From 4243690e66da50586ea85b10aeb886d2b1463703 Mon Sep 17 00:00:00 2001
From: Peter Gerwinski <peter.gerwinski@hs-bochum.de>
Date: Wed, 17 Jan 2024 15:16:52 +0100
Subject: [PATCH] Screenshots und Beispiele 11.1.2024
---
20240111/diffie-hellman.txt | 14 ++++++++++++
20240111/hashes-01.txt | 10 +++++++++
20240111/mac-01.txt | 9 ++++++++
20240111/man-in-the-middle.txt | 41 ++++++++++++++++++++++++++++++++++
20240111/random-01.c | 10 +++++++++
20240111/random-02.c | 10 +++++++++
20240111/random-03.c | 11 +++++++++
20240111/random-04.c | 12 ++++++++++
8 files changed, 117 insertions(+)
create mode 100644 20240111/diffie-hellman.txt
create mode 100644 20240111/hashes-01.txt
create mode 100644 20240111/mac-01.txt
create mode 100644 20240111/man-in-the-middle.txt
create mode 100644 20240111/random-01.c
create mode 100644 20240111/random-02.c
create mode 100644 20240111/random-03.c
create mode 100644 20240111/random-04.c
diff --git a/20240111/diffie-hellman.txt b/20240111/diffie-hellman.txt
new file mode 100644
index 0000000..1f56ea1
--- /dev/null
+++ b/20240111/diffie-hellman.txt
@@ -0,0 +1,14 @@
+Diffie-Hellman-Schlüsselaustausch
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Alice Bob
+
+ <------ gemeinsam: e --->
+
+geheim: a geheim: b
+
+ A = e^a -------------->
+
+ <-------------------- B = e^b
+
+B^a = e^(b·a) A^b = e^(a·b)
+ ~~~~~~~ ~~~~~~~ <----- gemeinsamer geheimer Schlüssel
diff --git a/20240111/hashes-01.txt b/20240111/hashes-01.txt
new file mode 100644
index 0000000..c19ab40
--- /dev/null
+++ b/20240111/hashes-01.txt
@@ -0,0 +1,10 @@
+cassini/home/peter/bo/2023ws/dbs/20240111> sha256sum
+Hallo. Dies ist ein Test.
+565fd769eb3b7df2c4f6e65f4ed8cc977d93d6eebcea67b1de09cbad37911521 -
+cassini/home/peter/bo/2023ws/dbs/20240111> sha256sum
+Hallo. Dies ist ein Test.
+565fd769eb3b7df2c4f6e65f4ed8cc977d93d6eebcea67b1de09cbad37911521 -
+cassini/home/peter/bo/2023ws/dbs/20240111> sha256sum
+Hallo. Dies ist ein test.
+f6d865709ef59cb882ad71695a7af2a248040a8d44856bfc84a0821f71070af7 -
+cassini/home/peter/bo/2023ws/dbs/20240111>
diff --git a/20240111/mac-01.txt b/20240111/mac-01.txt
new file mode 100644
index 0000000..e757dd9
--- /dev/null
+++ b/20240111/mac-01.txt
@@ -0,0 +1,9 @@
+Message Authentication Code (MAC)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Nachricht: Dies ist ein Test.
+
+Hash-Wert: 8a8c0ba357659d8ad10cc6c79048a07b440c053c50a1a83466440e5a22a319e0
+
+mit geheimem Schlüssel verschlüsseln --> MAC
+
+Empfänger kennt denselben geheimen Schlüssel --> entschlüsseln, mit Hash vergleichen
diff --git a/20240111/man-in-the-middle.txt b/20240111/man-in-the-middle.txt
new file mode 100644
index 0000000..ce21bc6
--- /dev/null
+++ b/20240111/man-in-the-middle.txt
@@ -0,0 +1,41 @@
+Diffie-Hellman-Schlüsselaustausch
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Alice Bob
+
+ <------ gemeinsam: e --->
+
+geheim: a geheim: b
+
+ A = e^a -------------->
+
+ <-------------------- B = e^b
+
+B^a = e^(b·a) A^b = e^(a·b)
+ ~~~~~~~ ~~~~~~~ <----- gemeinsamer geheimer Schlüssel
+
+Man-In-The-Middle-Angriff
+~~~~~~~~~~~~~~~~~~~~~~~~~
+Alice Mallory Bob
+
+ <------ gemeinsam: e---------> <------------ gemeinsam ------->
+
+geheim: a m geheim: b
+
+ A = e^a --------------------> A m ---------------------------->
+
+ <----------------------- M = e^m B <------------------------- B = e^b
+
+M^a = e^(m·a) M^b = e^(m·b)
+
+Gegenmaßnahme: Sorgfalt beim Schlüsselaustausch
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Öffentlicher Schlüssel von Alice an Bob:
+
+Alice Bob
+
+ A = e^a -------------->
+
+Hash-Wert des Schlüssels ("Fingerprint") über separaten Kanal austauschen
+z.B. Telefonat: Stimme erkennen -- Achtung: KI kann Stimme fälschen
+z.B. Visitenkarte
diff --git a/20240111/random-01.c b/20240111/random-01.c
new file mode 100644
index 0000000..a3a48cf
--- /dev/null
+++ b/20240111/random-01.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+ for (int i = 0; i < 10; i++)
+ printf ("%d ", rand ());
+ printf ("\n");
+ return 0;
+}
diff --git a/20240111/random-02.c b/20240111/random-02.c
new file mode 100644
index 0000000..dd8a2e8
--- /dev/null
+++ b/20240111/random-02.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+ for (int i = 0; i < 10; i++)
+ printf ("%d ", rand () % 26);
+ printf ("\n");
+ return 0;
+}
diff --git a/20240111/random-03.c b/20240111/random-03.c
new file mode 100644
index 0000000..6f32d19
--- /dev/null
+++ b/20240111/random-03.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main (void)
+{
+ srand (42);
+ for (int i = 0; i < 10; i++)
+ printf ("%d ", rand () % 26);
+ printf ("\n");
+ return 0;
+}
diff --git a/20240111/random-04.c b/20240111/random-04.c
new file mode 100644
index 0000000..f1d3228
--- /dev/null
+++ b/20240111/random-04.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main (void)
+{
+ srand (getpid ());
+ for (int i = 0; i < 10; i++)
+ printf ("%d ", rand () % 26);
+ printf ("\n");
+ return 0;
+}
--
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