5 ms·

https://www.latacora.com/blog/2019/07/16/the-pgp-problem/#the-answers https://www.latacora.com/blog/2019/07/16/the-pgp-problem/#th...

by akerl_ 10mo ago

johnisgood 10mo ago
Saw it, not impressed, GnuPG has a lot of more features than signing and file encryption. And there are lots of tools for file encryption anyways. I have a bash function using openssh, sometimes I use croc (also uses PAKE), etc. I need an alternative to "gpg --encrypt --armor --recipient <foo>". :)
- akerl_ 10mo ago
  I guess we'll have to live with you being unimpressed.
- some_furry 10mo ago
  > I need an alternative to "gpg --encrypt --armor --recipient <foo>" That's literally age. https://github.com/FiloSottile/age https://github.com/FiloSottile/age
  - johnisgood 10mo ago
    No, because there is no keyring and you have to supply people's public key each time. It is not suitable for large-scale public key management (with unknown recipients), and it does not support automatic discovery, trust management. Age does NOT SUPPORT signing at all either.
    - some_furry 10mo ago
      Why is a keyring important to you? Would "fetch a short-lived age public key" serve your use case? If so, then an age plugin that build atop the AuxData feature in my Fediverse Public Key Directory spec might be a solution. https://github.com/fedi-e2ee/public-key-directory-specification/blob/main/Specification.md#auxiliary-data https://github.com/fedi-e2ee/public-key-directory-specificat... But either way, you shouldn't have long-lived public keys used for confidentiality. It's a bad design to do that.
      - johnisgood 10mo ago
        > you shouldn't have long-lived public keys used for confidentiality. This statement is generic and misleading. Using long-lived keys for confidentiality is bad in real-time messaging, but for non-ephemeral use cases (file encryption, backups, archives) it is completely fine AND desired. > Would "fetch a short-lived age public key" serve your use case? Sadly no.
        soatok 10mo ago
        (This is some_furry, I'm currently rate-limited. I thought this warranted a reply, so I switched to this account to break past the limit for a single comment.) > This statement is generic and misleading. It may be generic, but it's not misleading. > Using long-lived keys for confidentiality is bad in real-time messaging, but for non-ephemeral use cases (file encryption, backups, archives) it is completely fine. What exactly do you mean by "long-lived"? The "lifetime" of a key being years (for a long-lived backup) is less important than how many encryptions are performed with said key. The thing you don't want is to encrypt 2^50 messages under the same key. Even if it's cryptographically safe to do that, any post-compromise key rotation will be a fucking nightmare. The primary reason to use short-lived public keys is to limit the blast radius. Consider these two companies: Alice Corp. uses the same public key for 30+ years. Bob Ltd. uses a new public key for each quarter over the same time period. Both parties might retain the secret key indefinitely, so that if Bob Ltd. needs to retrieve a backup from 22 years ago, they still can. Now consider what happens if both of them lose their currently-in-use secret key due to a Heartbleed-style attack. Alice has 30 years of disaster recovery to contend with, while Bob only has up to 90 days. Additionally, file encryption, backups, and archives typically use ephemeral symmetric keys at the bottom of the protocol. Even when a password-based key derivation function is used (and passwords are, for whatever reason, reused), the password hashing function usually has a random salt, thereby guaranteeing uniqueness. The idea that "backups" magically mean "long-lived" keys are on the table, without nuance, is extremely misleading. > > Would "fetch a short-lived age public key" serve your use case? > Sadly no. shrug Then, ultimately, there is no way to securely satisfy your use case.
        10mo ago
    - amluto 10mo ago
      > you have to supply people's public key each time Keyrings are awful. I want to supply people’s public keys each time. I have never, in my entire time using cryptography, wanted my tool to guess or infer what key to verify with. (Heck, JOSE has a long history of bugs because it infers the key type, which is also a mistake.) I have an actual commercial use case that receives messages (which are, awkwardly, files sent over various FTP-like protocols, sigh), decrypts and verifies them, and further processes them. This is fully automated and runs as a service. For horrible legacy reasons, the files are in PGP format. I know the public key with which they are signed (provisioned out of band) and I have the private key for decryption (again, provisioned out of band). This would be approximately two lines of code using any sane crypto library [0], but there really isn’t an amazing GnuPG alternative that’s compatible enough. But GnuPG has keyrings, and it really wants to use them and to find them in some home directory. And it wants to identify keys by 32-bit truncated hashes. And it wants to use Web of Trust. And it wants to support a zillion awful formats from the nineties using wildly insecure C code. All of this is actively counterproductive. Even ignoring potential implementation bugs, I have far more code to deal with key rings than actual gpg invocation for useful crypto. [0] I should really not have to even think about the interaction between decryption and verification. Authenticated decryption should be one operation, or possibly two. But if it’s two, it’s one operation to decapsulate a session key and a second operation to perform authenticated decryption using that key.
      - upofadown 10mo ago
        >And it wants to identify keys by 32-bit truncated hashes. That's 64 bits these days. >I should really not have to even think about the interaction between decryption and verification. Messaging involves two verifications. One to insure that you are sending the message to who you think you are sending the message. The other to insure that you know who you received a message from. That is an inherent problem. Yes, you can use a shared key for this but then you end up doing both verifications manually.
        amluto 10mo ago
        >> And it wants to identify keys by 32-bit truncated hashes. > That's 64 bits these days. The fact that it’s short enough that I even need to think about whether it’s a problem is, frankly, pathetic. > Messaging involves two verifications. One to insure that you are sending the message to who you think you are sending the message. The other to insure that you know who you received a message from. That is an inherent problem. Yes, you can use a shared key for this but then you end up doing both verifications manually. I can’t quite tell what you mean. One can build protocols that do encrypt-then-sign, encrypt-and-sign, sign-then-encrypt, or something clever that combines encryption and signing. Encrypt-then-sign has a nice security proof, the other two combinations are often somewhat catastrophically wrong, and using a high quality combination can have good performance and nice security proofs. But all of the above should be the job of the designer of a protocol, not the user of the software. If my peer sends me a message, I should provision keys, and then I should pass those keys to my crypto library along with a message I received (and perhaps whatever session state is needed to detect replays), and my library should either (a) tell me that the message is invalid and not give me a guess as to its contents or (b) tell me it’s valid and give me the contents. I should not need to separately handle decryption and verification, and I should not even be able to do them separately even if I want to.
    - Natanael_L 10mo ago
      What you described IS WHY age is the better option. GPG's keyring handling has also been a source of exploits. It's much safer to directly specify recipient rather than rely on things like short key IDs which can be bruteforced. Automatic discovery simply isn't secure if you don't have an associated trust anchor. You need something similar to keybase or another form of PKI to do that. GPG's key servers are dangerous. You technically can sign with age, but otherwise there's minisign and the SSH spec signing function
    - pseudohadamard 10mo ago
      And when do you need any of that stuff? As a followup, is there anything in existence that supports "large-scale public key management (with unknown recipients)"? Or "automatic discovery, trust management"? Even X.509 PKI at its most delusional doesn't claim to be able to do that.
- baobun 10mo ago
  sq (sequoia) should be able to sort that.
  - johnisgood 10mo ago
    I know, I have been using it recently.
jhgb 10mo ago
> Use Signal. Or Wire, or WhatsApp, or some other Signal-protocol-based secure messenger. That's a "great" idea considering the recent legal developments in the EU, which OpenPGP, as bad as it is, doesn't suffer from. It would be great if the author updated his advice into something more future-proof.
- akerl_ 10mo ago
  There's no future-proof suggestion that's immune to the government declaring it a crime. If you want a suggestion for secure messaging, it's Signal/WhatsApp. If you want to LARP at security with a handful of other folks, GPG is a fine way to do that.
  - jhgb 10mo ago
    Nobody decided that it's a crime, and it's unlikely to happen. Question is, what do you do with mandatory snooping of centralized proprietary services that renders them functionally useless aside from "just live with it". I was hoping for actual advice rather than a snarky non-response, yet here we are.
    - akerl_ 10mo ago
      I gave you the answer that exists: I'm not aware of any existing or likely-to-exist secure messaging solution that would be a viable recommendation. The available open-source options come nowhere close to the messaging security that Signal/Whatsapp provide. So you're left with either "find a way to access Signal after they pull out of whatever region has criminalized them operating with a backdoor on comms" or "pick any option that doesn't actually have strong messaging security".
      - johnisgood 10mo ago
        > messaging security > WhatsApp Eh? There are alternatives, try Ricochet (Refresh) or Cwtch.

https://www.latacora.com/blog/2019/07/16/the-pgp-problem/#the-answers https://www.latacora.com/blog/2019/07/16/the-pgp-problem/#th...

by akerl_ 10mo ago

https://www.latacora.com/blog/2019/07/16/the-pgp-problem/#the-answers https://www.latacora.com/blog/2019/07/16/the-pgp-problem/#th...

johnisgood 10mo ago

Saw it, not impressed, GnuPG has a lot of more features than signing and file encryption. And there are lots of tools for file encryption anyways. I have a bash function using openssh, sometimes I use croc (also uses PAKE), etc. I need an alternative to "gpg --encrypt --armor --recipient <foo>". :)

akerl_ 10mo ago
I guess we'll have to live with you being unimpressed.
some_furry 10mo ago
> I need an alternative to "gpg --encrypt --armor --recipient <foo>" That's literally age. https://github.com/FiloSottile/age https://github.com/FiloSottile/age
- johnisgood 10mo ago
  No, because there is no keyring and you have to supply people's public key each time. It is not suitable for large-scale public key management (with unknown recipients), and it does not support automatic discovery, trust management. Age does NOT SUPPORT signing at all either.
  - some_furry 10mo ago
    Why is a keyring important to you? Would "fetch a short-lived age public key" serve your use case? If so, then an age plugin that build atop the AuxData feature in my Fediverse Public Key Directory spec might be a solution. https://github.com/fedi-e2ee/public-key-directory-specification/blob/main/Specification.md#auxiliary-data https://github.com/fedi-e2ee/public-key-directory-specificat... But either way, you shouldn't have long-lived public keys used for confidentiality. It's a bad design to do that.
    - johnisgood 10mo ago
      > you shouldn't have long-lived public keys used for confidentiality. This statement is generic and misleading. Using long-lived keys for confidentiality is bad in real-time messaging, but for non-ephemeral use cases (file encryption, backups, archives) it is completely fine AND desired. > Would "fetch a short-lived age public key" serve your use case? Sadly no.
      - soatok 10mo ago
        (This is some_furry, I'm currently rate-limited. I thought this warranted a reply, so I switched to this account to break past the limit for a single comment.) > This statement is generic and misleading. It may be generic, but it's not misleading. > Using long-lived keys for confidentiality is bad in real-time messaging, but for non-ephemeral use cases (file encryption, backups, archives) it is completely fine. What exactly do you mean by "long-lived"? The "lifetime" of a key being years (for a long-lived backup) is less important than how many encryptions are performed with said key. The thing you don't want is to encrypt 2^50 messages under the same key. Even if it's cryptographically safe to do that, any post-compromise key rotation will be a fucking nightmare. The primary reason to use short-lived public keys is to limit the blast radius. Consider these two companies: Alice Corp. uses the same public key for 30+ years. Bob Ltd. uses a new public key for each quarter over the same time period. Both parties might retain the secret key indefinitely, so that if Bob Ltd. needs to retrieve a backup from 22 years ago, they still can. Now consider what happens if both of them lose their currently-in-use secret key due to a Heartbleed-style attack. Alice has 30 years of disaster recovery to contend with, while Bob only has up to 90 days. Additionally, file encryption, backups, and archives typically use ephemeral symmetric keys at the bottom of the protocol. Even when a password-based key derivation function is used (and passwords are, for whatever reason, reused), the password hashing function usually has a random salt, thereby guaranteeing uniqueness. The idea that "backups" magically mean "long-lived" keys are on the table, without nuance, is extremely misleading. > > Would "fetch a short-lived age public key" serve your use case? > Sadly no. shrug Then, ultimately, there is no way to securely satisfy your use case.
        10mo ago
  - amluto 10mo ago
    > you have to supply people's public key each time Keyrings are awful. I want to supply people’s public keys each time. I have never, in my entire time using cryptography, wanted my tool to guess or infer what key to verify with. (Heck, JOSE has a long history of bugs because it infers the key type, which is also a mistake.) I have an actual commercial use case that receives messages (which are, awkwardly, files sent over various FTP-like protocols, sigh), decrypts and verifies them, and further processes them. This is fully automated and runs as a service. For horrible legacy reasons, the files are in PGP format. I know the public key with which they are signed (provisioned out of band) and I have the private key for decryption (again, provisioned out of band). This would be approximately two lines of code using any sane crypto library [0], but there really isn’t an amazing GnuPG alternative that’s compatible enough. But GnuPG has keyrings, and it really wants to use them and to find them in some home directory. And it wants to identify keys by 32-bit truncated hashes. And it wants to use Web of Trust. And it wants to support a zillion awful formats from the nineties using wildly insecure C code. All of this is actively counterproductive. Even ignoring potential implementation bugs, I have far more code to deal with key rings than actual gpg invocation for useful crypto. [0] I should really not have to even think about the interaction between decryption and verification. Authenticated decryption should be one operation, or possibly two. But if it’s two, it’s one operation to decapsulate a session key and a second operation to perform authenticated decryption using that key.
    - upofadown 10mo ago
      >And it wants to identify keys by 32-bit truncated hashes. That's 64 bits these days. >I should really not have to even think about the interaction between decryption and verification. Messaging involves two verifications. One to insure that you are sending the message to who you think you are sending the message. The other to insure that you know who you received a message from. That is an inherent problem. Yes, you can use a shared key for this but then you end up doing both verifications manually.
      - amluto 10mo ago
        >> And it wants to identify keys by 32-bit truncated hashes. > That's 64 bits these days. The fact that it’s short enough that I even need to think about whether it’s a problem is, frankly, pathetic. > Messaging involves two verifications. One to insure that you are sending the message to who you think you are sending the message. The other to insure that you know who you received a message from. That is an inherent problem. Yes, you can use a shared key for this but then you end up doing both verifications manually. I can’t quite tell what you mean. One can build protocols that do encrypt-then-sign, encrypt-and-sign, sign-then-encrypt, or something clever that combines encryption and signing. Encrypt-then-sign has a nice security proof, the other two combinations are often somewhat catastrophically wrong, and using a high quality combination can have good performance and nice security proofs. But all of the above should be the job of the designer of a protocol, not the user of the software. If my peer sends me a message, I should provision keys, and then I should pass those keys to my crypto library along with a message I received (and perhaps whatever session state is needed to detect replays), and my library should either (a) tell me that the message is invalid and not give me a guess as to its contents or (b) tell me it’s valid and give me the contents. I should not need to separately handle decryption and verification, and I should not even be able to do them separately even if I want to.
  - Natanael_L 10mo ago
    What you described IS WHY age is the better option. GPG's keyring handling has also been a source of exploits. It's much safer to directly specify recipient rather than rely on things like short key IDs which can be bruteforced. Automatic discovery simply isn't secure if you don't have an associated trust anchor. You need something similar to keybase or another form of PKI to do that. GPG's key servers are dangerous. You technically can sign with age, but otherwise there's minisign and the SSH spec signing function
  - pseudohadamard 10mo ago
    And when do you need any of that stuff? As a followup, is there anything in existence that supports "large-scale public key management (with unknown recipients)"? Or "automatic discovery, trust management"? Even X.509 PKI at its most delusional doesn't claim to be able to do that.
baobun 10mo ago
sq (sequoia) should be able to sort that.
- johnisgood 10mo ago
  I know, I have been using it recently.

jhgb 10mo ago

> Use Signal. Or Wire, or WhatsApp, or some other Signal-protocol-based secure messenger. That's a "great" idea considering the recent legal developments in the EU, which OpenPGP, as bad as it is, doesn't suffer from. It would be great if the author updated his advice into something more future-proof.

akerl_ 10mo ago
There's no future-proof suggestion that's immune to the government declaring it a crime. If you want a suggestion for secure messaging, it's Signal/WhatsApp. If you want to LARP at security with a handful of other folks, GPG is a fine way to do that.
- jhgb 10mo ago
  Nobody decided that it's a crime, and it's unlikely to happen. Question is, what do you do with mandatory snooping of centralized proprietary services that renders them functionally useless aside from "just live with it". I was hoping for actual advice rather than a snarky non-response, yet here we are.
  - akerl_ 10mo ago
    I gave you the answer that exists: I'm not aware of any existing or likely-to-exist secure messaging solution that would be a viable recommendation. The available open-source options come nowhere close to the messaging security that Signal/Whatsapp provide. So you're left with either "find a way to access Signal after they pull out of whatever region has criminalized them operating with a backdoor on comms" or "pick any option that doesn't actually have strong messaging security".
    - johnisgood 10mo ago
      > messaging security > WhatsApp Eh? There are alternatives, try Ricochet (Refresh) or Cwtch.