Cryptographic Counters and Applications to Electronic Voting

We formalize the notion of a cryptographic counter, which allows a group of participants to increment and decrement a cryptographic representation of a (hidden) numerical value privately and robustly. The value of the counter can only be determined by a trusted authority (or group of authorities, which may include participants themselves), and participants cannot determine any information about the increment/decrement operations performed by other parties. Previous efficient implementations of such counters have relied on fullyhomomorphic encryption schemes; this is a relatively strong requirement which not all encryption schemes satisfy. We provide an alternate approach, starting with any encryption scheme homomorphic over the additive group Z2 (i.e., 1-bit xor). As our main result, we show a general and efficient reduction from any such encryption scheme to a general cryptographic counter. Our main reduction does not use additional assumptions, is efficient, and gives a novel impleme...

• Type: Conference
• Year: 2001
• Where: EUROCRYPT
• Authors: Jonathan Katz, Steven Myers, Rafail Ostrovsky
• Keywords: Cryptographic Counter, Cryptology, Encryption Scheme, EUROCRYPT 2001, General Cryptographic Counter