使用C++ WinAPI计算MD5哈希值

Question

我的C++应用需要计算MD5哈希值。目前，这是通过OpenSSL完成的，我想使用WinAPI - 以避免依赖外部库。

我编写了以下代码：

HCRYPTPROV hCryptProv = NULL;
HCRYPTHASH hHash = NULL;
HCRYPTHASH hHexHash = NULL;
HASH HA1;
HASHHEX HA1HEX;
DWORD data = HASHLEN;

// Get a handle to a cryptography provider context.
if(!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, 0))
{
    goto err;
}

// Acquire a hash object handle.
if(!CryptCreateHash(hCryptProv, CALG_MD5, 0, 0, &hHash))
{
    goto err;
}

CryptHashData(hHash, (const BYTE *)str, strlen(str), 0);

现在，奇怪的是有时可以正常工作，但有时CryptAcquireContext会返回NTE_BAD_KEYSET错误，这根据MSDN的说法是：

无法打开密钥容器。导致此错误的常见原因是密钥容器不存在。要创建密钥容器，请使用CRYPT_NEWKEYSET标志调用CryptAcquireContext。此错误代码还可能表明对现有密钥容器的访问被拒绝。通过使用CryptSetProvParam，密钥集创建者可以授予对该容器的访问权限。

现在我的问题是：

1. 如果我调用CryptSetProvParam，它具体做什么？一个简单的应用程序更改操作系统设置是正常的吗？
2. 有没有更简单的方法在C++ windows中计算MD5？

如果有人能给我好的建议，我将不胜感激。
谢谢。

- RRR

---

一个专门用于公共领域的实现可以在这里找到：http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5。 - Dave Rager

谢谢，但目前我更倾向于不自己实现它。 - RRR

您不需要亲自实现它。只需将md5.c和md5.h文件放入您的项目中并调用函数即可。 - Dave Rager

Answer 1

所以，我在这里找到了一个能够实现你想要的功能的例子。

看着他们的代码，我发现不同之处在于这一行：

他们的代码：CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)

你的代码：CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, 0)

因此，阅读标志的相关资料，我发现这样的信息:

CRYPT_VERIFYCONTEXT:此选项适用于使用临时密钥或不需要访问持久私有密钥的应用程序，例如仅执行哈希、加密和数字签名验证的应用程序。只有创建签名或解密消息的应用程序才需要访问私钥。在大多数情况下，应设置此标志。

http://msdn.microsoft.com/en-us/library/windows/desktop/aa379886%28v=vs.85%29.aspx

因此，你正在尝试访问你不需要的信息，所以请求被拒绝。最好的办法是通过包含该标志告诉Windows你不需要那些信息。

- Patrick M

Answer 2

我喜欢使用PROV_RSA_AES 和 CRYPT_VERIFYCONTEXT，因为它们支持大多数哈希函数。

以下是一个可行的示例：

#include <Wincrypt.h>

enum HashType
{
  HashSha1, HashMd5, HashSha256
};

std::string GetHashText( const void * data, const size_t data_size, HashType hashType )
{
  HCRYPTPROV hProv = NULL;

  if ( ! CryptAcquireContext( &hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT ) ) {
    return "";
  }

  BOOL hash_ok = FALSE;
  HCRYPTPROV hHash = NULL;
  switch ( hashType ) {
  case HashSha1 : hash_ok = CryptCreateHash( hProv, CALG_SHA1, 0, 0, &hHash ); break;
  case HashMd5 : hash_ok = CryptCreateHash( hProv, CALG_MD5, 0, 0, &hHash ); break;
  case HashSha256 : hash_ok = CryptCreateHash( hProv, CALG_SHA_256, 0, 0, &hHash ); break;
  }

  if ( ! hash_ok ) {
    CryptReleaseContext(hProv, 0);
    return "";
  }

  if ( ! CryptHashData( hHash, static_cast<const BYTE *>(data), data_size, 0 ) ) {
    CryptDestroyHash(hHash);
    CryptReleaseContext(hProv, 0);
    return "";
  }

  DWORD cbHashSize = 0, dwCount = sizeof(DWORD);
  if( ! CryptGetHashParam( hHash, HP_HASHSIZE, (BYTE *)&cbHashSize, &dwCount, 0 ) ) {
    CryptDestroyHash(hHash);
    CryptReleaseContext(hProv, 0);
    return "";
  }

  std::vector<BYTE> buffer( cbHashSize );
  if ( ! CryptGetHashParam( hHash, HP_HASHVAL, reinterpret_cast<BYTE*>( &buffer[0] ), &cbHashSize, 0) ) {
    CryptDestroyHash(hHash);
    CryptReleaseContext(hProv, 0);
    return "";
  }

  std::ostringstream oss;

  for ( std::vector<BYTE>::const_iterator iter = buffer.begin(); iter != buffer.end(); ++iter ) {
    oss.fill('0');
    oss.width(2);
    oss << std::hex << static_cast<const int>(*iter);
  }

  CryptDestroyHash(hHash);
  CryptReleaseContext(hProv, 0);
  return oss.str();
}

- Naszta

Answer 3

以下是可以创建的“MD5.h”文件和可使用的简单代码。

主.cpp

#include "md5.h"
int main()
{
MD5 md5;
puts( md5.digestString( "HELLO THERE I AM MD5!" ) ) ;
// print the digest for a binary file on disk.
puts( md5.digestFile( "C:\\WINDOWS\\notepad.exe" ) ) ;
return 0;
}

MD5.h

#ifndef MD5_H
#define MD5_H
#include <stdio.h>
#include <string.h>

#pragma region MD5 defines
// Constants for MD5Transform routine.
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

static unsigned char PADDING[64] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

// F, G, H and I are basic MD5 functions.
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

// ROTATE_LEFT rotates x left n bits.
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
// Rotation is separate from addition to prevent recomputation.
#define FF(a, b, c, d, x, s, ac) { \
  (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) { \
  (a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
      }
#define HH(a, b, c, d, x, s, ac) { \
  (a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
      }
#define II(a, b, c, d, x, s, ac) { \
  (a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
      }
#pragma endregion

typedef unsigned char BYTE;

// POINTER defines a generic pointer type
typedef unsigned char *POINTER;

// UINT2 defines a two byte word
typedef unsigned short int UINT2;

// UINT4 defines a four byte word
typedef unsigned long int UINT4;


// convenient object that wraps
// the C-functions for use in C++ only
class MD5
{
private:
    struct __context_t {
        UINT4 state[4];                                   /* state (ABCD) */
        UINT4 count[2];        /* number of bits, modulo 2^64 (lsb first) */
        unsigned char buffer[64];                         /* input buffer */
    } context;

#pragma region static helper functions
    // The core of the MD5 algorithm is here.
    // MD5 basic transformation. Transforms state based on block.
    static void MD5Transform(UINT4 state[4], unsigned char block[64])
    {
        UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

        Decode(x, block, 64);

        /* Round 1 */
        FF(a, b, c, d, x[0], S11, 0xd76aa478); /* 1 */
        FF(d, a, b, c, x[1], S12, 0xe8c7b756); /* 2 */
        FF(c, d, a, b, x[2], S13, 0x242070db); /* 3 */
        FF(b, c, d, a, x[3], S14, 0xc1bdceee); /* 4 */
        FF(a, b, c, d, x[4], S11, 0xf57c0faf); /* 5 */
        FF(d, a, b, c, x[5], S12, 0x4787c62a); /* 6 */
        FF(c, d, a, b, x[6], S13, 0xa8304613); /* 7 */
        FF(b, c, d, a, x[7], S14, 0xfd469501); /* 8 */
        FF(a, b, c, d, x[8], S11, 0x698098d8); /* 9 */
        FF(d, a, b, c, x[9], S12, 0x8b44f7af); /* 10 */
        FF(c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
        FF(b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
        FF(a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
        FF(d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
        FF(c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
        FF(b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

        /* Round 2 */
        GG(a, b, c, d, x[1], S21, 0xf61e2562); /* 17 */
        GG(d, a, b, c, x[6], S22, 0xc040b340); /* 18 */
        GG(c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
        GG(b, c, d, a, x[0], S24, 0xe9b6c7aa); /* 20 */
        GG(a, b, c, d, x[5], S21, 0xd62f105d); /* 21 */
        GG(d, a, b, c, x[10], S22, 0x2441453); /* 22 */
        GG(c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
        GG(b, c, d, a, x[4], S24, 0xe7d3fbc8); /* 24 */
        GG(a, b, c, d, x[9], S21, 0x21e1cde6); /* 25 */
        GG(d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
        GG(c, d, a, b, x[3], S23, 0xf4d50d87); /* 27 */
        GG(b, c, d, a, x[8], S24, 0x455a14ed); /* 28 */
        GG(a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
        GG(d, a, b, c, x[2], S22, 0xfcefa3f8); /* 30 */
        GG(c, d, a, b, x[7], S23, 0x676f02d9); /* 31 */
        GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

        /* Round 3 */
        HH(a, b, c, d, x[5], S31, 0xfffa3942); /* 33 */
        HH(d, a, b, c, x[8], S32, 0x8771f681); /* 34 */
        HH(c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
        HH(b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
        HH(a, b, c, d, x[1], S31, 0xa4beea44); /* 37 */
        HH(d, a, b, c, x[4], S32, 0x4bdecfa9); /* 38 */
        HH(c, d, a, b, x[7], S33, 0xf6bb4b60); /* 39 */
        HH(b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
        HH(a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
        HH(d, a, b, c, x[0], S32, 0xeaa127fa); /* 42 */
        HH(c, d, a, b, x[3], S33, 0xd4ef3085); /* 43 */
        HH(b, c, d, a, x[6], S34, 0x4881d05); /* 44 */
        HH(a, b, c, d, x[9], S31, 0xd9d4d039); /* 45 */
        HH(d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
        HH(c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
        HH(b, c, d, a, x[2], S34, 0xc4ac5665); /* 48 */

        /* Round 4 */
        II(a, b, c, d, x[0], S41, 0xf4292244); /* 49 */
        II(d, a, b, c, x[7], S42, 0x432aff97); /* 50 */
        II(c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
        II(b, c, d, a, x[5], S44, 0xfc93a039); /* 52 */
        II(a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
        II(d, a, b, c, x[3], S42, 0x8f0ccc92); /* 54 */
        II(c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
        II(b, c, d, a, x[1], S44, 0x85845dd1); /* 56 */
        II(a, b, c, d, x[8], S41, 0x6fa87e4f); /* 57 */
        II(d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
        II(c, d, a, b, x[6], S43, 0xa3014314); /* 59 */
        II(b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
        II(a, b, c, d, x[4], S41, 0xf7537e82); /* 61 */
        II(d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
        II(c, d, a, b, x[2], S43, 0x2ad7d2bb); /* 63 */
        II(b, c, d, a, x[9], S44, 0xeb86d391); /* 64 */

        state[0] += a;
        state[1] += b;
        state[2] += c;
        state[3] += d;

        // Zeroize sensitive information.
        memset((POINTER)x, 0, sizeof(x));
    }

    // Encodes input (UINT4) into output (unsigned char). Assumes len is
    // a multiple of 4.
    static void Encode(unsigned char *output, UINT4 *input, unsigned int len)
    {
        unsigned int i, j;

        for (i = 0, j = 0; j < len; i++, j += 4) {
            output[j] = (unsigned char)(input[i] & 0xff);
            output[j + 1] = (unsigned char)((input[i] >> 8) & 0xff);
            output[j + 2] = (unsigned char)((input[i] >> 16) & 0xff);
            output[j + 3] = (unsigned char)((input[i] >> 24) & 0xff);
        }
    }

    // Decodes input (unsigned char) into output (UINT4). Assumes len is
    // a multiple of 4.
    static void Decode(UINT4 *output, unsigned char *input, unsigned int len)
    {
        unsigned int i, j;

        for (i = 0, j = 0; j < len; i++, j += 4)
            output[i] = ((UINT4)input[j]) | (((UINT4)input[j + 1]) << 8) |
            (((UINT4)input[j + 2]) << 16) | (((UINT4)input[j + 3]) << 24);
    }
#pragma endregion


public:
    // MAIN FUNCTIONS
    MD5()
    {
        Init();
    }

    // MD5 initialization. Begins an MD5 operation, writing a new context.
    void Init()
    {
        context.count[0] = context.count[1] = 0;

        // Load magic initialization constants.
        context.state[0] = 0x67452301;
        context.state[1] = 0xefcdab89;
        context.state[2] = 0x98badcfe;
        context.state[3] = 0x10325476;
    }

    // MD5 block update operation. Continues an MD5 message-digest
    // operation, processing another message block, and updating the
    // context.
    void Update(
        unsigned char *input,   // input block
        unsigned int inputLen) // length of input block
    {
        unsigned int i, index, partLen;

        // Compute number of bytes mod 64
        index = (unsigned int)((context.count[0] >> 3) & 0x3F);

        // Update number of bits
        if ((context.count[0] += ((UINT4)inputLen << 3))
            < ((UINT4)inputLen << 3))
            context.count[1]++;
        context.count[1] += ((UINT4)inputLen >> 29);

        partLen = 64 - index;

        // Transform as many times as possible.
        if (inputLen >= partLen) {
            memcpy((POINTER)&context.buffer[index], (POINTER)input, partLen);
            MD5Transform(context.state, context.buffer);

            for (i = partLen; i + 63 < inputLen; i += 64)
                MD5Transform(context.state, &input[i]);

            index = 0;
        }
        else
            i = 0;

        /* Buffer remaining input */
        memcpy((POINTER)&context.buffer[index], (POINTER)&input[i], inputLen - i);
    }

    // MD5 finalization. Ends an MD5 message-digest operation, writing the
    // the message digest and zeroizing the context.
    // Writes to digestRaw
    void Final()
    {
        unsigned char bits[8];
        unsigned int index, padLen;

        // Save number of bits
        Encode(bits, context.count, 8);

        // Pad out to 56 mod 64.
        index = (unsigned int)((context.count[0] >> 3) & 0x3f);
        padLen = (index < 56) ? (56 - index) : (120 - index);
        Update(PADDING, padLen);

        // Append length (before padding)
        Update(bits, 8);

        // Store state in digest
        Encode(digestRaw, context.state, 16);

        // Zeroize sensitive information.
        memset((POINTER)&context, 0, sizeof(context));

        writeToString();
    }

    /// Buffer must be 32+1 (nul) = 33 chars long at least 
    void writeToString()
    {
        int pos;

        for (pos = 0; pos < 16; pos++)
            sprintf(digestChars + (pos * 2), "%02x", digestRaw[pos]);
    }


public:
    // an MD5 digest is a 16-byte number (32 hex digits)
    BYTE digestRaw[16];

    // This version of the digest is actually
    // a "printf'd" version of the digest.
    char digestChars[33];

    /// Load a file from disk and digest it
    // Digests a file and returns the result.
    char* digestFile(char *filename)
    {
        Init();

        FILE *file;

        int len;
        unsigned char buffer[1024];

        if ((file = fopen(filename, "rb")) == NULL)
            printf("%s can't be opened\n", filename);
        else
        {
            while (len = fread(buffer, 1, 1024, file))
                Update(buffer, len);
            Final();

            fclose(file);
        }

        return digestChars;
    }

    /// Digests a byte-array already in memory
    char* digestMemory(BYTE *memchunk, int len)
    {
        Init();
        Update(memchunk, len);
        Final();

        return digestChars;
    }

    // Digests a string and prints the result.
    char* digestString(char *string)
    {
        Init();
        Update((unsigned char*)string, strlen(string));
        Final();

        return digestChars;
    }
};

#endif

- Sanya Tayal

---

我尚未测试此方法是否有效，但我最喜欢这种方法，因为它甚至消除了对WinApi的依赖。这减少了在移植到其他架构时出现的可移植性问题。 - grenix

Answer 4

我看到了这个链接

但是为了在我的设备上运行这个函数，我做了一些更改，希望能够帮到你。

char* HashMD5(char* data, DWORD *result)
{
    DWORD dwStatus = 0;
    DWORD cbHash = 16;
    int i = 0;
    HCRYPTPROV cryptProv;
    HCRYPTHASH cryptHash;
    BYTE hash[16];
    char *hex = "0123456789abcdef";
    char *strHash;
    strHash = (char*)malloc(500);
    memset(strHash, '\0', 500);
    if (!CryptAcquireContext(&cryptProv, NULL, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
    {
        dwStatus = GetLastError();
        printf("CryptAcquireContext failed: %d\n", dwStatus);
        *result = dwStatus;
        return NULL;
    }
    if (!CryptCreateHash(cryptProv, CALG_MD5, 0, 0, &cryptHash))
    {
        dwStatus = GetLastError();
        printf("CryptCreateHash failed: %d\n", dwStatus);
        CryptReleaseContext(cryptProv, 0);
        *result = dwStatus;
        return NULL;
    }
    if (!CryptHashData(cryptHash, (BYTE*)data, strlen(data), 0))
    {
        dwStatus = GetLastError();
        printf("CryptHashData failed: %d\n", dwStatus);
        CryptReleaseContext(cryptProv, 0);
        CryptDestroyHash(cryptHash);
        *result = dwStatus;
        return NULL;
    }
    if (!CryptGetHashParam(cryptHash, HP_HASHVAL, hash, &cbHash, 0))
    {
        dwStatus = GetLastError();
        printf("CryptGetHashParam failed: %d\n", dwStatus);
        CryptReleaseContext(cryptProv, 0);
        CryptDestroyHash(cryptHash);
        *result = dwStatus;
        return NULL;
    }
    for (i = 0; i < cbHash; i++)
    {
        strHash[i * 2] = hex[hash[i] >> 4];
        strHash[(i * 2) + 1] = hex[hash[i] & 0xF];
    }
    CryptDestroyHash(cryptHash);
    CryptReleaseContext(cryptProv, 0);
    return strHash;
}

- Rudra