ðeɪ ɐdˈɑːptᵻd ðə vˈɜːtʃuːəli ʌnbɹˈeɪkəbəl wˈʌntˈaɪmpˈæd sˈɪstəm, ðˈɛɹfoːɹ ᵻlˈɪmᵻnˌeɪɾɪŋ ðɪ ɐbˈɪləɾi ʌvðə bɹˈɪɾɪʃ dʒˌiːsˈiː ænd sˌiːˈɛs tə dᵻsˈaɪfɚɹ ˌɛni hˈaɪ ɡɹˈeɪd sˈoʊviət mˈɛsɪdʒᵻz fɹʌm nˈaɪntiːnhˈʌndɹɪd twˈɛnti sˈɛvən ʌntˈɪl ðɪ ˈɛnd ʌvðə sˈɛkənd wˈɜːld wˈɔːɹ.
They adopted the virtually unbreakable one-time-pad system, therefore eliminating the ability of the British GC&CS to decipher any high grade Soviet messages from 1927 until the end of the Second World War.