TPM2.0 hashing with just the device node

tpm2_hash.py

import binascii
import struct
import logging

logger = logging.getLogger()
#logger.setLevel(logging.DEBUG)

TPM2_ST_NO_SESSIONS = 0x8001

TPM2_CC_Hash = 0x0000017D
TPM2_ALG_SHA1 = 0x0004
TPM_RH_NULL = 0x40000007


def main():

    str = "The quick brown fox jumps over the lazy dog"
    print "SHA-1 hash of the string: " + str

    try:
        f = open('/dev/tpm0', 'r+b')
    except IOError, e:
        logging.error('Error opening the device %s: \n%r' %
            ('/dev/tpm0', e))
        raise SystemExit(1)

## Hash
    fmt = '>HIIH43sHI'
    cmd = struct.pack(fmt,
                      TPM2_ST_NO_SESSIONS,
                      struct.calcsize(fmt),
                      TPM2_CC_Hash,
                      len(str),
                      str,
                      TPM2_ALG_SHA1,
                      TPM_RH_NULL)

    logging.debug('Cmd =' + binascii.hexlify(cmd[0:]))
    f.write(cmd)
    rsp = f.read()
    logging.debug('Res =' + binascii.hexlify(rsp[0:]))

    print('Hash=' + binascii.hexlify(rsp[-28:-8]))

if __name__ == "__main__":
    main()