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46 lines
1.5 KiB
Plaintext
46 lines
1.5 KiB
Plaintext
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We need a new name for this intentionally-vague block of data.
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This block is a bencoded dictionary. All buckets hold an identical copy. The
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hash of the serialized data is kept in the URI.
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The download process must obtain a valid copy of this data before any
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decoding can take place. The download process must also obtain other data
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before incremental validation can be performed. Full-file validation (for
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clients who do not wish to do incremental validation) can be performed solely
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with the data from this block.
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At the moment, this data block contains the following keys:
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size
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segment_size
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num_segments
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needed_shares
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total_shares
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codec_name
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codec_params
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tail_codec_params
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share_root_hash
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fileid
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plaintext_root_hash
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verifierid
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crypttext_root_hash
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Some pieces are needed elsewhere (size should be visible without pulling the
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block, the Tahoe3 algorithm needs total_shares to find the right peers, all
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peer selection algorithms need needed_shares to ask a minimal set of peers).
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Some pieces are arguably redundant but are convenient to have present
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(test_encode.py makes use of num_segments).
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fileid/verifierid need to be renamed 'plaintext_hash' and 'crypttext_hash'
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respectively.
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The rule for this data block is that it should be a constant size for all
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files, regardless of file size. Therefore hash trees (which have a size that
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depends linearly upon the number of segments) are stored elsewhere in the
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bucket, with only the hash tree root stored in this data block.
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