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On 2020-08-28 17:53, Grant Taylor wrote: |
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> On 8/28/20 3:33 PM, Michael Orlitzky wrote: |
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>> TLS only secures the channel; what comes out at the end is a plain-text |
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>> message that can be read with minimal effort by the VPS provider, |
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>> no skullduggery needed. |
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> |
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> I agree that STARTTLS only protects the email while it's in flight |
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> between servers. |
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> |
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> Though I do think that it's going to somewhat difficult for a VPS |
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> provider to read the contents of the message if it's stored on an |
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> encrypted disk. |
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|
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The contents of the disk are unencrypted while the server is powered on, |
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or at least while the server is receiving email (while it's reading from |
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and writing to that disk). In practice that will be all the time -- you |
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can't log in and type the disk-encryption password every time an email |
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arrives. |
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>> Unless the sender and recipient have some pre-shared secret (like GPG |
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>> assumes), |
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> |
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> I *REALLY* thought that PGP (GPG) was based on public & private key |
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> pairs, much like S/MIME and TLS. |
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> |
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> As such, Alice and Bob can encrypt messages to each other, even through |
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> an untrusted medium such as a questionable email server. |
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> |
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> Yes, that still leaves the bootstraping issue of how do Alice and Bob |
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> get each other's public key. -- I defer to my recent comments about |
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> publishing keys in DNS and relying on DNSSEC. |
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> |
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GPG is based on public keys, but you've anticipated my response: |
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public-key encryption still requires you to verify that "my" public key |
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does in fact belong to *me* somehow. If you believe in the web of trust, |
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then someone you know (or someone someone you know knows...) has to have |
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met me in person and signed my key before it means anything to you. |
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I shouldn't have used the word "secret." Pre-established or out-of-band |
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authentication would have been more accurate. |
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With GPG, the trust is between you and I, and the VPS provider acts as |
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the eavesdropper. All three parties are distinct, and the security can |
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work. With TLS between MTAs, the trust is established on-the-fly between |
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the other MTA and the VPS provider, but the VPS provider still also |
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plays the the role of the eavesdropper. When the eavesdropper is |
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trusted, you're in trouble. |
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