-192-GCM ARIA-192-OFB ARIA-256-CBC ARIA-256-CCM ARIA-256-CFB ARIA-256-CFB1 ARIA-256-CFB8 ARIA-256-CTR ARIA-256-ECB ARIA-256-GCM ARIA-256-OFB CAMELLIA-128-CBC CAMELLIA-128-CBC-CTS CAMELLIA-128-CFB CAMELLIA-128-CFB1 CAMELLIA-128-CFB8 CAMELLIA-128-CTR CAMELLIA-128-ECB CAMELLIA-128-OFB CAMELLIA-192-CBC CAMELLIA-192-CBC-CTS CAMELLIA-192-CFB CAMELLIA-192-CFB1 CAMELLIA-192-CFB8 CAMELLIA-192-CTR CAMELLIA-192-ECB CAMELLIA-192-OFB CAMELLIA-256-CBC CAMELLIA-256-CBC-CTS CAMELLIA-256-CFB CAMELLIA-256-CFB1 CAMELLIA-256-CFB8 CAMELLIA-256-CTR CAMELLIA-256-ECB CAMELLIA-256-OFB CHACHA20 CHACHA20-POLY1305 DES-EDE-CBC DES-EDE-CFB DES-EDE-ECB DES-EDE-OFB DES-EDE3-CBC DES-EDE3-CFB DES-EDE3-CFB1 DES-EDE3-CFB8 DES-EDE3-ECB DES-EDE3-OFB DES3-WRAPKey Structure
DES-EDE-OFB employs either two or three independent 56-bit DES keys, commonly referred to as K1, K2, and K3. When two keys are used, K1 and K3 are identical, whereas three distinct keys increase cryptographic strength. The total effective key length depends on the number of keys, ranging from 112 bits for two keys to 168 bits for three keys. The algorithm requires an initialization vector (IV) equal to the block size of DES, which is 64 bits, to initiate the output feedback process.
Encryption Process
Encryption begins by generating a key stream using the OFB mode. In this mode, the IV is first encrypted with K1, producing an output block. This block is then decrypted with K2 and encrypted again with K3 (for three-key configurations) or K1 (for two-key configurations), creating a keystream block. Each plaintext block is combined with the keystream using a bitwise exclusive OR (XOR) operation. The output feedback ensures that the same plaintext block encrypted multiple times with the same key and IV produces the same ciphertext block sequence, but subsequent blocks are linked through the feedback mechanism.
Decryption Process
Decryption mirrors the encryption sequence, as OFB mode converts the block cipher into a synchronous stream cipher. The keystream generated during decryption is identical to the encryption keystream if the IV and keys match. Ciphertext blocks are XORed with the keystream blocks to recover the original plaintext. This design allows error propagation to be minimal, affecting only the corresponding block in case of transmission errors.
Security Considerations
DES-EDE-OFB strengthens security against exhaustive key search attacks compared to single DES. The OFB mode prevents pattern repetition in ciphertext, which enhances resistance to certain cryptanalytic techniques. However, the algorithm relies on proper key management and IV selection to maintain confidentiality. Reusing an IV with the same key compromises security, as identical keystream blocks would expose correlations in the ciphertext.
Performance Characteristics
The algorithm supports parallel processing of keystream generation, improving efficiency in high-throughput systems. As a stream-oriented mode, OFB avoids padding overhead required in other block cipher modes, making it suitable for encrypting data of arbitrary length. DES-EDE-OFB also maintains backward compatibility with existing DES implementations by reusing the DES core functions without structural changes.
Applications
DES-EDE-OFB is employed in environments requiring strong encryption while maintaining compatibility with legacy DES systems. Its use spans secure communications, data storage, and cryptographic protocols where stream cipher behavior and minimized error propagation are advantageous.