The Keyed-Hash Message Authentication Code (HMAC) (FIPS-198 ...

More documents

Recommendations

Info

Figure 1: Illustration of the HMAC Construction6. IMPLEMENTATION NOTEThe HMAC algorithm is specified for an arbitrary Approved cryptographic hash function,H. With minor modifications, an HMAC implementation can easily replace one hashfunction, H, with another hash function, H’.Conceptually, the intermediate results of the compression function on the B-byte blocks(K 0 ⊕ ipad) and (K 0 ⊕ opad) can be precomputed once, at the time of generation of the5
key K, or before its first use. These intermediate results can be stored and then used toinitialize H each time that a message needs to be authenticated using the same key. Foreach authenticated message using the key K, this method saves the application of the hashfunction of H on two B-byte blocks (i.e., on (K ⊕ ipad) and (K ⊕ opad)). This savingmay be significant when authenticating short streams of data. These storedintermediate values shall be treated and protected in the same manner as secretkeys.Choosing to implement HMAC in this manner has no effect on interoperability.Object identifiers (OIDs) for HMAC are posted at http://csrc.nist.gov/csor, along withprocedures for adding new OIDs.6
Page 1 and 2: FIPS PUB 198FEDERAL INFORMATION PRO
Page 3 and 4: Federal Information Processing Stan
Page 5 and 6: 12. Qualifications. The security af
Page 7: Federal Information Processing Stan
Page 10 and 11: K 0Lopadttextx’N’bits.The key K
Page 14 and 15: APPENDIX A: HMAC EXAMPLESThese exam
Page 16 and 17: K 0 ⊕ opad:6c6d6e6f 68696a6b 6465
Page 18 and 19: a0K 0 : 70717273 74757677 78797a7b
Page 20: APPENDIX C: REFERENCES[1] American

The Keyed-Hash Message Authentication Code (HMAC) (FIPS-198 ...

Create successful ePaper yourself

Delete template?

Save as template?