Security Articles from Wikipedia

Certificate authority 27
References
[1] https:/ / spreadsheets. google. com/ pub?key=ttwCVzDVuWzZYaDosdU6e3w& single=true& gid=0& output=html, List of Trusted Root
Certificate Authorities, 2/10/2010.
[2] http:/ / www. defcon. org/ images/ defcon-17/ dc-17-presentations/ defcon-17-zusman-hacking_pki. pdf
[3] Verisign, Inc. (31 January 2001). "Jan 2001 - Advisory from VeriSign, Inc." (http:/ / www. verisign. com/ support/ advisories/
authenticodefraud. html). . Retrieved 2008-12-02.
[4] Microsoft, Inc. (February 21, 2007). "Microsoft Security Bulletin MS01-017: Erroneous VeriSign-Issued Digital Certificates Pose Spoofing
Hazard" (http:/ / support. microsoft. com/ kb/ 293818). . Retrieved 2011-Nov-09.
[5] Bright, Peter (28 March 2011). "Independent Iranian hacker claims responsibility for Comodo hack" (http:/ / arstechnica. com/ security/ news/
2011/ 03/ independent-iranian-hacker-claims-responsibility-for-comodo-hack. ars). Ars Technica. . Retrieved 1 September 2011.
[6] Bright, Peter (30 August 2011). "Another fraudulent certificate raises the same old questions about certificate authorities" (http:/ / arstechnica.
com/ security/ news/ 2011/ 08/ earlier-this-year-an-iranian. ars). Ars Technica. . Retrieved 1 September 2011.
[7] Fraudulent DigiNotar Certificate Usage (http:/ / www. theregister. co. uk/ 2011/ 09/ 06/ diginotar_audit_damning_fail/ ) Retrieved 7
September 2011.
[8] http:/ / www. abanet. org/ rppt/ meetings_cle/ 2002/ 2002spring/ RealProperty/ Thursday/ TechnologyandtheRealEstate/
OnlineTransactionManagement. pdf
[9] http:/ / www. webtrust. org/
[10] http:/ / news. netcraft. com/ ssl-sample-report/ CMatch/ certs
[11] http:/ / pki. fedoraproject. org/ wiki/ PKI_Main_Page
[12] http:/ / xca. hohnstaedt. de
External links
• Certificate authorities (http:/ / www. dmoz. org/ Computers/ Security/ Public_Key_Infrastructure/ PKIX/
Tools_and_Services/ Third_Party_Certificate_Authorities/ / ) at the Open Directory Project
• Certificate Authority Reviews (http:/ / www. sslshopper. com/ certificate-authority-reviews. html)
• Certificate Authorities by Country (http:/ / www. tractis. com/ countries)
CMAC
In cryptography, CMAC (Cipher-based MAC) SP800-38B is a block cipher-based message authentication code
algorithm. It may be used to provide assurance of the authenticity and, hence, the integrity of binary data. This mode
of operation fixes security deficiencies of CBC-MAC (CBC-MAC is secure only for fixed-length messages).
The core of the CMAC algorithm is a variation of CBC-MAC that Black and Rogaway proposed and analyzed under
the name XCBC BR2 and submitted to NIST. BR1 The XCBC algorithm efficiently addresses the security deficiencies
of CBC-MAC, but requires three keys. Iwata and Kurosawa proposed an improvement of XCBC and named the
resulting algorithm One-Key CBC-MAC (OMAC) in their papers. IK2IK1 They later submitted OMAC1 IK3 , a
refinement of OMAC, and additional security analysis. IK4 The OMAC algorithm reduces the amount of key material
required for XCBC. CMAC is equivalent to OMAC1.
To generate an ℓ-bit CMAC tag (t) of a message (m) using a b-bit block cipher (E) and a secret key (k), one first
generates two b-bit sub-keys (k 1 and k 2 ) using the following algorithm (this is equivalent to multiplication by x and
x 2 in a finite field GF(2 b )). Let ≪ signify a standard left-shift operator:
1. Calculate a temporary value k 0 = E k (0).
2. If msb(k 0 ) = 0, then k 1 = k 0 ≪ 1, else k 1 = (k 0 ≪ 1) ⊕ C; where C is a certain constant that depends only on b.
(Specifically, C is the non-leading coefficients of the lexicographically first irreducible degree-b binary
polynomial with the minimal number of ones.)
3. If msb(k 1 ) = 0, then k 2 = k 1 ≪ 1, else k 2 = (k 1 ≪ 1) ⊕ C.
As a small example, suppose b = 4, C = 0011 2 , and k 0 = E k (0) = 0101 2 . Then k 1 = 1010 2 and k 2 = 0100 ⊕ 0011 =
0111 2 .