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5

The SNI extension is plain text in the ClientHello. This means that it is possible to passively snoop the value and redirect the traffic. This is already used in practice, i.e. haproxy has this feature for several years.


3

That doesn't hide Bob's identity from eavesdroppers. (The OP mentioned in chat that the OP isn't trying to do that.) I can no longer spot any other problems with the key exchange part. The encryption/decryption of application level data is vulnerable to arbitrary replays and reflection and dropping. ‚Äč The public MAC input should indicate direction and ...


1

You can use ephemeral Diffie-Hellman and then use RSA to authenticate the parameters and established key seed the same way as TLS does. Java Card implementations usually contain an implementation of ECDH key agreement. An advantage is that you don't need very large key sizes to be reasonably secure. Furhtermore, ECDH operation and key pair generation is ...


1

Both RSA and DH have a similarity which is the Modulus Exponential (modexp) function (RSA encrypt/decrypt function). Since both RSA and DH uses the same modexp function, you can make full use of the Cipher for ALG_RSA_NOPAD in JavaCard's crypto API. I have sat down and taken time to adapt the RSA crypto functions for traditional non-ECC type of DH functions ...


1

Diffie-Hellman relies on a mathematical problem on positive integers. To use it with bytes you just have to convert the bytes to - or use the bytes as - an integer. Usually this would be a unsigned big-endian (or network order) integer. For Diffie-Hellman the parameters consist of the modulus and the base. The public value could be 1024 bits (128 bytes). ...



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