Small signature for packets using asymetric encryption? The smallest signature sizes that I can find are for elliptic curve public key systems where the signature is 4 times the security level (2 x the key size). In my case I can change the key every day, after which it is OK if the key is revealed. 

So my questions are: 


is there a more efficient signature than 2 x key size?
what would be the minimal acceptable key size for implementations over the next 10 years or so. Looking at a table of key size vs. operations to crack I get a 108 bit ECC key requires 1.8 x 10^8 MIPS, but I'm not sure how to interpret MIPS these days when graphics processors are so powerful. Is 1.8 x 10^8 MIPS a lot of compute power?
A Signature-Scheme known for it's short signatures is the Boneh-Lynn-Shacham (BLS) Signature Scheme, that uses not only Elliptic Curves but Bilinear Pairings over the curve.
The paper can be found here and lists signature sizes provided. For example the paper states that you can 


  … get a signature of length 154 bits with security comparable to 320-bit DSA or 320-bit ECDSA …