Technical Details of Bitshares ID System

[AnonyMint]

Regarding the secure messaging feature, be aware of:

Signcryption

Digital Signcryption or How to Achieve
Cost(Signature & Encryption) <<
Cost(Signature) + Cost(Encryption)

Claims to eliminate the need to sign and encrypt in separate steps as PGP does. I didn't read it yet, just passing it along.

Signcryption, a kind of public key cryptosystem,
succeeds in simultaneously encrypting the message
while digitally signing. Compared with the traditional
systems like PGP that executes signing and encrypting
a message in sequential procedures, such a
characteristic makes signcryption system securer and
more efficient. To be specific, the efficiency of
performance based on the signcryption system can be
enhanced atout 50% to 90% than the traditional ones

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[AnonyMint]

Secure messaging system works as follows, if it can be modified to utilize the above that would be great.

Lookup User's pubic key with BitID  =>  RecvPublicKey

Generate a one-time PrivateKey  => SenderOneTimePrivKey and  SenderOneTimePublicKey

Calculate a ECDH shared secret...    SenderOneTimePrivKey * RecvKey  => Shared Secret.

Create your message  TXT
SIG = SendPrivKey.sign( SHA256(TXT) )

AES_ENCRYPT( SharedSecret,   (TXT + SIG) )  => EncryptedMessage

CHECK = SHA512( Shared Secret ).substr(4)

Broadcast:  SenderOneTimePublicKey + CHECK + EncryptedMessage

The receiver will then test each of their private keys like so:

RecvPrivateKey * SenderOneTimePublicKey => Recv Shared Secret
TEST(SHA512(Recv SharedSecret).substr(4) == CHECK)
AES_DECRYPT( Recv Shared Secret, EncryptedMessage )  =>  TXT + SIG

Recover SenderPublicKey via  SHA256(TXT) and SIG

Note:  this algorithm has not yet been audited so any feedback is appreciated.

I think signcrypt is useful for signing and encrypting short messages most efficiently, i.e. setup stage. Especially a designated verifier.

Check out Salsa20 encryption, I think it has superior qualities (e.g. faster, can send blocks out-of-order) over AES for encrypting the message content.

I am not a cryptography expert. Just based on what I have read.