hmac?

[PA <petite.abeille@...>]

Hello,

Does anyone have a little Lua module to compute a keyed-hash message 
authentication code (e.g. HMAC-MD5)?

Here is what I have so far, which uses Luiz Henrique de Figueiredo's 
lmd5 [1] and Reuben Thomas's bitlib [2]:

function hmac( aKey, aValue )
        if aKey:len() > 64 then
                aKey = md5.digest( aKey, true )
        end

        if aKey:len() < 64 then
                aKey = aKey .. string.char( 0 ):rep( 64 - aKey:len() )
        end

        local anInnerKey = aKey:gsub( ".", function( aChar ) return 
string.char( bit.bxor( aChar:byte(), 54 ) ) end )
        local anOuterKey = aKey:gsub( ".", function( aChar ) return 
string.char( bit.bxor( aChar:byte(), 92 ) ) end )
        local aDigest = md5.digest( anOuterKey .. md5.digest( 
anInnerKey .. aValue, true ) )

        return aDigest
end

print( hmac( "Jefe", "what do ya want for nothing?" ) )

> 750c783e6ab0b503eaa86e310a5db738

TIA.

Cheers

--
PA, Onnay Equitursay
http://alt.textdrive.com/

[1] http://www.tecgraf.puc-rio.br/~lhf/ftp/lua/#lmd5
[2] http://rrt.sc3d.org/Software/Lua/?page=Software/Lua