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REF ID:A58137
PRELIMINARY HISTORICAL REPORT
ON THE
SOLUTION OF THE "B" MACHINE*
| William F. Friedman, |
| Principal Cryptanalyst. |
| October 14, 1940. |
- *After 23 October 1940 this machine was, for security purposes designated as the "Purple System." WFF
Declassified and approved for release by NSA on 08-14-2013 pursuant to E.O. 13526
