Editing HMAC (section)

==Definition==
This definition is taken from RFC 2104:

:<math>\begin{align}
  \operatorname{HMAC}(K, m) &= \operatorname{H}\Bigl(\bigl(K' \oplus opad\bigr) \parallel 
\operatorname{H} \bigl(\left(K' \oplus ipad\right) \parallel m\bigr)\Bigr) \\
                         K' &= \begin{cases}
                                 \operatorname{H}\left(K\right) & \text{if}\ K\text{ is larger than block size} \\
                                 K                              & \text{otherwise}
                                \end{cases}
\end{align}</math>

where
: <math>\operatorname{H}</math> is a cryptographic hash function.
: <math>m</math> is the message to be authenticated.
: <math>K</math> is the secret key.
: <math>K'</math> is a block-sized key derived from the secret key, ''K''; either by padding to the right with 0s up to the block size, or by hashing down to less than or equal to the block size first and then padding to the right with zeros.
: <math>\parallel</math> denotes [[concatenation]].
: <math>\oplus</math> denotes bitwise [[exclusive or]] (XOR).
: <math>opad</math> is the block-sized outer padding, consisting of repeated bytes valued 0x5c.
: <math>ipad</math> is the block-sized inner padding, consisting of repeated bytes valued 0x36.{{Ref RFC|2104|rsection=2}}

{| class="wikitable"
! [[Hash function]] <code>H</code>
! <code>b</code>, [[byte]]s
! <code>L</code>, [[byte]]s
|-
| [[MD5]] || 64 || 16
|-
| [[SHA-1]] || 64 || 20
|-
| [[SHA-2|SHA-224]] || 64 || 28
|-
| [[SHA-2|SHA-256]] || 64 || 32
|-
| [[SHA-2|SHA-512/224]] || 128 || 28
|-
| [[SHA-2|SHA-512/256]] || 128 || 32
|-
| [[SHA-2|SHA-384]] || 128 || 48
|-
| [[SHA-2|SHA-512]] || 128 || 64<ref>{{cite web |title=FIPS 180-2 with Change Notice 1 |url=https://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf |website=csrc.nist.gov}}</ref>
|-
| [[SHA-3|SHA3-224]] || 144 || 28
|-
| [[SHA-3|SHA3-256]] || 136 || 32
|-
| [[SHA-3|SHA3-384]] || 104 || 48
|-
| [[SHA-3|SHA3-512]] || 72 || 64<ref>{{Cite journal |last=Dworkin |first=Morris |date=4 August 2015 |title=SHA-3 Standard: Permutation-Based Hash and Extendable-Output Functions |url=https://www.nist.gov/publications/sha-3-standard-permutation-based-hash-and-extendable-output-functions |journal=[[Federal Information Processing Standards]] |via=NIST Publications}}</ref>
|-
| colspan=3 |<code>out = H(in)</code><br /><code>L = length(out)</code><br /><code>b = H's internal block length</code>{{Ref RFC|2104|rsection=2}}
|}