Finding wood where you expected steel
Recently I have been restoring my 1977 MGB Roadster over the weekends. While removing the carpet I discovered a problem, there was wood underneath the carpet rather than steel.
From a strength point of view there is absolutely nothing wrong with a wooden floor. Most houses have wooden floors. The MGs of the 1950s had wooden floors when the left the factory. The problem is not the wooden floor itself, the problem is that I expected to find steel. The previous owner was clearly hiding something and when the wood panels were finally removed I found a rust problem that could have been serious if left much longer.
That in a nutshell is the problem that we are currently finding with the cryptographic digest function SHA-1. We keep finding wood where the design calls for steel. The defects found to date are not a major safety concern in themselves, the problem is what they say about the security of the design.
It may be possible to repair the car with a special purpose rust inhibiting epoxy paint. If the rust turns out to be too bad it will be necessary to have the old floors removed and new ones welded in place.
Similar options exist to fix SHA-1. In the short term the industry is switching to SHA-2 which is believed to be considerably stronger and offers 256 and 512 bit versions. In the longer term a replacement will be agreed. The good news is that there is no reason at this point to believe that SHA-1 is unsafe to drive.
