Analog circuit for multiplying in the frequency domain
It is certainly possible to perform this 64-bit operation without a DSP -- a Boolean NAND of 64-bit OFDM values A and B, where each bit-position is encoded as a different frequency traveling along the same wire.

Off the top of my head, perhaps A goes into a filter bank (analog wavelet transform) that splits A into its 64 component frequencies (using a few dozen op-amps), and low-pass filters each component (a simple RC filter for each component).
(My understanding is that people have designed several chips that include single-chip filter banks designed to do low-power wavelet transforms a, b, c, d etc.).
B goes into a similar filter bank.
The filter banks feed 64 Schmitt-trigger NAND gates (16 chips of 74HC132).

The result could be re-encoded on an output signal C by connecting each NAND gate output to turn on or off a transistor connecting one end of a resistor to the appropriate oscillator.
(Presumably to generate A and B, you already have 64 oscillators, each one tuned to one of the desired bit-position frequencies).
All 64 resistors are connected together at the summing node of a single op-amp that transmits all 64 bits out a single copper trace.

(This answer is mainly posted to show it is possible without a DSP. I look forward to other answers that are much more clever than this one. Perhaps using bandwidth-division multiplexing and nonlinear optics; 64 tuned phase-locked loops or frequency-locked loops; or perhaps somehow adding some non-linear components to a superheterodyne frequency-shifting system).