Hex to ASCII to Binary

[DeathLeap]

I want to make two functions.

The first function converts Hex to ASCII
the second function converts ASCII to Binary

I think I already got the first function to work. But when I try to compare the output of my program with some output from a website that I am using, they don't match.

  #include <iostream>
#include <string>
#include <vector>

using namespace std;

string hexToAscii(string c)
{
	int length = c.length();
	string newString;
	for (int i = 0; i < length; i+=2)
	{
		string byte = c.substr(i, 2);
		char chr = (char)(int)strtol(byte.c_str(), NULL, 16);
		newString.push_back(chr);
	}
	return newString;
}

int main()
{
	//ciphertexts 
	string c1 = "315c4eeaa8b5f8aaf9174145bf43e1784b8fa00dc71d885a804e5ee9fa40b16349c146fb778cdf2d3aff021dfff5b403b510d0d0455468aeb98622b137dae857553ccd8883a7bc37520e06e515d22c954eba5025b8cc57ee59418ce7dc6bc41556bdb36bbca3e8774301fbcaa3b83b220809560987815f65286764703de0f3d524400a19b159610b11ef3e";
	string c2 = "234c02ecbbfbafa3ed18510abd11fa724fcda2018a1a8342cf064bbde548b12b07df44ba7191d9606ef4081ffde5ad46a5069d9f7f543bedb9c861bf29c7e205132eda9382b0bc2c5c4b45f919cf3a9f1cb74151f6d551f4480c82b2cb24cc5b028aa76eb7b4ab24171ab3cdadb8356f";
	string c3 = "32510ba9a7b2bba9b8005d43a304b5714cc0bb0c8a34884dd91304b8ad40b62b07df44ba6e9d8a2368e51d04e0e7b207b70b9b8261112bacb6c866a232dfe257527dc29398f5f3251a0d47e503c66e935de81230b59b7afb5f41afa8d661cb";
	string c4 = "32510ba9aab2a8a4fd06414fb517b5605cc0aa0dc91a8908c2064ba8ad5ea06a029056f47a8ad3306ef5021eafe1ac01a81197847a5c68a1b78769a37bc8f4575432c198ccb4ef63590256e305cd3a9544ee4160ead45aef520489e7da7d835402bca670bda8eb775200b8dabbba246b130f040d8ec6447e2c767f3d30ed81ea2e4c1404e1315a1010e7229be6636aaa";
	string c5 = "3f561ba9adb4b6ebec54424ba317b564418fac0dd35f8c08d31a1fe9e24fe56808c213f17c81d9607cee021dafe1e001b21ade877a5e68bea88d61b93ac5ee0d562e8e9582f5ef375f0a4ae20ed86e935de81230b59b73fb4302cd95d770c65b40aaa065f2a5e33a5a0bb5dcaba43722130f042f8ec85b7c2070";
	string c6 = "32510bfbacfbb9befd54415da243e1695ecabd58c519cd4bd2061bbde24eb76a19d84aba34d8de287be84d07e7e9a30ee714979c7e1123a8bd9822a33ecaf512472e8e8f8db3f9635c1949e640c621854eba0d79eccf52ff111284b4cc61d11902aebc66f2b2e436434eacc0aba938220b084800c2ca4e693522643573b2c4ce35050b0cf774201f0fe52ac9f26d71b6cf61a711cc229f77ace7aa88a2f19983122b11be87a59c355d25f8e4";
	string c7 = "32510bfbacfbb9befd54415da243e1695ecabd58c519cd4bd90f1fa6ea5ba47b01c909ba7696cf606ef40c04afe1ac0aa8148dd066592ded9f8774b529c7ea125d298e8883f5e9305f4b44f915cb2bd05af51373fd9b4af511039fa2d96f83414aaaf261bda2e97b170fb5cce2a53e675c154c0d9681596934777e2275b381ce2e40582afe67650b13e72287ff2270abcf73bb028932836fbdecfecee0a3b894473c1bbeb6b4913a536ce4f9b13f1efff71ea313c8661dd9a4ce";
	string c8 = "315c4eeaa8b5f8bffd11155ea506b56041c6a00c8a08854dd21a4bbde54ce56801d943ba708b8a3574f40c00fff9e00fa1439fd0654327a3bfc860b92f89ee04132ecb9298f5fd2d5e4b45e40ecc3b9d59e9417df7c95bba410e9aa2ca24c5474da2f276baa3ac325918b2daada43d6712150441c2e04f6565517f317da9d3";
	string c9 = "271946f9bbb2aeadec111841a81abc300ecaa01bd8069d5cc91005e9fe4aad6e04d513e96d99de2569bc5e50eeeca709b50a8a987f4264edb6896fb537d0a716132ddc938fb0f836480e06ed0fcd6e9759f40462f9cf57f4564186a2c1778f1543efa270bda5e933421cbe88a4a52222190f471e9bd15f652b653b7071aec59a2705081ffe72651d08f822c9ed6d76e48b63ab15d0208573a7eef027";
	string c10 = "466d06ece998b7a2fb1d464fed2ced7641ddaa3cc31c9941cf110abbf409ed39598005b3399ccfafb61d0315fca0a314be138a9f32503bedac8067f03adbf3575c3b8edc9ba7f537530541ab0f9f3cd04ff50d66f1d559ba520e89a2cb2a83";
	
	string target = "32510ba9babebbbefd001547a810e67149caee11d945cd7fc81a05e9f85aac650e9052ba6a8cd8257bf14d13e6f0a803b54fde9e77472dbff89d71b57bddef121336cb85ccb8f3315f4b52e301d16e9f52f904";

	string cipher = hexToAscii(c10);
	cout << cipher << endl;

	getchar();
	return 0;
}

[integralfx]

The first function converts Hex to ASCII

ASCII is a system used for the representation of characters. What do you mean by converting hex to ASCII?

[DeathLeap]

Do you see the strings I have in my int main? Those are hex-encoded strings. I want to represent them in ASCII.

[integralfx]

Those are hex-encoded strings. I want to represent them in ASCII.

So how do you convert a hexadecimal string into ASCII? What's 0x64 in ASCII?

[DeathLeap]

it's the character d?

Okay I get your point now. I want to convert a hexadecimal string into characters.

[integralfx]

Okay, I understand now. What's your expected output with c10 as the argument? It should be a garbage string as not all characters are printable. My output is:

Fm�阷��FO�,�vAݪ<��A�
��	�9Y��9�ϯ�&������2P;��g�:��W\;�ܛ��7SA��<�O�f��Y�R���*�

[DeathLeap]

I changed the function.

When I test c10, I get this:

Fm∞Θÿ╖ó√FOφ,φvA▌¬<├ÖA╧
f±╒Y║Rëó╦*â│9£╧»╢&ⁿáú╛èƒ2P;φ¼Çg≡:█≤W\;Ä▄¢º⌡7SA½ƒ<╨O⌡

However, if I take that hex ciphertext to a converter such as:
http://string-functions.com/hex-string.aspx

I get this result:

Fmì阷¢ûFOí,ívAݪ<ÙAÏ
»ô	í9Y€³9œÏ¯¶&ü £¾ŠŸ2P;í¬€gð:ÛóW\;ŽÜ›§õ7SA«Ÿ<ÐOõ
fñÕYºR‰¢Ë*ƒ

There are differences. So the function I am using is not working properly, or is it just not printing it as I see it in command prompt?

#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <stdexcept>
#include <algorithm>

using namespace std;

string hex_to_string(const std::string& in) {
	std::string output;

	if ((in.length() % 2) != 0) {
		throw std::runtime_error("String is not valid length ...");
	}

	size_t cnt = in.length() / 2;

	for (size_t i = 0; cnt > i; ++i) {
		uint32_t s = 0;
		std::stringstream ss;
		ss << std::hex << in.substr(i * 2, 2);
		ss >> s;

		output.push_back(static_cast<unsigned char>(s));
	}

	return output;
}

int main()
{
	//vector<unsigned char>vec;
	string output;
	//ciphertexts 
	string c1 = "315c4eeaa8b5f8aaf9174145bf43e1784b8fa00dc71d885a804e5ee9fa40b16349c146fb778cdf2d3aff021dfff5b403b510d0d0455468aeb98622b137dae857553ccd8883a7bc37520e06e515d22c954eba5025b8cc57ee59418ce7dc6bc41556bdb36bbca3e8774301fbcaa3b83b220809560987815f65286764703de0f3d524400a19b159610b11ef3e";
	string c2 = "234c02ecbbfbafa3ed18510abd11fa724fcda2018a1a8342cf064bbde548b12b07df44ba7191d9606ef4081ffde5ad46a5069d9f7f543bedb9c861bf29c7e205132eda9382b0bc2c5c4b45f919cf3a9f1cb74151f6d551f4480c82b2cb24cc5b028aa76eb7b4ab24171ab3cdadb8356f";
	string c3 = "32510ba9a7b2bba9b8005d43a304b5714cc0bb0c8a34884dd91304b8ad40b62b07df44ba6e9d8a2368e51d04e0e7b207b70b9b8261112bacb6c866a232dfe257527dc29398f5f3251a0d47e503c66e935de81230b59b7afb5f41afa8d661cb";
	string c4 = "32510ba9aab2a8a4fd06414fb517b5605cc0aa0dc91a8908c2064ba8ad5ea06a029056f47a8ad3306ef5021eafe1ac01a81197847a5c68a1b78769a37bc8f4575432c198ccb4ef63590256e305cd3a9544ee4160ead45aef520489e7da7d835402bca670bda8eb775200b8dabbba246b130f040d8ec6447e2c767f3d30ed81ea2e4c1404e1315a1010e7229be6636aaa";
	string c5 = "3f561ba9adb4b6ebec54424ba317b564418fac0dd35f8c08d31a1fe9e24fe56808c213f17c81d9607cee021dafe1e001b21ade877a5e68bea88d61b93ac5ee0d562e8e9582f5ef375f0a4ae20ed86e935de81230b59b73fb4302cd95d770c65b40aaa065f2a5e33a5a0bb5dcaba43722130f042f8ec85b7c2070";
	string c6 = "32510bfbacfbb9befd54415da243e1695ecabd58c519cd4bd2061bbde24eb76a19d84aba34d8de287be84d07e7e9a30ee714979c7e1123a8bd9822a33ecaf512472e8e8f8db3f9635c1949e640c621854eba0d79eccf52ff111284b4cc61d11902aebc66f2b2e436434eacc0aba938220b084800c2ca4e693522643573b2c4ce35050b0cf774201f0fe52ac9f26d71b6cf61a711cc229f77ace7aa88a2f19983122b11be87a59c355d25f8e4";
	string c7 = "32510bfbacfbb9befd54415da243e1695ecabd58c519cd4bd90f1fa6ea5ba47b01c909ba7696cf606ef40c04afe1ac0aa8148dd066592ded9f8774b529c7ea125d298e8883f5e9305f4b44f915cb2bd05af51373fd9b4af511039fa2d96f83414aaaf261bda2e97b170fb5cce2a53e675c154c0d9681596934777e2275b381ce2e40582afe67650b13e72287ff2270abcf73bb028932836fbdecfecee0a3b894473c1bbeb6b4913a536ce4f9b13f1efff71ea313c8661dd9a4ce";
	string c8 = "315c4eeaa8b5f8bffd11155ea506b56041c6a00c8a08854dd21a4bbde54ce56801d943ba708b8a3574f40c00fff9e00fa1439fd0654327a3bfc860b92f89ee04132ecb9298f5fd2d5e4b45e40ecc3b9d59e9417df7c95bba410e9aa2ca24c5474da2f276baa3ac325918b2daada43d6712150441c2e04f6565517f317da9d3";
	string c9 = "271946f9bbb2aeadec111841a81abc300ecaa01bd8069d5cc91005e9fe4aad6e04d513e96d99de2569bc5e50eeeca709b50a8a987f4264edb6896fb537d0a716132ddc938fb0f836480e06ed0fcd6e9759f40462f9cf57f4564186a2c1778f1543efa270bda5e933421cbe88a4a52222190f471e9bd15f652b653b7071aec59a2705081ffe72651d08f822c9ed6d76e48b63ab15d0208573a7eef027";
	string c10 = "466d06ece998b7a2fb1d464fed2ced7641ddaa3cc31c9941cf110abbf409ed39598005b3399ccfafb61d0315fca0a314be138a9f32503bedac8067f03adbf3575c3b8edc9ba7f537530541ab0f9f3cd04ff50d66f1d559ba520e89a2cb2a83";

	string target = "32510ba9babebbbefd001547a810e67149caee11d945cd7fc81a05e9f85aac650e9052ba6a8cd8257bf14d13e6f0a803b54fde9e77472dbff89d71b57bddef121336cb85ccb8f3315f4b52e301d16e9f52f904";

	output = hex_to_string(c1);
	cout << output;

	getchar();
	return 0;
}

[Thomas1965]

output.push_back(static_cast<unsigned char>(s));
for values > 127 (0x7F) you will get an overflow.

[jonnin]

sprint(stringvar, "%x", int);

a lookup table of strings for 0-15 for binary is the way to get binary text in and out. Binary and hex have a relationship: each hex digit is 4 binary digits.
0 = 0000 = 0x00
1 = 0001 = 0x01
2 = 0010 = 0x02
3 = 0011 = 0x03
...
15 = 1111 = 0x0F

you can also do conversions to and from binary with the shift operator (>>).

13 >> 1 shifts the bits of 13 one place. Modulo 2 and stuff can peel it apart.

You can also use base 2 and logs. if you didn't know log is base 10, lg is base 2, ln is base e. But I don't think c++ has lg, you have to do change of base trick.

I am assuming you want binary text here (0B11010101100 format stuff)
not binary in the usual sense of the term (computer formatted numbers, which simply contain the value of the data). You can't meaningfully print computer formatted data, you want to convert back to hex, base10, text, or something useful.

sscanf can reverse hex into a number. But for these huge values, you need a big-int class that supports it or roll your own.

[dhayden]

Consider how to do this by hand first. Take the 1st 4 characters in your hex string: 315c. This represents 2 ASCII characters.

The first string is represented by "31". This means that the ASCII value is 3*16+1. So to convert it the ASCII string "31" to the right ASCII value, you must:
- convert ASCII '3' to the number 3.
- convert ASCII '1' to the number 1.
- compute 3*16+1.

For the second pair of numbers, you have to do something similar:
- Convert ASCII '5' to the number 5.
- Convert ASCII 'c' to the number 12.
- Compute 5*16+12