C ++处理非常大的整数 [英] C++ handling very large integers

问题描述

我使用RSA算法进行加密/解密，为了解密文件，你必须处理一些很大的值。具体来说，

  P = C ^ d％n 
 = 62 ^ 65％133 
  

现在这是真正的唯一的计算。我尝试使用Matt McCutchen的BigInteger库，但是我在链接过程中遇到很多编译错误，例如：

 加密。 o（.text + 0x187）：encryption.cpp：未定义引用`BigInteger :: BigInteger（int）'
 
 encryption.o（.text + 0x302）：encryption.cpp：undefined引用` operator<<<<<（std :: ostream&），BigInteger const&）'
 
 encryption.o（.text $ _ZNK10BigIntegermlERKS_ [BigInteger :: operator *（BigInteger const& .cpp：未定义引用`BigInteger :: multiply（BigInteger const& BigInteger const&）'
  

所以我想知道什么是处理RSA算法产生的真正大整数的最好方法。

我听说一个可能性是声明你的变量为双长，所以...

  long long decryptedCharacter; 
  

但我不知道可以存储的整数有多大。

---

例如，我尝试使用dev C ++编译和运行以下程序：

  #include iostream 
 
 #includebigint \BigIntegerLibrary.hh
 
 using namespace std; 
 
 int main（）
 {
 BigInteger a = 65536; 
 cout<< （a * a * a * a * a * a * a * a）; 
 return 0; 
} 
  

那么我会得到这些错误。

Derek，我认为通过包含 BigIntegerLibrary.hh 文件，编译器会通过并编译它将使用的所有必需的文件。 p>

如何尝试编译上述程序以解决链接错误？

解决方案

元回答：

如果你使用一个库进行bigint运算，那么问自己为什么你不使用库RSA实施。

例如， http：// www。 gnu.org/software/gnu-crypto/ 包含RSA实施。它与GMP具有相同的许可证。

但是，他们没有与相同的许可证http://mattmccutchen.net/bigint/ ，我似乎已被放入美国的公共领域。

I am using the RSA Algorithm for encryption/decryption, and in order to decrypt the files you have to deal with some pretty big values. More specifically, things like

P = C^d % n
  = 62^65 % 133

Now that is really the only calculations that ill be doing. I have tried using Matt McCutchen's BigInteger Library, but I am getting a lot of compiler errors during linking, such as:

encryption.o(.text+0x187):encryption.cpp: undefined reference to `BigInteger::BigInteger(int)'

encryption.o(.text+0x302):encryption.cpp: undefined reference to `operator<<(std::ostream&, BigInteger const&)'

encryption.o(.text$_ZNK10BigIntegermlERKS_[BigInteger::operator*(BigInteger const&) const]+0x63):encryption.cpp: undefined reference to `BigInteger::multiply(BigInteger const&, BigInteger const&)'

So I was wondering what would be the best way to go about handling the really big integers that come out of the RSA Algorithm.

I heard that a possibility would be to declare your variables as a double long, so...

long long decryptedCharacter;

but I'm not sure exactly how big of an integer that can store.

---

Well for example, I try to compile and run the following program using dev C++:

#include iostream

#include "bigint\BigIntegerLibrary.hh"

using namespace std;

int main()
{
    BigInteger a = 65536;
    cout << (a * a * a * a * a * a * a * a);
    return 0;
}

then I get those errors.

Derek, I thought that by including the BigIntegerLibrary.hh file, that the compiler would go through and compile all the necessary files that it will use.

How should I try and compile the program above in order to resolve the linking errors?

解决方案

Meta-answer:

If you're using a library for the bigint arithmetic, then ask yourself why you aren't using a library for the whole RSA implementation.

For example, http://www.gnu.org/software/gnu-crypto/ contains an RSA implementation. It has the same license as GMP.

However, they do not have the same license as http://mattmccutchen.net/bigint/, which appears to me to have been placed into the public domain in the US.

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