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>> Every application on the phone is sandboxed Note that you are trusting this app with your private key. While other apps are sandboxed away from having acces

>> Every application on the phone is sandboxed Note that you are trusting this app with your private key. While other apps are sandboxed away from having access, all it takes is one update to the app to sneak away your private key to any remote server. You have to trust the publisher of this app, including their entire chain of source code repository management and app build/release process. It takes a single instance of a malicious person inserting code that steals all users' private keys (disgruntled employee at this company, or social engineering attack to gain access to commit to their GitHub, etc.). It's the same reason I am horrified that anyone trusts password managers from for-profit companies. Those companies have unfiltered potential access to your entire online identity, including critical logins like your bank and government services. The app is sandboxed, and the company promises that your (unencrypted) credentials never leave the local device. But it is impossible for them to offer an absolute guarantee that their app will never be the target of an attacker slipping in code that steals information. In this particular case, you're giving a single app access to potentially expose your key to theft. Less risky than storing your key in the default ~/.ssh/id_rsa, where any app running on your desktop machine has access to read it. Also likely to be less devastating of a loss compared to the compromise of the contents of a password manager.

mauz0r 9y ago
> Note that you are trusting this app with your private key. While other apps are sandboxed away from having access, all it takes is one update to the app to sneak away your private key to any remote server. You have to trust the publisher of this app, including their entire chain of source code repository management and app build/release process. It takes a single instance of a malicious person inserting code that steals all users' private keys (disgruntled employee at this company, or social engineering attack to gain access to commit to their GitHub, etc.). Fair point, not really applicable in this case though. It looks like everything you'll need you can find on their GitHub https://github.com/kryptco https://github.com/kryptco yourself. Which means, you could check/skim the code strange "phoning-home calls" and get rid of them in your own fork. It would be nice to have some security experts doing some code review :) > Also likely to be less devastating of a loss compared to the compromise of the contents of a password manager. I often compare this situation like when you've lost your actual keys/keychain. The person who find your key's needs to figure out where to use them (if you don't store the address with your key's you're kind of fine).. If someone find my private keys, github is something I would worry about the most. The good thing is you can add a passphrase to you ssh keys (something you can't do with your "real" / physical keys ;) )
- developer2 9y ago
  >> everything you'll need you can find on their GitHub The fact remains that app installs are bundles whose base source could come from anywhere. There's no guarantee that what you install from an app store was built from their GitHub. On a non-jailbroken iOS device, you're installing a closed-source binary with no inspection possible. I believe you could build your own Android apk from their GitHib, but how many users would ever do that (let alone rebuild it on every update)? As I mentioned, I suspect that the first attack against one of the major password managers will result from a commit to the official repository (ex: GitHub). Users are not looking at every commit to GitHub before updating an iOS app to make sure that the latest version doesn't have a backdoor. At the end of the day, you must trust the app publisher with your unencrypted data within the app. Anyway, for this ssh product, I wouldn't be all that worried. Password managers though... I'm waiting for the first attack to happen, at which point I can point to my HN history to show I saw it coming. ;)
divegeek 9y ago
>> Note that you are trusting this app with your private key. On Android, the Kryptonite code uses the AndroidKeyStore to store the private key, which means that the app does not have access to it. At a minimum (on old devices), AndroidKeyStore keeps the private key material in a separate process, so it never exists in the app's process space. On newer devices (launched with M or later), the private key material is kept in the Trusted Execution Environment, so nothing in Android user or even kernel space has access to it. EDIT: Actually, there's one small flaw in the Kryptonite code that may make the private key accessible to a sophisticated attacker who compromises the app. The key allows signing without using a hash function. Signing a sequence of carefully-chosen plaintexts can reveal the private key. I filed an issue and sent a pull request.

mauz0r 9y ago

> Note that you are trusting this app with your private key. While other apps are sandboxed away from having access, all it takes is one update to the app to sneak away your private key to any remote server. You have to trust the publisher of this app, including their entire chain of source code repository management and app build/release process. It takes a single instance of a malicious person inserting code that steals all users' private keys (disgruntled employee at this company, or social engineering attack to gain access to commit to their GitHub, etc.). Fair point, not really applicable in this case though. It looks like everything you'll need you can find on their GitHub https://github.com/kryptco https://github.com/kryptco yourself. Which means, you could check/skim the code strange "phoning-home calls" and get rid of them in your own fork. It would be nice to have some security experts doing some code review :) > Also likely to be less devastating of a loss compared to the compromise of the contents of a password manager. I often compare this situation like when you've lost your actual keys/keychain. The person who find your key's needs to figure out where to use them (if you don't store the address with your key's you're kind of fine).. If someone find my private keys, github is something I would worry about the most. The good thing is you can add a passphrase to you ssh keys (something you can't do with your "real" / physical keys ;) )

developer2 9y ago
>> everything you'll need you can find on their GitHub The fact remains that app installs are bundles whose base source could come from anywhere. There's no guarantee that what you install from an app store was built from their GitHub. On a non-jailbroken iOS device, you're installing a closed-source binary with no inspection possible. I believe you could build your own Android apk from their GitHib, but how many users would ever do that (let alone rebuild it on every update)? As I mentioned, I suspect that the first attack against one of the major password managers will result from a commit to the official repository (ex: GitHub). Users are not looking at every commit to GitHub before updating an iOS app to make sure that the latest version doesn't have a backdoor. At the end of the day, you must trust the app publisher with your unencrypted data within the app. Anyway, for this ssh product, I wouldn't be all that worried. Password managers though... I'm waiting for the first attack to happen, at which point I can point to my HN history to show I saw it coming. ;)

divegeek 9y ago

>> Note that you are trusting this app with your private key. On Android, the Kryptonite code uses the AndroidKeyStore to store the private key, which means that the app does not have access to it. At a minimum (on old devices), AndroidKeyStore keeps the private key material in a separate process, so it never exists in the app's process space. On newer devices (launched with M or later), the private key material is kept in the Trusted Execution Environment, so nothing in Android user or even kernel space has access to it. EDIT: Actually, there's one small flaw in the Kryptonite code that may make the private key accessible to a sophisticated attacker who compromises the app. The key allows signing without using a hash function. Signing a sequence of carefully-chosen plaintexts can reveal the private key. I filed an issue and sent a pull request.