CODEWITHSUNDEEP
javacardglobalplatform
chris mode51
chris mode51

Reputation: 29

ConfigureISDPRequest error during profile package installation into an ISD-P on an eUICC

I'm assembling the SGP.22 GetBoundProfilePackage response that starts with the InitialiseSecureChannelRequest for which I'm getting a 90 00 success code. The subsequent ConfigureISDPRequest is returning an errorReason 8 which is an scp03t/BSP security error.

There are several steps for the scp03t (now relabelled as BSP in v3 of SGP.22) process and ConfigureISDPRequest requires encryption and MACing. The error code doesn't provide a way of identifying which step contains the error.

The first step is to generate the ShS shared secret using previously generated (for InitialiseSecureChannelRequest) smdpOtsk private key and euiccOtpk public key. This ECDH procedure is defined in NIST SP 800-56Ar3 section 5.7.1.2:

  1. Compute the point P = hdAQB.
  2. If P = Ø, destroy all intermediate values used in the attempted computation of P, then output an error indicator, and exit this process without further processing.
  3. Else, set z = xP, where xP is the x-coordinate of P, and convert z to Z, using the field- element-to-byte string conversion routine defined in Appendix C.2.

My Golang code, having referred to this post though I note I don't think it needs hashing after - that appears to be a TLS thing:

calcedX, _ := euiccOtpk.Curve.ScalarMult(euiccOtpk.X, euiccOtpk.Y, smdpOtsk.D.Bytes())

What isn't clear to me here is part 3 in the NIST SP 800-56Ar3 steps - convert z to Z, using the field-element-to-byte string conversion routine defined in Appendix C.2.

I've used the following code for the Field-Element-to-Byte String Conversion specified in Appendix C.2 and my question is whether or not this is correct?

    fixedBytes := make([]byte, 32)
    calcedX.FillBytes(fixedBytes)
    return fixedBytes

Upvotes: 1

Views: 81

Answers (1)

k_o_
k_o_

Reputation: 6298

  1. It seems you are implementing ECDH on your own? Does the default Golang impl does not work for you? If you implement the low level stuff by yourself this project will be endless. Test cectors for ECDH might be taken from wycheproof.
  2. Take a look into the test specification for SGP.22, search for ConfigureISDPRequest and related commands. Starting with Annex A you will find constants and data used in the test commands. It does not define real test vectors, but still helps to test your code interactions.

Upvotes: 0

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