13fc32feec
The irony of asserting copyright on this code is not lost on me. However, it's become a trigger response whenever I release anything to the world now :).
114 lines
4.0 KiB
Python
Executable File
114 lines
4.0 KiB
Python
Executable File
#!/usr/bin/env python
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# Copyright (c) 2010, Rich Wareham <richwareham@gmail.com>
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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# * Neither the name of the <organization> nor the
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# names of its contributors may be used to endorse or promote products
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# derived from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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import string, random
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MASTER_KEY_SRC = 'master-key.txt'
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def read_key_file(filelike):
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"""Read a HDCP master key from a key file.
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The key file is formatted into 40*40 56-bit hex values separated by
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white space. The first 40 values correspond to row 1 of the matrix, the
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next 40 row 2, etc. Lines beginning with a '#' are ignored. """
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key_matrix = [ [] ]
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for line in filelike:
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if line[0] == '#':
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# This is a comment... skip
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continue
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# split the line into words and parse the hex
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for entry in map(lambda x: int(x, 16), string.split(line)):
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# do we need to start a new row?
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if len(key_matrix[-1]) >= 40:
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key_matrix.append([])
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# append this entry to the row
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key_matrix[-1].append(entry)
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# check we read the right number of entries in total
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assert( len(key_matrix) == 40 )
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assert( len(key_matrix[-1]) == 40 )
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return key_matrix
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def gen_source_key(key_matrix):
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"""Generate a source key from the master key matrix passed.
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To generate a source key, take a forty-bit number that (in binary)
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consists of twenty ones and twenty zeroes; this is the source KSV. Add
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together those twenty rows of the matrix that correspond to the ones in
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the KSV (with the lowest bit in the KSV corresponding to the first
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row), taking all elements modulo two to the power of fifty-six; this is
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the source private key."""
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# generate KSV - 20 1s and 20 0s
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ksv = (['1'] * 20) + (['0'] * 20)
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# permute KSV
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random.shuffle(ksv)
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# convert the binary to int
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ksv_val = int(string.join(ksv, ''), 2)
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# zip the master key matrix and the ksv s.t. the LSB of KSV is associated with
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# the first row, etc. Then filter to only select those rows where the
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# appropriate bit of the KSV is 1.
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ksv.reverse()
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master_rows = map(lambda x: x[1], filter(lambda x: x[0] == '1', zip(ksv, key_matrix)))
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# now generate the key
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key = [0] * 40
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for row in master_rows:
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# add row to key
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key = map(lambda x: (x[0] + x[1]) & 0xffffffffffffff, zip(key, row))
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return (ksv_val, key)
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def output_human_readable(ksv, key):
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"""Print a human readable version of the KSV and key.
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The KSV is a single integer. The key is a list of 40 integers."""
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# output the ksv
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print 'KSV:'
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print '%010x' % ksv
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# output the key
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key_strs = map(lambda x: '%014x' % x, key)
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print '\nKey:'
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print string.join(map(lambda x: string.join(x, ' '), zip(*[key_strs]*5)), '\n')
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# read the master key file
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key_matrix = read_key_file(open(MASTER_KEY_SRC))
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# generate a source key and output it
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output_human_readable(*gen_source_key(key_matrix))
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