Initial commit

.gitignore

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+brute
+shift
+count
+vigenere

Makefile

@@ -0,0 +1,11 @@
+all: shift brute count vigenere
+shift: shift.cc
+	g++ shift.cc -o shift
+brute: brute.cc
+	g++ brute.cc -o brute
+count: count.cc
+	g++ count.cc -o count -std=c++20
+vigenere: vigenere.cc
+	g++ vigenere.cc -o vigenere
+clean:
+	rm shift brute

brute.cc

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+#include <iostream>
+
+void shift(char* text, int key)
+{
+	std::cout << key << ": ";
+	for(int i = 0; text[i] != 0; ++i)
+	{
+		char c = text[i]-key;
+		if(c < 'a') c+=26;
+		if(c > 'z') c-=26;
+		std::cout << c;
+	}
+	std::cout << std::endl;
+}
+int main(int argc, char** argv)
+{
+	if(argc < 2)
+	{
+		std::cout << "Usage: " << argv[0] << " <ciphertext>" << std::endl;
+		return 0;
+	}
+	for(int i = 1; i < 26; ++i)
+	{
+		shift(argv[1], i);
+	}
+	return 0;
+}

count.cc

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+#include <map>
+#include <iostream>
+
+int main(int argc, char** argv)
+{
+	if(argc < 2)
+	{
+		std::cout << "Usage: " << argv[0] << " <ciphertext>" << std::endl;
+		return 0;
+	}
+	char* ciphertext = argv[1];
+	std::map<char, int> letters;
+
+	for(int i = 0; ciphertext[i] != 0; ++i)
+	{
+		if(letters.contains(ciphertext[i]))
+		{
+			letters[ciphertext[i]]++;
+		}
+		else
+		{
+			letters[ciphertext[i]] = 1;
+		}
+	}
+	for(auto& [key, value] : letters)
+	{
+		std::cout << key << ": " << value << std::endl;
+	}
+	return 0;
+}

shift.cc

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+#include <iostream>
+
+int main(int argc, char** argv)
+{
+	char* text;
+	int key;
+	if(argc < 3)
+	{
+		std::cout << "Usage: " << argv[0] << " <plain text> <key>" << std::endl;
+		return 0;
+	}
+	text = argv[1];
+	key = atoi(argv[2]);
+	
+	for(int i = 0; text[i] != 0; ++i)
+	{
+		char c = text[i]+key;
+		if(c < 'a') c+=26;
+		if(c > 'z') c-=26;
+		std::cout << c;
+	}
+	std::cout << std::endl;
+	return 0;
+}

vigenere.cc

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+#include <iostream>
+
+int keyvalue(char c)
+{
+	return c - 'a';
+}
+int main(int argc, char** argv)
+{
+	char* text;
+	char* key;
+	if(argc < 3)
+	{
+		std::cout << "Usage: " << argv[0] << " <plain text> <key>" << std::endl;
+		return 0;
+	}
+
+	text = argv[1];
+	key = argv[2];
+
+	int ki = 0;
+	for(int pi = 0; text[pi] != 0; ++pi)
+	{
+		char c = text[pi] + keyvalue(key[ki]);
+		if(c < 'a') c+=26;
+		if(c > 'z') c-=26;
+		std::cout << c;
+		if(key[++ki] == 0) ki = 0;
+	}
+	std::cout << std::endl;
+	return 0;
+}