Phelix writes:

Here ya go. 313 webtv sigs

Thanks. Each of these decodes to a pair of integer values, as described by Peter Gutmann. Here is a histogram of the high order hex digit: # Values Digit 54 0 35 1 56 2 49 3 43 4 50 5 47 6 57 7 45 8 43 9 49 a 54 b 44 c 0 d 0 e 0 f It cuts off at "c" and is pretty uniform up to then so it does indicate that the values are uniformly distributed modulo a common 64 bit value. The last few values, numerically, are: cac1cb18c3d20ca400db3a1458128bea3f696edf cae7ea1cff68371b6541a829d6a5327bf77b8ba4 cb6449fb156e3b7a0f9577a9163dab099540360d cb9e0b23cdfebac34c38a933fcf303a5ecac64eb cba8abfa8cdcfa7a7f91e3563b3d7fa24511ab6c cc1a7a3ac5107a17fd7d0957223a189ac9b692b7 cc4d60e041b32e85d8148a2a340f3ae6c2a6f02c cc9d2ed06373569225844c8b0bd2e7c55537ab71 cd53fb5bc7699730b39d42b99782fecfdfe52a5a This suggests that the "q" value is probably a 160 bit value starting with 0xcd. We can't tell whether there is a common key or whether every unit has a different key. In either case it is likely that p, q and g will be shared among all units. The individual part is the secret x value and the public y = g^x mod p. Probably there is no way to find these from the signatures. For reference, here is the 20 minute program which produced this output: /* Decode webtv signatures */ #include <stdio.h> #include <ctype.h> #define TAG_INTEGER 2 #define TAG_SEQUENCE 16 static unsigned char asctobin[] = { 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0076, 0200, 0200, 0200, 0077, 0064, 0065, 0066, 0067, 0070, 0071, 0072, 0073, 0074, 0075, 0200, 0200, 0200, 0200, 0200, 0200, 0200, 0000, 0001, 0002, 0003, 0004, 0005, 0006, 0007, 0010, 0011, 0012, 0013, 0014, 0015, 0016, 0017, 0020, 0021, 0022, 0023, 0024, 0025, 0026, 0027, 0030, 0031, 0200, 0200, 0200, 0200, 0200, 0200, 0032, 0033, 0034, 0035, 0036, 0037, 0040, 0041, 0042, 0043, 0044, 0045, 0046, 0047, 0050, 0051, 0052, 0053, 0054, 0055, 0056, 0057, 0060, 0061, 0062, 0063, 0200, 0200, 0200, 0200, 0200 }; /* Do base64 decoding */ /* Return number of chars output */ static int decode64 (const unsigned char *inbuf, unsigned char *outbuf) { int w = 0; int cnt = 0; int ci, co; unsigned char *op = outbuf; for ( ; ; ) { ci = (*inbuf++); if (ci & 0x80) break; co = asctobin[ci]; if (co & 0x80) break; w = (w << 6) | co; if (++cnt == 4) { *op++ = (w >> 16) & 0xff; *op++ = (w >> 8) & 0xff; *op++ = (w >> 0) & 0xff; cnt = 0; w = 0; } } if (cnt == 1) { fprintf (stderr, "Bad base64 input\n"); exit (1); } else if (cnt == 2) { *op++ = (w >> 4) & 0xff; } else if (cnt == 3) { *op++ = (w >> 10) & 0xff; *op++ = (w >> 2) & 0xff; } return op - outbuf; } /* Print out a nominally 20 byte value */ static void hexdump20 (unsigned char *data, size_t datalen) { if (datalen > 20) { int cnt = datalen - 20; while (cnt--) { if (*data++ != 0) { fprintf (stderr, "Error, more than 20 byte output\n"); return; } } datalen = 20; } if (datalen < 20) { int cnt = 20 - datalen; while (cnt--) printf ("00"); } while (datalen--) { printf ("%02x", *data++); } putchar ('\n'); } /* Read start of an X.509 object */ static int decodetag(unsigned char **buf, int *length) { unsigned char tag = *(*buf)++ & 0x1f; int len = *(*buf)++; if (len & 0x80) { int lenlen = len & 0x7f; len = 0; while (lenlen--) { len <<= 8; len |= *(*buf)++; } } *length = len; return tag; } main () { unsigned char buf[1024]; unsigned char *bp; unsigned char outbuf[1024]; unsigned char *op; int outlen; int len; int tag; while (fgets(buf, sizeof(buf), stdin)) { bp = buf; while (isspace(*bp)) ++bp; outlen = decode64 (bp, outbuf); if (outbuf[0] != 0x11) { fprintf (stderr, "First char of output not 0x11, unexpected!\n"); } op = outbuf + 1; tag = decodetag (&op, &len); if (tag != TAG_SEQUENCE) { fprintf (stderr, "Output is not a SEQUENCE, skipping\n"); continue; } tag = decodetag (&op, &len); if (tag != TAG_INTEGER) { fprintf (stderr, "First value is not an INTEGER, skipping\n"); continue; } hexdump20 (op, len); op += len; tag = decodetag (&op, &len); if (tag != TAG_INTEGER) { fprintf (stderr, "Second value is not an INTEGER, skipping\n"); continue; } hexdump20 (op, len); } exit (0); }