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invesdwin / invesdwin-context-security

invesdwin-context modules that provide security features
GNU Lesser General Public License v3.0
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integrate key exchange protocol for sharing keys/passwords without sending them over the wire #4

Closed subes closed 2 years ago

subes commented 2 years ago

From: https://github.com/invesdwin/invesdwin-context-integration/issues/19#issuecomment-1186588462

I guess the best approach would be to create a TLS connection using private/public keys, exchange a randomly generated key through that and then use HKDF to derive the other keys from that random key.

User credentials could be checked without transmitting the password via SRP6:

Though in our case we don't want to register users which requires storage of some information. That would be rather something that could be used for a frontend based authentication that should be keyless.

When password is public, SRP6 is only as secure as diffie hellman: https://crypto.stackexchange.com/questions/8314/does-srp-reduce-to-dh-key-exchange-when-shared-password-is-not-secret

subes commented 2 years ago

J-Pake would be an alternative where both parties know the same passwort but don't communicate that over the wire: org.bouncycastle.crypto.agreement.jpake.JPAKEParticipant

http://www.diva-portal.org/smash/get/diva2:1354154/FULLTEXT01.pdf (explanation of the shared password symmetric key exchange)

So this would be a Balanced PAKE type.

I guess the same could be achieved by using a fixed salt (the password) in SRP6a that is shared (which then makes it SRP6 which is a balanced PAKE instead of the augmented SRP6a)?

subes commented 2 years ago

ECDH uses ephemeral public/private keys that are immediately discarded afterwards: https://goteleport.com/blog/ssh-handshake-explained/

They use ECDH for key exhange. They seem to use AES-128 for performance reasons. HMAC-SHA256 for verification.

DiffieHelman explained: https://www.youtube.com/watch?v=NmM9HA2MQGI

Teleport algos: image

subes commented 2 years ago

done, we now have DH, ECDH, JPake, SRP6, TLS as handshakers in invesdwin-context-integration-channel (crypto package)