SEED Encryption/Decryption
Korean Standard 128-bit Block Cipher (KISA)
Algorithm Information
Note: SEED uses fixed 128-bit key (unlike AES which supports 128/192/256)
Note: Supports ECB, CBC, CFB, and OFB modes
About SEED Cipher
SEED is a symmetric block cipher developed by Korea Information Security Agency (KISA) in 1998. It was adopted as a Korean national standard (TTA standard) and later recognized internationally as ISO/IEC 18033-3 and RFC 4269.
| Algorithm | SEED |
| Standard | KISA / ISO 18033-3 / RFC 4269 |
| Key Size | 128 bits (fixed) |
| Block Size | 128 bits |
| Rounds | 16 |
| Mode | ECB / CBC / CFB / OFB |
| Padding | PKCS7 / Zero / ISO10126 / ANSI X.923 / None |
| Origin | Korea (KISA) |
| Year | 1998 |
Key Features
- 128-bit fixed key length - simple and secure
- 128-bit block size - same as AES
- 16-round Feistel network structure
- Modified Feistel structure with two 64-bit halves
- Resistant to known cryptanalytic attacks
Common Use Cases
Security Considerations
- SEED has undergone extensive cryptanalysis and is considered secure
- Always use random, unpredictable keys and IVs
- Never reuse the same Key-IV combination
- CBC mode requires proper padding handling
- Consider ARIA or AES for new international applications
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