vernam-cipher one-time-pad

An absolutely secure method, which presently is the only provable one, is the Vernam-cipher (also called one-time-pad 1) [6, p. 47ff]. Thereby the key k has to be as long as the to-enciphered cleartext m, because each element of the key k is used only once [6, p. 51ff]. Whithout the knowledge of the cleartext m or the key k it is impossible, even with every effort, to conclude from the ciphertext c to the cleartext m [6, p. 51ff].

1: "In former times keyletters were written on pieces of a paper block. As soon as one keyletter had been used the piece of paper was ripped off and destroyed." [6, p. 52]

6: Albrecht Beutelspacher: Kryptologie: Eine Einführung in die Wissenschaft vom Verschlüsseln, Verbergen und Verheimlichen, Vieweg-Verlag, 2002

vernam-cipher one-time-pad
An absolutely secure method, which presently is the only provable one, is the Vernam-cipher (also called one-time-pad
1
Begin of reference "In former times keyletters were written on pieces of a paper block. As soon as one keyletter had been used the piece of paper was ripped off and destroyed."
[6, p. 52]
Begin of reference - Albrecht Beutelspacher: Kryptologie: Eine Einführung in die Wissenschaft vom Verschlüsseln, Verbergen und Verheimlichen, Vieweg-Verlag, 2002  - End of reference
End of reference
)
[6, p. 47ff]
Begin of reference - Albrecht Beutelspacher: Kryptologie: Eine Einführung in die Wissenschaft vom Verschlüsseln, Verbergen und Verheimlichen, Vieweg-Verlag, 2002  - End of reference
. Thereby the key k has to be as long as the to-enciphered cleartext m, because each element of the key k is used only once
[6, p. 51ff]
Begin of reference - Albrecht Beutelspacher: Kryptologie: Eine Einführung in die Wissenschaft vom Verschlüsseln, Verbergen und Verheimlichen, Vieweg-Verlag, 2002  - End of reference
. Whithout the knowledge of the cleartext m or the key k it is impossible, even with every effort, to conclude from the ciphertext c to the cleartext m
[6, p. 51ff]
Begin of reference - Albrecht Beutelspacher: Kryptologie: Eine Einführung in die Wissenschaft vom Verschlüsseln, Verbergen und Verheimlichen, Vieweg-Verlag, 2002 - End of reference
.