crypto.fromHex feature request

[georeb]

Missing feature

crypto.fromHex

The missing counterpart to crypto.toHex

Provides an ASCII char representation of a (hex) Lua string. Each hex byte in the input string is represented as two hex characters.

For example: "48656c6c6f576f726c64"

Justification

The use of encrypt and decrypt is for purposes where the original value is required at a later date. Using toHex is very useful, but when this is later required, the hex data string must be converted back into the original char string.

Workarounds

Currently using this code:

--First encrypt the data

    local output = crypto.toHex(crypto.encrypt("AES-ECB","mykey","data"))

--Then decrypt the data WITHOUT the use of 'crypto.fromHex'

    local input

    for i=1, #output, 2 do
        if not input then
            input=string.char("0x"..string.sub(output,i,i+1))
        else
            input=input..string.char("0x"..string.sub(output,i,i+1))
        end
    end

    return crypto.decrypt("AES-ECB", "mykey", input):match("(.-)%z*$")

--Or decrypt the data WITH the use of 'crypto.fromHex'

    local input = crypto.fromHex(output)

    return crypto.decrypt("AES-ECB", "mykey", input):match("(.-)%z*$")

[nwf]

I think we should get deprecate then remove crypto.toHex and crypto.toBase64 and redirect to the encoder module (https://nodemcu.readthedocs.io/en/master/modules/encoder/), which provides the inverse functions as well.

[georeb]

Didn't spot the encoder.fromHex function. Thanks!