Blueprints

Calculator

Workflow

Completed tasks are crossed through

JavaScript	NaCl	Server
		Send page to browser
Render page	Render page
Obtain formula from user
Pass formula to NaCl
	Pre-process formula (using our FHE library) into boolean circuit + data
	Parse the formula and replace numbers with variables; encrypt numbers
	Base64-encode BigInts
	Translate internal structures into XML
Call returns XML-RPC-encoded circuit + data request from NaCl	Return XML-RPC-encoded circuit + data request to JS
Send the XML-RPC request to server		Receive XML-RPC boolean circuit + data
		Process it (using our FHE library)
Receive XML-RPC-encoded result		Return XML-RPC-encoded result
Pass XML-RPC-encoded result to NaCl	Receive XML-RPC-encoded result
	Decode XML-RPC-encoded result
Call returns the result	Return result to JS
Display result

Remarks:

• BigNums are represented in XML-RPC as big-endian 2-complement, base-64-encoded
• BigFloats are represented in XML-RPC as XXX, base-64-encoded
  Simple text input of a calculator, with a submit button, optional throbber which will spin while computation is in progress, and a result display. Optional formula + result history.

Mockup

1 + 1 = 2 ← [throbber] in place of result while calculation is in progress
[last formula & result]
[second last formula & result]
[third last formula & result]
…

FHE Library

Required Operations

§3.2 of Gentry (2010)

• Generate x-bit BigInt
• Add
• Multiply
• Modulo (as defined in the paper)
• Compile formula into boolean circuit comprised of AND and XOR gates

Possibly Useful Libraries

• GnuTLS
• Mozilla NSS
• GNU Multiple Precision Arithmetic Library — Would be nice to use a general-purpose mathematical library for the freedom to do arbitrary math, e.g. if future algorithms call for some esoteric operations
• Unfortunately can’t use libssl BIGNUM because its license is not GNU-GPL-compatible