6 ms·

Git was not intended (AFAIK) to be cryptographically secure. Being unsuitable for crypto != being unsuitable for other uses.

• wcoenen 5y ago
  Surely signed tags and signed commits in git are supposed to be cryptographically secure? [0] Doesn't the security of those signatures depend on the security of the SHA-1 hashes that are being signed? [0] https://git-scm.com/book/en/v2/Git-Tools-Signing-Your-Work https://git-scm.com/book/en/v2/Git-Tools-Signing-Your-Work
  • danachow 5y ago
    No - after all, the most common use of digital signatures is to sign documents that can be easily tampered. All the security is in the signature, not the content being signed.
    • lvh 5y ago
      This makes no sense. Sure: you can generate an X.509 certificate that says whatever you want, but the point is that you can validate the signature and see that it's a forgery. In the case of a hash-addressed system like git, the problem is that the signature is over a collision, so it no longer certifies the thing its supposed to certify. Git uses the hash as a shorthand for a revision, including its entire history--so yes, it is using the hash that way. By that logic, would MD5 be fine? MD4? CRC32?
    • wongarsu 5y ago
      A digital signature usually signs (~encrypts) a hash of the content. So asking what exactly signing a commit or tag entails is a very valid question. I would expect that signing a tag is only as strong as SHA-1, since a tag is essentially a label for a commit hash. For signing commits I have no clue, but would be quite interested as well.