feat: a2 c

.gitignore

@@ -1 +1,3 @@
 *.pdf
+sheet01/a2/Hash.java
+*.class

sheet01/a2/b-sha3.txt

@@ -0,0 +1 @@
+SHA3-256 (plaintext.txt) = 8cdcfd9d0414adbba1bb146c214e181d7e5d7c8edde90b79dcb27df005fcc298

sheet01/a2/b.txt

@@ -1,2 +1,4 @@
-plaintext.txt -Algorithm SHA256
-reads the plaintext file and calculates a unique hash string using the SHA-256 cryptographic algorithm.
+cksum -a sha2 --length 256 plaintext.txt > b-sha2.txt
+reads the plaintext file and calculates a unique hash string using the SHA2-256 cryptographic algorithm and writes it into b-sha2.txt
+cksum -a sha3 --length 256 plaintext.txt > b-sha3.txt
+reads the plaintext file and calculates a unique hash string using the SHA3-256 cryptographic algorithm and writes it into b-sha3.txt

sheet01/a2/c-hash.txt

@@ -0,0 +1 @@
+03087115

sheet01/a2/c.txt

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+javac Hash.java  (Compiles the java class)
+java Hash plaintext.txt  (runs the custom Hash function on the text file)
+    Output: 03087115

sheet01/a2/d.txt

@@ -0,0 +1,29 @@
+The custom hash is adding the unicode values of each character, the amount of rows and the amount of characters each multiplied with a hex value.
+This leads to it giving the same output when switching around rows, or even putting all characters into one line and adding the required amount of empty lines behind that. 
+
+
+"""
+LJVeuiolknitaaornrdia
+
+
+"""
+
+is producing the same hash as
+
+"""
+Leonard
+Viktoria
+Julian
+"""
+
+and the same as
+
+"""
+Julian
+Leonard
+Viktoria
+"""
+
+It has a good enough "first pre-image resistance" since it is not really possible to find the correct characters in the same order from the hash value that give the same original file
+The "second pre-image resistance" is weak since you can easily calculate a different file which gives the same output.
+It has no collision resistance since you can just switch around characters and get the same hash.

sheet02/a1/b-aeskey.txt

@@ -0,0 +1,2 @@
+AES Key: cddf0c7f664624fd0b604c622a2c670dffc3fdd7859a7cdd2377d1ba2ab86f89
+IV: 30579741743af76bdd06ec45b12ee6d7

sheet02/a1/b-dec-aes.txt

@@ -0,0 +1,3 @@
+Viktoria
+Leo
+Julian

sheet02/a1/b-enc-aes.txt

@@ -0,0 +1 @@
+o5Ö¦Íß*òþk‚¼¾I¦BîÜr<C39C>Œ´<C592>6@hün5Ø

sheet02/a1/b.txt

@@ -0,0 +1,5 @@
+Generate 256bit aes key and 128 bit iv:
+openssl rand -hex 32
+openssl rand -hex 16
+Encrypt the file plaintext.txt with the key and iv
+openssl enc -aes-256-cbc -in plaintext.txt -out b-enc-aes.txt -K cddf0c7f664624fd0b604c622a2c670dffc3fdd7859a7cdd2377d1ba2ab86f89 -iv 30579741743af76bdd06ec45b12ee6d7

sheet02/a1/c-dec-rsa.txt

@@ -0,0 +1,3 @@
+Viktoria
+Leo
+Julian

sheet02/a1/c-enc-rsa.txt

@@ -0,0 +1,2 @@
+’Ìnç‰á~Á>hì`£aÿ*‘Ú#ÒÒh‹å4ò,>«ôÓ„ì÷9&†…%´c,¤tNØR‰“5sŠq
+˜°+$úd!E½Í·‘3£y£<79>3Ÿ|#Ù2ÒÈ„¬ÜºÕLÍ^é¢L9ÊApØîfDV<44>kX´¨^æeh\É£H
«~y	ƵýdÀK½I\€óf>I5EÿcÛ,‹I+s<>

sheet02/a1/c-rsa-priv.key

@@ -0,0 +1,28 @@
+-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----

sheet02/a1/c-rsa-pub.key

@@ -0,0 +1,9 @@
+-----BEGIN PUBLIC KEY-----
+MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtUuuBB1nIjypPupE1d0B
+nve6BrDuKQG3gL6qsxbTrpZCMtXBGJUCD/iHvSy9YtbTo5MfL949BaKu0w0JMAqU
+6HSUZedITnYznYXIxDVNRqGdsR2G/rDcLlaO0c5fKxD/fadTfbJWqv3eC41eHOj1
+g43drxsXJz6YoWLWToKu1zTdNuiLvhN7+8/DAHDMctkQEMsNj3qoMScMoT4NROrM
++Do51EDoUtJ8Ks9l8Bvlz3x/MrX9140Dy571LZiLHD9VuMI3iQybr8puaaq/Da+9
+co2C5vbXn0CzjR8V1DibsYiWrSY/TOcirOmf4AdkUQNumrOsMiLkOlhbuB061K4H
+awIDAQAB
+-----END PUBLIC KEY-----

sheet02/a1/c.txt

@@ -0,0 +1,8 @@
+Generate rsa private key:
+openssl genpkey -algorithm RSA -out c-rsa-priv.key -pkeyopt rsa_keygen_bits:2048
+
+Extract the public key from the private key
+openssl pkey -in c-rsa-priv.key -pubout -out c-rsa-pub.key
+
+Encrypt the file using the rsa pubkey
+openssl pkeyutl -encrypt -pubin -inkey c-rsa-pub.key -in plaintext.txt -out c-enc-rsa.txt

sheet02/a1/e.txt

@@ -0,0 +1,9 @@
+Decrypt the aes-encrypted key with the aes-key and iv:
+openssl enc -d -aes-256-cbc -in b-enc-aes.txt -out b-dec-aes.txt -K cddf0c7f664624fd0b604c622a2c670dffc3fdd7859a7cdd2377d1ba2ab86f89 -iv 30579741743af76bdd06ec45b12ee6d7
+
+Decrypt encrypted file using the rsa private key
+openssl pkeyutl -decrypt -inkey a1/c-rsa-priv.key -in a1/c-enc-rsa.txt -out a1/c-dec-rsa.txt
+
+Verify the same files with the tool diff
+diff plaintext.txt b-dec-aes.txt  -> Prints nothing, so its the same
+diff plaintext.txt c-dec-rsa.txt  -> Prints nothing, so its the same

sheet02/a1/plaintext.txt

@@ -0,0 +1,3 @@
+Viktoria
+Leo
+Julian

sheet02/a2/SignECDSA.java

@@ -0,0 +1,23 @@
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.security.KeyPairGenerator;
+import java.security.Signature;
+import java.util.Base64;
+
+public class SignECDSA {
+    public static void main(String[] args) throws Exception {
+        final var gen = KeyPairGenerator.getInstance("EC");
+        final var kp = gen.genKeyPair();
+
+        final var bytes = Files.readAllBytes(Path.of("plaintext.txt"));
+        final var sig = Signature.getInstance("SHA256withECDSA");
+        sig.initVerify(kp.getPublic());
+        sig.initSign(kp.getPrivate());
+        sig.update(bytes);
+        final var signature = sig.sign();
+
+        Files.write(Path.of("b-signature.txt"), Base64.getEncoder().encode(signature));
+        Files.write(Path.of("b-publickey.txt"), Base64.getEncoder().encode(kp.getPublic().getEncoded()));
+        Files.write(Path.of("b-privatekey.txt"), Base64.getEncoder().encode(kp.getPrivate().getEncoded()));
+    }
+}

sheet02/a2/VerifyECDSA.java

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+import java.security.KeyFactory;
+import java.security.Signature;
+import java.security.spec.X509EncodedKeySpec;
+import java.util.Base64;
+
+public class VerifyECDSA {
+    public static void main(String[] args) throws Exception {
+        if (args.length < 3) {
+            System.out.println(
+                    "Please specify in the following order: Public Key (X509), Signature (Base64), Message (plain text)");
+            return;
+        }
+
+        final String PUBLIC_KEY = args[0];
+        final String SIGNATURE = args[1];
+        final String MESSAGE = args[2];
+
+        final var kf = KeyFactory.getInstance("EC");
+        final var pub = kf.generatePublic(new X509EncodedKeySpec(Base64.getDecoder().decode(PUBLIC_KEY)));
+
+        final var sig = Signature.getInstance("SHA256withECDSA");
+        sig.initVerify(pub);
+        sig.update(MESSAGE.getBytes());
+        System.out.println("Correct: " + sig.verify(Base64.getDecoder().decode(SIGNATURE)));
+    }
+}

sheet02/a2/b-privatekey.txt

@@ -0,0 +1 @@
+ME4CAQAwEAYHKoZIzj0CAQYFK4EEACIENzA1AgEBBDA/BgxBUzJUc3MfZVBIdPTbQfIdf4SABYZJlno8rUPkhBRrK3VkpEhyGdviYUPViz4=

sheet02/a2/b-publickey.txt

@@ -0,0 +1 @@
+MHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEVHteuMnscItIHycwEZ80P44WyIWmL7PmeN6HLRAu8IJsLKX6BTDawN0MezskF68oQ9Ft7zy2u4v2aaYB4tgUv+0YG7zEwFr0ofqSqFFPSLr0qrVRvXi/H7Bux8tYVgaN

sheet02/a2/b-signature.txt

@@ -0,0 +1 @@
+MGQCMHq04CPgDiSaWPXb3LiuBrb97aV4JjinA5gIuEIFjFYLD1jYdECBdV/aHLLYsyMYnAIwedsP6qJKK4Y2uLgn3XLxbHgDKxf+eq07Rptmn/LttHTpWjtTfaLERM+Uh2BUGmMt

sheet02/a2/c.txt

@@ -0,0 +1,5 @@
+copy the publickey into a .pem file that starts with -----BEGIN PUBLIC KEY----- and ends with -----END PUBLIC KEY----- and has linebreaks after 64 chars.
+then decode the base64 signature
+base64 -d b-signature.txt > signature.bin
+verify using openssl
+openssl dgst -sha256 -verify c-pubkey.pem -signature signature.bin plaintext.txt 

sheet02/a2/plaintext.txt

@@ -0,0 +1,3 @@
+Julian
+Leonard
+Viktoria

sheet02/a2/verify-example.sh

@@ -0,0 +1 @@
+java VerifyECDSA.java "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEnSgO/uuSq9QHH/rrnSgXeQTKPMI8tjLhyJzevl9fLQZW/zXuHk9iThiKY/c2k52quUby3czAwL2l2HaRqcBXEg==" "MEUCIAzRvK3CNFqMTZxIgMd1uQ/XybtRKXFht9S4q8qUy/IbAiEA7EcFYuRbViVC/zzIRW78HekjRHZVn3DjHVUcKyJ5sXw=" "hello world"