tor/changes/bug40078

  o Minor bugfix (crypto):
    - Disable the unused batch verification feature of ed25519-donna. Fixes
      bug 40078; bugfix on 0.2.6.1-alpha. Found by Henry de Valence.
Disable ed25519-donna's batch verification. Fixes bug 40078. As reported by hdevalence our batch verification logic can cause an assert crash. The assert happens because when the batch verification of ed25519-donna fails, the code in `ed25519_checksig_batch()` falls back to doing a single verification for each signature. The crash occurs because batch verification failed, but then all signatures individually verified just fine. That's because batch verification and single verification use a different equation which means that there are sigs that can pass single verification but fail batch verification. Fixing this would require modding ed25519-donna which is not in scope for this ticket, and will be soon deprecated in favor of arti and ed25519-dalek, so my branch instead removes batch verification. 2021-07-30 15:35:48 +02:00			`o Minor bugfix (crypto):`
			`- Disable the unused batch verification feature of ed25519-donna. Fixes`
			`bug 40078; bugfix on 0.2.6.1-alpha. Found by Henry de Valence.`