DRAFT TOP SECRET CYPHER TELEGRAM FROM: CABINET OFFICE TO: J.S.M. WASHINGTON COS (W) February, 1946. Reference J.S.M. 184. Please inform War Department that it is impossible to assess whether and to what extent damage has been done by release of telegram in Appendix IV of A.D.B. in unparaphrased form. 2. Cypher Policy Board state that publication of this telegram may mean that all messages encyphered in "Typex" on that day could be read by a first-class cryptographic power and so damage British cypher security.