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colmmacc's profile
Colm MacCárthaigh
Colm MacCárthaigh
Colm MacCárthaigh
@colmmacc

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Colm MacCárthaigh

@colmmacc

AWS, Apache, Crypto, Irish Music, Haiku, Photography

Seattle
notesfromthesound.com
Joined April 2008

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    1. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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      Colm MacCárthaigh Retweeted Colm MacCárthaigh

      At re:Inforce we revealed two previously unannounced AWS network encryption features. One is embedded in our Nitro hardware security system, the other is for network links. But I want to take a second to zoom in just on multi-party key distribution ...https://twitter.com/colmmacc/status/1143572552180277248 …

      Colm MacCárthaigh added,

      Colm MacCárthaigh @colmmacc
      To avoid having any sensitive system that knows all of the keys; there are two independent, very different, key distribution mechanisms. Each distributes "pre-key material" which is then only combined in our Nitro security system to derive the real key.
      Show this thread
      1 reply 26 retweets 72 likes
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    2. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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      The root of trust in any cryptographic or authentication system is usually based on one or two things: key distribution, and high-quality randomness. With Nitro we also have our own high-quality hardware secure random number generators. Key distribution is a harder problem.

      3 replies 0 retweets 2 likes
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    3. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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      If your system depends on asymmetric keys; RSA, ECDSA, Ed25519, etc. then best practice is to generate public-private keys on a secure system and then only export the private key. This is a good practice but it comes with some challenges.

      2 replies 0 retweets 0 likes
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    4. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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      Firstly, you likely have to have a whole PKI infrastructure to make that practical. We do make it easier than ever to have a private certificate authority:https://aws.amazon.com/certificate-manager/private-certificate-authority/ …

      1 reply 0 retweets 3 likes
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    5. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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      Secondly, RSA, ECDSA, Ed25519, etc, aren't great with respect to Post-Quantum Security, which people are worrying about. There are fixes; they can supplemented with hybrid algorithms, and static pre-shared keys, but those need a way to share those keys.

      1 reply 0 retweets 2 likes
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      Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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      Thirdly, and most mundanely, sometimes you just need the same key on multiple hosts. That means we need a key distribution system! But key distribution systems make for very rich targets. That's not something to do lightly.

      7:42 AM - 26 Jun 2019
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      • Deirdre Connolly¹
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        2. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          The best answer here is to use a secure Key Management Service. We have https://aws.amazon.com/kms/ . KMS uses envelope encryption and support for bootstrapped mechanisms such as instance role accounts to get around all of this.

          1 reply 1 retweet 3 likes
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        3. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          With envelope encryption, there's a hierarchy of keys that encrypt other keys, ultimately protected by a hardware root of trust, which mean that KMS can distribute keys without ever having plaintext access to the keys themselves. Very cool. O.k. but ...

          2 replies 0 retweets 1 like
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        4. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          VPC Encryption and our Lever Link Encryption project sit at the very bottom of the AWS networking stacks. And KMS runs on top of this! We'd have a circular dependency if we "just" used KMS, so how do we achieve the same security properties?

          1 reply 1 retweet 4 likes
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        5. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          We distribute multiple "pre-secrets". One is distributed in a dedicated key distribution system. The other is distributed using existing configuration distribution systems. These "pre-secrets" are then mixed, using the HKDF key derivation function to make the actual key.

          1 reply 0 retweets 2 likes
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        6. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          This is incredibly simple; but it has the effect that if the pre-secrets in the key distribution systems become known somehow, that's not fatal to the system security, it doesn't disclose the actual keys we use.

          1 reply 0 retweets 2 likes
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        7. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          This technique works trivially for symmetric keys, but can also be used with a deterministic key generation algorithm to generate the same asymmetric keys on multiple hosts, without central knowledge.

          1 reply 0 retweets 2 likes
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        8. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          Boring, simple, patterns are re-assuring in cryptography and I really love this one, because for very little cost, it gives a very meaningful security property. It really surprises me that it isn't more common pattern.

          1 reply 0 retweets 2 likes
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        9. Colm MacCárthaigh‏ @colmmacc 26 Jun 2019
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          O.k. when I wrote "only export the private key" I *cough* meant "only export the PUBLIC key"! /end-of-thread

          5 replies 0 retweets 20 likes
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        10. End of conversation

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