Re: SRP + 3DES - secure enough?



"Rob Y." <ryampolsky@xxxxxxxxx> wrote in message news:7b323d77-a502-4d25-8495-cacf6c57f3dc@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
The process of producing the session keys via SRP will be enough to encrypt
the data in 3DES. It will not be feasible to recover the keys given only
cipher text from the handshakes.


Thanks. I figured that must be the case, but it's nice to hear it
stated so definitively.

So what about 3DES produces that security? Does it not use all of the
SRP-generated session key as a hash? Does it use some of the session
key to provide randomness in the 3DES algorithm itself?

You can read the wikipedia description of DES for more information on how the session key is used to produce the pseudo-random cipher-text from the plain-text. THe process of deriving the 3DES key from the SRP handshake should deliver 168 bits of random material, and that would be a result of your implementation. Is there any reason you are not using AES-128?

karl m

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Relevant Pages

  • Re: SRP + 3DES - secure enough?
    ...  It will not be feasible to recover the keys given only ... cipher text from the handshakes. ... SRP-generated session key as a hash? ...
    (sci.crypt)
  • Re: Hashing methods for giant keys
    ... Since there is a different session key for every message I ... Simply XORing each character of the password with a different ... The cipher text is twice the length ... second byte holds a composite key that is loaded into a simple array. ...
    (sci.crypt)
  • Re: Any pitfals of my stream cipher?
    ... If you had actually described a cipher system then a more ... How is the session key derived? ... What is the transmission code? ... only way is to brute force the master key ...
    (sci.crypt)
  • Re: Any pitfals of my stream cipher?
    ... their master password to derive the session key. ... How long are these portions of the session key? ... What is the transmission code? ... Also this isn't a stream cipher, it appears to be a method of using a stream cipher to build a block system, just use a block system it will save you a lot of headaches and errors. ...
    (sci.crypt)
  • TLS cipher control
    ... I used PowerTCP as my TLS package. ... All clients get handshakes. ... the cipher is selected by the CryptoAPI which the Tool uses. ...
    (microsoft.public.dotnet.security)