I've seen a lot of ciphers with variants that use 80-bit keys, like Grain, Trivium, KLEIN, KATAN & KTANTAN, Piccolo, PRESENT, RC4, Skipjack, and TWINE. Some of these designs are younger than six years old, making me wonder if an 80-bit key size is "secure", be it against brute force attacks or as a buffer in the case of weaknesses in a cipher's design. Is 80-bit security not enough anymore? Is it only on the edge of being insecure? If it is on the edge, by what time will 80-bit keys be obsolete?