[Opensc-devel] Derive key with opensc

[klc k. <klc...@gm...>]

Hi,

I tried to derive key with opensc v14.0 pkcs11-tool on PIV card.

First I generated ec key with openssl using these commands:


   - openssl ecparam -in secp384r1param.pem -genkey -noout -out
   secp384r1key.pem
   - openssl ec -in secp384r1key.pem -out secp384r1key.der -pubout -outform
   der
   - pkcs11-tool.exe --module opensc-pkcs11.dll --derive -l -pin #### -id
   03 -i secp384r1key.der

This gave me error:

   - Cannot open n: m

Which basically says that it can't open the file. [origin:
pkcs11-tool->derive_key()->BIO_read_filename(bio_in, opt_input)]

I tried with pem format & it gave me error: Cannot read EC key from
secp384r1.pem

My question is

   - whether the format in which I am passing key to opensc is right?
   - Is there anything else I am missing to provide as an input to tool?
   - Is my operation correct?

Basically I am trying to write my own application with help of OpenSC
implementation to derive a key. Following is the overview of the process I
am trying to implement:

   - Application will receive x & y coordinate for EC public key.
   - Calculated EC key length with help of getEC_POINT() (modified received
   length as (length - 3) * 8 to adjust to EC key size (in this case 384 bits,
   I receive 51)).
   - Generated eckey according to key length with EC_KEY_new
   by_curve_name(NID_secp384r1) function.
   - Then called function EC_KEY_generate_key(eckey) function
   - ecgroup = EC_KEY_get0_group(eckey)
   - pub = EC_POINT_new(ecgroup)
   - Converted coordinates to big number with BN_bin2bn() function.
   - Computed octet string with EC_POINT_point2oct(ecgroup, pub,
   POINT_CONVERSION_UNCOMPRESSED, str_buf, str_buf_len, NULL). [Please note
   till this point execution goes successfully & I receive octet string].
   - Then according to opensc derive_key() function I coded new key
   template & ECDH parameters. I tried both mechanisms:
   CKM_ECDH1_COFACTOR_DERIVE, CKM_ECDH1_DERIVE
   - Till this point everything goes smoothly.
   - When call to C_DeriveKey() is made I get error as "*Security status
   not satisfied*" (Login is performed right before derive operation).
   - Transmitted APDU conforms to the NIST specification: 00 87 14 9D 67 7C
   65 82 00 85 61 04 X-coordinate Y-coordinate (48 bytes each).
   - Received APDU is 69 82.

Also the private key field_length parameter in opensc is set to half of the
EC key size. I get 192 bits for 384 bits EC key. Is this right? Is there
any other function to retrieve actual value of EC key; as now I am
modifying received value to drive successful execution (source:
pkcs15-sec.c)

I tried to find help on this but to no avail. Can you please guide me on
what might be the issue.

PS: I generated EC keys through Charismathics security token configurator &
performing derive operation with key Management key.

Thanks,
K