Re: [Linux-ima-user] verifying measurements list with PCR10

[adrian g. <adr...@gm...>]

hi, i tried again to verify the measurements, this time in C:
i followed closely to the pseudo code provided in the ima INSTALL file:

    char fileName[50] = "ascii_runtime_measurements";
    unsigned char*    buf, event;

    memset(PCR, 0, SHA_DIGEST_LENGTH);
    while(fgets(event, 1024, fd_bin_measurements) != NULL) {

        buf = event + 3; // skip to the start of the hash

        for(j = 0; j < SHA_DIGEST_LENGTH; j++){
            strncpy(testText, buf + 2*j, 2);
            intResult = convertToInt(testText);  //change 2 bytes of char,
take it as a hex number and change it to int
                                                                // intResult
will be between 0 to 255.
            memset(tempPointer + j, intResult, 1);
        }

        SHA1_Init(&c);
        SHA1_Update(&c, PCR, SHA_DIGEST_LENGTH);
        SHA1_Update(&c, tempPointer, SHA_DIGEST_LENGTH);
        SHA1_Final(PCR, &c);
    }

i assume using the ascii file is alright and i checked the convertToInt
function and it converts correctly.
i also ran it several times since a new version of my program generates a
new reading.

thank you- adrian

On Wed, Oct 8, 2008 at 10:58 AM, adrian golding <adr...@gm...>wrote:

> i am trying to write a simple python script to verify my measurements list
> with PCR10 but it doesn't match.  Anybody see the mistake?
> thank you - adrian
>
> previousPCRValue = "0000000000000000000000000000000000000000"
>
> for line in obtainedFile.readlines():
>
>     lineArray = str.split(line)
>     # using ascii measurements file, lineArray[1] is the hash value
>
>     # concatenation
>     combineHex    = previousPCRValue + lineArray[1]
>     # change to binary
>     combineBinary     = binascii.unhexlify(combineHex)
>     # hash it
>     computedHash = hashlib.sha1(combineBinary)
>     # change it to hex
>     previousPCRValue = computedHash.hexdigest()
>
>
>