UMACVMAC

UMACVMAC is a cryptographic construction that aims to provide a fast, secure message authentication code by combining two established MAC families: UMAC (Universal MAC) and VMAC (Vector MAC). The design seeks to leverage UMAC’s universal hashing approach together with VMAC’s efficient finalization to achieve high-throughput authentication suitable for modern networking and data processing environments.

Construction and operation involve two independent keys: Ku for UMAC and Kv for VMAC. For a given message m, the scheme computes t1 = UMAC_Ku(m) and t2 = VMAC_Kv(m). The final authentication tag t is formed by combining t1 and t2, commonly through an XOR or by concatenating and then truncating to a desired tag length. The verification process recomputes the two intermediate tags on the received message and checks that the final tag matches the expected value. This dual-stage approach is designed to preserve the simplicity of MAC verification while enabling flexible tag lengths.

Security considerations for UMACVMAC rely on the UF-CMA security of both constituent MACs and the assumption that the two computations are independent. If UMAC_Ku and VMAC_Kv each provide established UF-CMA security for their respective tag lengths, and the combination function does not introduce leakage, the overall construction aims to resist forgery under chosen-message attacks up to the respective security bounds. In practice, security proofs are sensitive to the exact combining method and parameter choices, including tag length and key management.

Performance and implementation notes indicate that UMACVMAC is most suitable for environments where both UMAC and VMAC are already optimized. It requires managing two keys and performing two MAC computations per message, with potential savings achievable through parallel or vectorized hardware support. This construction remains primarily of interest in academic discussions and niche applications rather than standardization efforts. See also UMAC and VMAC.