Addition of SEED Cipher Suites to Transport Layer Security (TLS)
updated by
- rfc-8996 — Deprecating TLS 1.0 and TLS 1.1
Extracted elements (9)
SEED was designed to be efficiently implementable in hardware and software with restricted resources (mobile devices, smart cards), making it suitable for constrained environments while maintaining 128-bit security. It is a Korean national industrial standard (TTAS.KO-12.0004) widely deployed in South Korean e-commerce and financial PKI.
The security properties and usage patterns of these cipher suites follow the same model as the AES-CBC cipher suites defined in RFC 3268; implementers should refer to both RFC 2246 (TLS) and RFC 3268 (AES-TLS) for broader security guidance.
All six cipher suites use SEED in cipher block chaining (CBC) mode as the bulk cipher. SEED is a 128-bit block cipher with a 128-bit key size and 16-round Feistel structure.
All six cipher suites use SHA-1 in an HMAC construction for message authentication, as described in Section 5 of RFC 2246 (TLS 1.0).
Six new TLS cipher suites are defined using SEED-CBC with SHA-1 HMAC, assigned code points 0x00,0x96 through 0x00,0x9B: TLS_RSA_WITH_SEED_CBC_SHA, TLS_DH_DSS_WITH_SEED_CBC_SHA, TLS_DH_RSA_WITH_SEED_CBC_SHA, TLS_DHE_DSS_WITH_SEED_CBC_SHA, TLS_DHE_RSA_WITH_SEED_CBC_SHA, and TLS_DH_anon_WITH_SEED_CBC_SHA.
The cipher suites differ only in key exchange algorithm: RSA, DH_DSS, DH_RSA, DHE_DSS, DHE_RSA, and DH_anon, with semantics defined by TLS sections 7.4.2 and 7.4.3.
This document registers six new TLS cipher suite values (0x0096–0x009B) in the TLS Cipher Suite registry, each pairing SEED-CBC bulk encryption with SHA-1 HMAC and a distinct key exchange method.
SEED is considered no less secure than corresponding cipher suites; no security vulnerabilities have been found. It is robust against differential cryptanalysis, linear cryptanalysis, and related-key attacks, and has been evaluated as cryptographically secure by ISO/IEC JTC 1/SC 27 and Japan CRYPTREC.
Each cipher suite identifier is a 2-byte code point. The SEED cipher suites occupy the range { 0x00, 0x96 } through { 0x00, 0x9B } in the TLS cipher suite registry.