[Bitcoin-development] Double-Spending Fast Payments in Bitcoin due to Client versions 0.8.1

[Arthur Gervais]

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Dear Bitcoin developers,

We would like to report a vulnerability which might lead, under some
assumptions, to a double-spending attack in a fast payment scenario.
The vulnerability has been introduced due to signature encoding
incompatibilities between versions 0.8.2 (or 0.8.3) and earlier
Bitcoin versions.

Please find at the following link a detailed description of this
vulnerability:
ftp://ftp.inf.ethz.ch/pub/publications/tech-reports/7xx/789.pdf

We contacted and informed Gavin earlier about this problem.

With best regards,
Arthur Gervais
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