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Speaker:ChungYi Wang Advister:Quincy Wu 2007/4/23

RFC 4835 - Cryptographic Algorithm Implementation Requirements for Encapsulating Security Payload (ESP) and Authentication Header (AH). Speaker:ChungYi Wang Advister:Quincy Wu 2007/4/23. Outline. Motivation ESP & AH ESP & AH table Changes from RFC 2402 and RFC 2406 to RFC 4305

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Speaker:ChungYi Wang Advister:Quincy Wu 2007/4/23

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  1. RFC 4835 - Cryptographic Algorithm Implementation Requirements for Encapsulating Security Payload (ESP) and Authentication Header (AH) Speaker:ChungYi Wang Advister:Quincy Wu 2007/4/23

  2. Outline • Motivation • ESP & AH • ESP & AH table • Changes from RFC 2402 and RFC 2406 to RFC 4305 • Changes from RFC 4305 • Reference

  3. Motivation • The IPsec series of protocols makes use of various cryptographic algorithms in order to provide security services. • To ensure interoperability between disparate implementations, it is necessary to specify a set of mandatory-to- implement algorithms to ensure that there is at least one algorithm that all implementations will have available.

  4. ESP & AH(1/3) • Encapsulating Security Payload (ESP) • 內容保密 • Authentication Header (AH) • 身分認證，重送確認

  5. ESP & AH(2/3) • AH http://en.wikipedia.org/wiki/IPsec#Encapsulated_Security_Payload_.28ESP.29 IP address, key … Integrity Check Value

  6. ESP & AH(3/3) • ESP http://en.wikipedia.org/wiki/IPsec#Encapsulated_Security_Payload_.28ESP.29

  7. ESP & AH table(1/7)

  8. ESP & AH table(2/7) • SHOULD+ • 未來可能變成MUST • SHOULD- • 未來可能變成MAY • MUST- • 未來可能不再是MUST

  9. ESP & AH table - DES(3/7) • DES (Data Encryption Standard) • small key size(56bits), publicly demonstrated, open-design special-purpose cracking hardware Questionable security for general use • TripleDES • Key size:168 bits • Rounds:48 DES-equivalent rounds http://en.wikipedia.org/wiki/TripleDES

  10. ESP & AH table - AES(4/7) • AES (Advanced Encryption Standard) • NIST 宣佈，於1998 第一次提出，也就是Rijndael • Key Size:128bits, 192bits, 256bits • Block size:128bits • 於軟體和硬體上的運算都很快, 容易實作, 並且不需要太多的記憶體操作。

  11. ESP & AH table - HMAC(5/7) • HMAC (keyed-hash message authentication code) • 利用雜湊函式進行 身分驗證，資料完整性的演算法。 • MD5 • Digest size:128bits • Rounds:4 • SHA-1 • Digest size:128bits • Rounds:80

  12. ESP & AH table - Collision(6/7) • H(x) = H(y) • X 不等於 y • 不同來源卻有相同的認證hash • 如果很不容易找到ㄧ對 x, y， 符合 H(x) = H(y)，就是一個強壯的(strong)雜湊函式演算法。

  13. ESP & AH table(7/7)

  14. Changes from RFC 2402 and RFC 2406 to RFC 4305

  15. Changes from RFC 4305

  16. Reference • RFC 4835 • http://www.faqs.org/rfc/rfc4835.txt • IPsec (ESP & AH) • http://en.wikipedia.org/wiki/IPsec#Encapsulated_Security_Payload_.28ESP.29 • DES • http://en.wikipedia.org/wiki/Data_Encryption_Standard • AES • http://en.wikipedia.org/wiki/Advanced_Encryption_Standard • NIST:http://www.commerce.gov/opa/photo/NIST/events.html

  17. Reference • HMAC • http://en.wikipedia.org/wiki/HMAC • Hash collision : http://en.wikipedia.org/wiki/Hash_collision • MD5 • http://en.wikipedia.org/wiki/MD5 • SHA1 • http://en.wikipedia.org/wiki/SHA

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