HomeSYNOPSIS
success = hash:update(data)
DESCRIPTION
The Core4 system includes a copy of mbed TLS.
This function feeds the string data to a one-way hash.
The object hash must have been properly initialized with a supported algorithm.
The result can be retrieved by calling hash:finish().
RETURN VALUE
On success, returns true.
On failure, returns nil, a string describing the error and the mbedtls error code number.