HMAC support?

[ylxdzsw]

I use this package for the TOTP algorithm and some exchanges protocols. Both requires an HMAC functionality, so I hope this can be built into this package like Nettle.jl did.

The implementation (from wiki) can be quiet simple:

function hmac(key::Vector{UInt8}, msg::Vector{UInt8}, hash, blocksize::Int=64)
    if length(key) > blocksize
        key = hash(key)
    end

    pad = blocksize - length(key)

    if pad > 0
        resize!(key, blocksize)
        key[end-pad+1:end] = 0
    end

    o_key_pad = key .⊻ 0x5c
    i_key_pad = key .⊻ 0x36

    hash([o_key_pad; hash([i_key_pad; msg])])
end

and here is a test suite (also from wiki):

@test hmac(b"", b"", sha1, 64)   == hex2bytes("fbdb1d1b18aa6c08324b7d64b71fb76370690e1d")
@test hmac(b"", b"", sha256, 64) == hex2bytes("b613679a0814d9ec772f95d778c35fc5ff1697c493715653c6c712144292c5ad")
@test hmac(b"key", b"The quick brown fox jumps over the lazy dog", sha1, 64)   == hex2bytes("de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9")
@test hmac(b"key", b"The quick brown fox jumps over the lazy dog", sha256, 64) == hex2bytes("f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8")

When opening an issue, please ping @staticfloat since he does not receive emails automatically when new issues are created.

[staticfloat]

Hey, this is great @ylxdzsw, if you care to open a PR with this code and the tests, I will happily merge it. I wouldn't want to strip you of your authorship rights. :)

[ylxdzsw]

Hi, I just opened #45 with better interface than above demo, hope it helps.

[staticfloat]

Merged in #45