Robust MAC aggregation with short MAC tags

An apparatus for producing an aggregated message authentication code (MAC), comprising:

• a computer processor that is programmed to generate or to receive a first message and its first MAC tag (m1, t1), and a second message and its second MAC tag (m2, t2), wherein:
• the computer processor is programmed to compute a first hashed message-tag pair H(m1, t1), and a second hashed message-tag pair H(m2, t2) where H is a cryptographic hash function;
• and
• the computer processor is programmed to compute a first aggregated MAC (At1) by an addition operation, as follows:
• At1=(H(m1,t1)+H(m2,t2))modulo N,
• where N is a natural number selected to equal to two or greater.

A non-transitory computer readable medium, comprising:

• computer-executable instructions stored on the computer readable medium that, when executed by a computer processor, perform a method that includes computing an aggregated message authentication code (MAC), including:
• generating or receiving, in the computer processor, a first message and its first MAC tag (m1, t1)
• computing, in the computer processor, a first hashed message-tag pair H(m1, t1), where H is a cryptographic hash function;
• generating or receiving, in the computer processor, a second message and its second MAC tag (m2 t2);
• computing, in the computer processor, a second hashed message-tag pair H(m2, t2);
• computing, in the computer processor, an aggregated MAC (At1) by an addition operation, as follows:
• At1=(H(m1,t1)+H(m2,t2))modulo N,
• where N is selected to equal a natural number equal to two or greater.