271–280 of 433 posts
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Only if the defendant doesn't challenge the evidence. If I'm the defendant and I know I sent those emails, I'm not going to challenge the screenshot. If I know I did not send those emails, then I'll do my best to pay for forensic analysts to generate evidence to exonerate me.
Experts are expensive. Most defendants never get them.
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People might be assuming that 2048-bits is only twice as strong as 1024-bits, but it's in fact a billion times better. (corrected, thanks!)
That would be true if RSA scaled proportionally with the number of bits, but the exponent involved is much lower than 1. 1024->2048 gives you around the same difficulty as adding 30 bits to a symmetric key.
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I absolutely believe you - lawyers, judges, and juries alike tend to be technologically illiterate, but do you have any references/links to this happening?
If you read the blog post, you'll see that newspapers frequently verify DKIM signatures on stolen email corpora before they publish about them. Eg: https://www.propublica.org/nerds/authenticating-email-using-...
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Meanwhile in the real world, screenshots of emails without any cryptographic authentication at all are good enough to send people to prison.
The issue here isn't rules of evidence, it's user privacy. In the real world, DKIM has repeatedly been used to violate privacy. More importantly: latent verifiable secure DKIM signatures on archived emails offer no value to users; they literally only have real-world value to attackers.
I don't think this is quite true. First of all, this is not only valuable to attackers, it's also valuable in a court of law to establish the truth of what happened. Secondly, it can be valuable to me to be able to prove that you sent me an email, even if you wished to deny it, also mostly in legal contexts.
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The issue here isn't rules of evidence, it's user privacy. In the real world, DKIM has repeatedly been used to violate privacy. More importantly: latent verifiable secure DKIM signatures on archived emails offer no value to users; they literally only have real-world value to attackers.
> More importantly: latent verifiable secure DKIM signatures on archived emails offer no value to users; they literally only have real-world value to attackers. I don't think this is quite true. First of all, this is not only valuable to attackers, it's also valuable in a court of law to establish the truth of what happened. Secondly, it can be valuable to me to be able to prove that you sent me an email, even if you…
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No. DKIM is meant to apply to emails in transit; it is part of the transaction of exchanging emails. But DKIM signatures are verifiable long after that transaction has completed. That was not an intended feature of DKIM, and it's a grave privacy violation. To satisfy DKIM's design goal, you only need a "current" DKIM key that is secure for a window of time. When that window of time passes, you rotate the secret and p…
> it's a grave privacy violation. I'm missing something here. DKIM mostly proves an email from person@from.me was sent by a server @from.me controls. There is also a bloody great audit trail inside of the email with together with SPF can do a pretty good job of proving the same thing. I'm struggling to see how an email sent to me, that presumably was always intended to be readable by me could suddenly become a privac…
It comes down to if a third party gets access to your emails (e.g. through a server compromise), should they be able to prove to a fourth party that the emails are legitimately yours, vs completely faked? Non repudiation through strong DKIM keys enables this.
Example: Third party is a ransomware gang who releases your emails because you didn't pay a ransom after your email server was compromised. Fourth party is a journalist who doesn't trust the ransomware gang, but also wants to publish juicy stories about your company if there is one, but doesn't want to risk their reputation / a defamation case if the ransomware gang just invented the emails.
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> it's a grave privacy violation. I'm missing something here. DKIM mostly proves an email from person@from.me was sent by a server @from.me controls. There is also a bloody great audit trail inside of the email with together with SPF can do a pretty good job of proving the same thing. I'm struggling to see how an email sent to me, that presumably was always intended to be readable by me could suddenly become a privac…
I'm not sure privacy violation is necessarily the right term to help people understand why long-term non repudiation is an undesirable property for some people. It comes down to if a third party gets access to your emails (e.g. through a server compromise), should they be able to prove to a fourth party that the emails are legitimately yours, vs completely faked? Non repudiation through strong DKIM keys enables this.…
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People might be assuming that 2048-bits is only twice as strong as 1024-bits, but it's in fact a billion times better. (corrected, thanks!)
That would be true if RSA scaled proportionally with the number of bits, but the exponent involved is much lower than 1. 1024->2048 gives you around the same difficulty as adding 30 bits to a symmetric key.
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What is your definition of cracked? Collisions are easy to produce; there's one right on the Wikipedia page.
Collisions are not interesting. Millions of leaked passwords hashed with MD4/MD5 are of very practical interest.