使用crypto api的加密解密源代码

#include "stdafx.h"
#include < stdio.h >
#include < windows.h >
#include < wincrypt.h >
#define MY_ENCODING_TYPE  (PKCS_7_ASN_ENCODING | X509_ASN_ENCODING)
#define KEYLENGTH  0x00800000
void HandleError(char *s);

//--------------------------------------------------------------------
//  These additional #define statements are required.
#define ENCRYPT_ALGORITHM CALG_RC4
#define ENCRYPT_BLOCK_SIZE 8

//   Declare the function EncryptFile. The function definition
//   follows main.

BOOL EncryptFile(
PCHAR szSource,
PCHAR szDestination,
PCHAR szPassword);
BOOL DecryptFile(
PCHAR szSource,
PCHAR szDestination,
PCHAR szPassword);

//--------------------------------------------------------------------
//   Begin main.

void main(void)
{
CHAR szSource[100];
CHAR szDestination[100];
CHAR szPassword[100];
int way[1];
printf("please choose encryption of 1 or decryption of 2\n\n");
scanf("%d",way);

if (way[0] == 1)
{
printf("Encrypt a file. \n\n");
printf("Enter the name of the file to be encrypted: ");
scanf("%s",szSource);
printf("Enter the name of the output file: ");
scanf("%s",szDestination);
printf("Enter the password:");
scanf("%s",szPassword);
if(EncryptFile(szSource, szDestination, szPassword))
{
printf("Encryption of the file %s was a success. \n", szSource);
printf("The encrypted data is in file %s.\n",szDestination);
}
else
{
HandleError("Error encrypting file!");
}
}else{
printf("Decrypt a file. \n\n");
printf("Enter the name of the file to be decrypted: ");
scanf("%s",szSource);
printf("Enter the name of the output file: ");
scanf("%s",szDestination);
printf("Enter the password:");
scanf("%s",szPassword);
if(DecryptFile(szSource, szDestination, szPassword))
{
printf("Decryption of the file %s was a success. \n", szSource);
printf("The decrypted data is in file %s.\n",szDestination);
}
else
{
HandleError("Error decrypting file!");
}
}

} // End of main

//--------------------------------------------------------------------
//   Code for the function EncryptFile called by main.

static BOOL EncryptFile(
PCHAR szSource,
PCHAR szDestination,
PCHAR szPassword)
//--------------------------------------------------------------------
//   Parameters passed are:
//     szSource, the name of the input, a plaintext file.
//     szDestination, the name of the output, an encrypted file to be
//         created.
//     szPassword, the password.
{
//--------------------------------------------------------------------
//   Declare and initialize local variables.

FILE *hSource;
FILE *hDestination;

HCRYPTPROV hCryptProv;
HCRYPTKEY hKey;
HCRYPTHASH hHash;

PBYTE pbBuffer;
DWORD dwBlockLen;
DWORD dwBufferLen;
DWORD dwCount;

//--------------------------------------------------------------------
// Open source file.
if(hSource = fopen(szSource,"rb"))
{
printf("The source plaintext file, %s, is open. \n", szSource);
}
else
{
HandleError("Error opening source plaintext file!");
}

//--------------------------------------------------------------------
// Open destination file.
if(hDestination = fopen(szDestination,"wb"))
{
printf("Destination file %s is open. \n", szDestination);
}
else
{
HandleError("Error opening destination ciphertext file!");
}

//以下获得一个CSP句柄
if(CryptAcquireContext(
&hCryptProv,
NULL,				//NULL表示使用默认密钥容器，默认密钥容器名
//为用户登陆名
NULL,
PROV_RSA_FULL,
0))
{
printf("A cryptographic provider has been acquired. \n");
}
else
{
if(CryptAcquireContext(
&hCryptProv,
NULL,
NULL,
PROV_RSA_FULL,
CRYPT_NEWKEYSET))//创建密钥容器
{
//创建密钥容器成功，并得到CSP句柄
printf("A new key container has been created.\n");
}
else
{
HandleError("Could not create a new key container.\n");
}

}

//--------------------------------------------------------------------
// 创建一个会话密钥（session key）
// 会话密钥也叫对称密钥，用于对称加密算法。
// （注: 一个Session是指从调用函数CryptAcquireContext到调用函数
//   CryptReleaseContext 期间的阶段。会话密钥只能存在于一个会话过程）

//--------------------------------------------------------------------
// Create a hash object.
if(CryptCreateHash(
hCryptProv,
CALG_MD5,
0,
0,
&hHash))
{
printf("A hash object has been created. \n");
}
else
{
HandleError("Error during CryptCreateHash!\n");
}

//--------------------------------------------------------------------
// 用输入的密码产生一个散列
if(CryptHashData(
hHash,
(BYTE *)szPassword,
strlen(szPassword),
0))
{
printf("The password has been added to the hash. \n");
}
else
{
HandleError("Error during CryptHashData. \n");
}

//--------------------------------------------------------------------
// 通过散列生成会话密钥
if(CryptDeriveKey(
hCryptProv,
ENCRYPT_ALGORITHM,
hHash,
KEYLENGTH,
&hKey))
{
printf("An encryption key is derived from the password hash. \n");
}
else
{
HandleError("Error during CryptDeriveKey!\n");
}
//--------------------------------------------------------------------
// Destroy the hash object.

CryptDestroyHash(hHash);
hHash = NULL;

//--------------------------------------------------------------------
//  The session key is now ready.

//--------------------------------------------------------------------
// 因为加密算法是按ENCRYPT_BLOCK_SIZE 大小的块加密的，所以被加密的
// 数据长度必须是ENCRYPT_BLOCK_SIZE 的整数倍。下面计算一次加密的
// 数据长度。

dwBlockLen = 1000 - 1000 % ENCRYPT_BLOCK_SIZE;

//--------------------------------------------------------------------
// Determine the block size. If a block cipher is used,
// it must have room for an extra block.

if(ENCRYPT_BLOCK_SIZE > 1)
dwBufferLen = dwBlockLen + ENCRYPT_BLOCK_SIZE;
else
dwBufferLen = dwBlockLen;

//--------------------------------------------------------------------
// Allocate memory.
if(pbBuffer = (BYTE *)malloc(dwBufferLen))
{
printf("Memory has been allocated for the buffer. \n");
}
else
{
HandleError("Out of memory. \n");
}
//--------------------------------------------------------------------
// In a do loop, encrypt the source file and write to the source file.

do
{

//--------------------------------------------------------------------
// Read up to dwBlockLen bytes from the source file.
dwCount = fread(pbBuffer, 1, dwBlockLen, hSource);
if(ferror(hSource))
{
HandleError("Error reading plaintext!\n");
}

//--------------------------------------------------------------------
// 加密数据
if(!CryptEncrypt(
hKey,			//密钥
0,				//如果数据同时进行散列和加密，这里传入一个
//散列对象
feof(hSource),	//如果是最后一个被加密的块，输入TRUE.如果不是输.
//入FALSE这里通过判断是否到文件尾来决定是否为
//最后一块。
0,				//保留
pbBuffer,		//输入被加密数据，输出加密后的数据
&dwCount,		//输入被加密数据实际长度，输出加密后数据长度
dwBufferLen
))	//pbBuffer的大小。
{
HandleError("Error during CryptEncrypt. \n");
}

//--------------------------------------------------------------------
// Write data to the destination file.

fwrite(pbBuffer, 1, dwCount, hDestination);
if(ferror(hDestination))
{
HandleError("Error writing ciphertext.");
}

}
while(!feof(hSource));
//--------------------------------------------------------------------
//  End the do loop when the last block of the source file has been
//  read, encrypted, and written to the destination file.

//--------------------------------------------------------------------
// Close files.

if(hSource)
fclose(hSource);
if(hDestination)
fclose(hDestination);

//--------------------------------------------------------------------
// Free memory.

if(pbBuffer)
free(pbBuffer);

//--------------------------------------------------------------------
// Destroy session key.

if(hKey)
CryptDestroyKey(hKey);

//--------------------------------------------------------------------
// Destroy hash object.

if(hHash)
CryptDestroyHash(hHash);

//--------------------------------------------------------------------
// Release provider handle.

if(hCryptProv)
CryptReleaseContext(hCryptProv, 0);
return(TRUE);
} // End of Encryptfile

//--------------------------------------------------------------------
//  This example uses the function HandleError, a simple error
//  handling function, to print an error message to the standard error
//  (stderr) file and exit the program.
//  For most applications, replace this function with one
//  that does more extensive error reporting.

void HandleError(char *s)
{
fprintf(stderr,"An error occurred in running the program. \n");
fprintf(stderr,"%s\n",s);
fprintf(stderr, "Error number %x.\n", GetLastError());
fprintf(stderr, "Program terminating. \n");
exit(1);
} // End of HandleError

static BOOL DecryptFile(
PCHAR szSource,
PCHAR szDestination,
PCHAR szPassword)
//--------------------------------------------------------------------
//   Parameters passed are:
//     szSource, the name of the input, a plaintext file.
//     szDestination, the name of the output, an encrypted file to be
//         created.
//     szPassword, the password.
{
//--------------------------------------------------------------------
//   Declare and initialize local variables.

FILE *hSource;
FILE *hDestination;

HCRYPTPROV hCryptProv;
HCRYPTKEY hKey;
HCRYPTHASH hHash;

PBYTE pbBuffer;
DWORD dwBlockLen;
DWORD dwBufferLen;
DWORD dwCount;

//--------------------------------------------------------------------
// Open source file.
if(hSource = fopen(szSource,"rb"))
{
printf("The source plaintext file, %s, is open. \n", szSource);
}
else
{
HandleError("Error opening source plaintext file!");
}

//--------------------------------------------------------------------
// Open destination file.
if(hDestination = fopen(szDestination,"wb"))
{
printf("Destination file %s is open. \n", szDestination);
}
else
{
HandleError("Error opening destination ciphertext file!");
}

//以下获得一个CSP句柄
if(CryptAcquireContext(
&hCryptProv,
NULL,				//NULL表示使用默认密钥容器，默认密钥容器名
//为用户登陆名
NULL,
PROV_RSA_FULL,
0))
{
printf("A cryptographic provider has been acquired. \n");
}
else
{
if(CryptAcquireContext(
&hCryptProv,
NULL,
NULL,
PROV_RSA_FULL,
CRYPT_NEWKEYSET))//创建密钥容器
{
//创建密钥容器成功，并得到CSP句柄
printf("A new key container has been created.\n");
}
else
{
HandleError("Could not create a new key container.\n");
}

}

//--------------------------------------------------------------------
// 创建一个会话密钥（session key）
// 会话密钥也叫对称密钥，用于对称加密算法。
// （注: 一个Session是指从调用函数CryptAcquireContext到调用函数
//   CryptReleaseContext 期间的阶段。会话密钥只能存在于一个会话过程）

//--------------------------------------------------------------------
// Create a hash object.
if(CryptCreateHash(
hCryptProv,
CALG_MD5,
0,
0,
&hHash))
{
printf("A hash object has been created. \n");
}
else
{
HandleError("Error during CryptCreateHash!\n");
}

//--------------------------------------------------------------------
// 用输入的密码产生一个散列
if(CryptHashData(
hHash,
(BYTE *)szPassword,
strlen(szPassword),
0))
{
printf("The password has been added to the hash. \n");
}
else
{
HandleError("Error during CryptHashData. \n");
}

//--------------------------------------------------------------------
// 通过散列生成会话密钥
if(CryptDeriveKey(
hCryptProv,
ENCRYPT_ALGORITHM,
hHash,
KEYLENGTH,
&hKey))
{
printf("An encryption key is derived from the password hash. \n");
}
else
{
HandleError("Error during CryptDeriveKey!\n");
}
//--------------------------------------------------------------------
// Destroy the hash object.

CryptDestroyHash(hHash);
hHash = NULL;

//--------------------------------------------------------------------
//  The session key is now ready.

//--------------------------------------------------------------------
// 因为加密算法是按ENCRYPT_BLOCK_SIZE 大小的块加密的，所以被加密的
// 数据长度必须是ENCRYPT_BLOCK_SIZE 的整数倍。下面计算一次加密的
// 数据长度。

dwBlockLen = 1000 - 1000 % ENCRYPT_BLOCK_SIZE;

//--------------------------------------------------------------------
// Determine the block size. If a block cipher is used,
// it must have room for an extra block.

if(ENCRYPT_BLOCK_SIZE > 1)
dwBufferLen = dwBlockLen + ENCRYPT_BLOCK_SIZE;
else
dwBufferLen = dwBlockLen;

//--------------------------------------------------------------------
// Allocate memory.
if(pbBuffer = (BYTE *)malloc(dwBufferLen))
{
printf("Memory has been allocated for the buffer. \n");
}
else
{
HandleError("Out of memory. \n");
}
//--------------------------------------------------------------------
// In a do loop, encrypt the source file and write to the source file.

do
{

//--------------------------------------------------------------------
// Read up to dwBlockLen bytes from the source file.
dwCount = fread(pbBuffer, 1, dwBlockLen, hSource);
if(ferror(hSource))
{
HandleError("Error reading plaintext!\n");
}

//--------------------------------------------------------------------
// 加密数据
if(!CryptDecrypt(
hKey,			//密钥
0,				//如果数据同时进行散列和加密，这里传入一个
//散列对象
feof(hSource),	//如果是最后一个被加密的块，输入TRUE.如果不是输.
//入FALSE这里通过判断是否到文件尾来决定是否为
//最后一块。
0,				//保留
pbBuffer,		//输入被加密数据，输出加密后的数据
&dwCount		//输入被加密数据实际长度，输出加密后数据长度
//dwBufferLen
))	//pbBuffer的大小。
{
HandleError("Error during CryptEncrypt. \n");
}

//--------------------------------------------------------------------
// Write data to the destination file.

fwrite(pbBuffer, 1, dwCount, hDestination);
if(ferror(hDestination))
{
HandleError("Error writing ciphertext.");
}

}
while(!feof(hSource));
//--------------------------------------------------------------------
//  End the do loop when the last block of the source file has been
//  read, encrypted, and written to the destination file.

//--------------------------------------------------------------------
// Close files.

if(hSource)
fclose(hSource);
if(hDestination)
fclose(hDestination);

//--------------------------------------------------------------------
// Free memory.

if(pbBuffer)
free(pbBuffer);

//--------------------------------------------------------------------
// Destroy session key.

if(hKey)
CryptDestroyKey(hKey);

//--------------------------------------------------------------------
// Destroy hash object.

if(hHash)
CryptDestroyHash(hHash);

//--------------------------------------------------------------------
// Release provider handle.

if(hCryptProv)
CryptReleaseContext(hCryptProv, 0);
return(TRUE);
}