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--- pgpfan:agevspgp [2021/12/28 18:31] – [Data Recovery] Single flipped bit. b.walzer
+++ pgpfan:agevspgp [2021/12/30 23:01] (current) – [File Substitution] Typo. b.walzer
@@ Line 44: / Line 44: @@
 To be clear, "recovery" here is the sifting of good data from bad. Neither age or GnuPG can regenerate good data from redundant bad data.
-Here is what this would look like in practice using the example of a single flipped bit((Please note that the single flipped bit here is not a realistic example and that in practice damage tends to encompass one or more media blocks. Such blocks tend to be multiples of 512 bytes.)) near the start of the encrypted file. First age:
+Here is what this would look like in practice using the example of a single flipped bit((Please note that the single flipped bit here is not a realistic example and that in practice damage tends to encompass one or more media blocks. Such blocks tend to be multiples of 512 bytes. Often the blocks are entirely missing.)) near the start of the encrypted file. First age:
   $ age -d -i key.txt -o totc_out.txt totc.txt.age
@@ Line 82: / Line 82: @@
 At this point you might want to consider how often longer term backups end up with bad sections. Then consider how many attackers exist with sufficient skill, combined with sufficient knowledge of the organization and content of your backups to do reliable changes. Attackers that are willing to have their efforts revealed after the first attempt. This would seem to be where OpenPGP is superior to age.
+The ultimate point here is that "blowing up with an error" might not be the best way to handle this sort of situation in a command line utility. A lesson from application programming is that it is often better to complete the operation and return the error at the end.
 ====File Substitution====
-Public key encryption has a generic consideration that is quite relevant here. Anyone with access to the public key can easily create a file that will pass any file modification tests ... because after all //that// file has not been modified after creation. You can try to keep the public key secret but a public key design does not guarantee thatthe public key can not be derived from the encrypted material. That guarantee only applies to the secret key. So an attacker can skip the bother of attempting to overcome the authentication and just replace the file with whatever they want.
+Public key encryption has a generic consideration that is quite relevant here. Anyone with access to the public key can easily create a file that will pass any file modification tests ... because after all //that// file has not been modified after creation. You can try to keep the public key secret but a public key design does not guarantee that the public key can not be derived from the encrypted material. That guarantee only applies to the secret key. So an attacker can skip the bother of attempting to overcome the authentication and just replace the file with whatever they want.
 The traditional fix for this weakness is to cryptographically sign the file ... and, once again, age does not do signatures. An age user would need to go through the process of finding a separate signing utility and would have to apply it correctly while using a separate signature file. A GnuPG user would only have to add a ''%%-s%%'' option while encrypting and would have an integrated signature protected by the encryption. No further effort would be required on the part of the GnuPG user. A good signature message would appear automatically after decryption.