Encrypt and decrypt text with the SEED block cipher (KISA, RFC 4269) in CBC mode. Ciphertext is hex. Everything runs in your browser.
SEED is a 128-bit block cipher developed by the Korea Internet and Security Agency (KISA) and published as RFC 4269. It is mandated in much South Korean software, banking and government systems. This tool runs SEED-128 in CBC mode with PKCS padding; the same key and IV are needed to decrypt.
Encrypt and decrypt text with the SEED block cipher (KISA, RFC 4269) in CBC mode. Hex output. Runs entirely in your browser.
SEED is a 128-bit block cipher developed by the Korea Internet and Security Agency (KISA) in 1998 and standardised as RFC 4269. For years it was mandated for online banking, e-government and many other services in South Korea, so it still appears widely in Korean software. This tool encrypts and decrypts text with SEED-128 in CBC mode.
Input:
Plaintext + key (32 hex chars) + IV (32 hex chars)
Output:
hex ciphertext
What key size does SEED use?
SEED-128 uses a 128-bit (16-byte) key entered as 32 hexadecimal characters. Use the refresh button to generate a random key or IV.
Where is SEED used?
Extensively in South Korean banking, payment and government systems, and in some TLS cipher suites, which is why interoperating with those systems often needs SEED.
Is SEED secure?
SEED has no known practical break and is an ISO/IEC and IETF standard, though AES is more common internationally. Use it when you need compatibility with SEED-based systems.
Does my data leave the browser?
No. Encryption and decryption run locally in your browser.