我目前正在开发一个用C++编写的项目,该项目利用CryptoAPI执行Diffie-Hellman密钥交换.我在使用这个工作时遇到了一些麻烦,因为我得到的最终RC4会话密钥不能用于加密Python中的相同文本(使用pycrypto).
执行Diffie-Hellman密钥交换的C++代码取自msdn,但此处包含后代:
#include#include #include #pragma comment(lib, "crypt32.lib") // The key size, in bits. #define DHKEYSIZE 512 // Prime in little-endian format. static const BYTE g_rgbPrime[] = { 0x91, 0x02, 0xc8, 0x31, 0xee, 0x36, 0x07, 0xec, 0xc2, 0x24, 0x37, 0xf8, 0xfb, 0x3d, 0x69, 0x49, 0xac, 0x7a, 0xab, 0x32, 0xac, 0xad, 0xe9, 0xc2, 0xaf, 0x0e, 0x21, 0xb7, 0xc5, 0x2f, 0x76, 0xd0, 0xe5, 0x82, 0x78, 0x0d, 0x4f, 0x32, 0xb8, 0xcb, 0xf7, 0x0c, 0x8d, 0xfb, 0x3a, 0xd8, 0xc0, 0xea, 0xcb, 0x69, 0x68, 0xb0, 0x9b, 0x75, 0x25, 0x3d, 0xaa, 0x76, 0x22, 0x49, 0x94, 0xa4, 0xf2, 0x8d }; // Generator in little-endian format. static BYTE g_rgbGenerator[] = { 0x02, 0x88, 0xd7, 0xe6, 0x53, 0xaf, 0x72, 0xc5, 0x8c, 0x08, 0x4b, 0x46, 0x6f, 0x9f, 0x2e, 0xc4, 0x9c, 0x5c, 0x92, 0x21, 0x95, 0xb7, 0xe5, 0x58, 0xbf, 0xba, 0x24, 0xfa, 0xe5, 0x9d, 0xcb, 0x71, 0x2e, 0x2c, 0xce, 0x99, 0xf3, 0x10, 0xff, 0x3b, 0xcb, 0xef, 0x6c, 0x95, 0x22, 0x55, 0x9d, 0x29, 0x00, 0xb5, 0x4c, 0x5b, 0xa5, 0x63, 0x31, 0x41, 0x13, 0x0a, 0xea, 0x39, 0x78, 0x02, 0x6d, 0x62 }; BYTE g_rgbData[] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08}; int _tmain(int argc, _TCHAR* argv[]) { UNREFERENCED_PARAMETER(argc); UNREFERENCED_PARAMETER(argv); BOOL fReturn; HCRYPTPROV hProvParty1 = NULL; HCRYPTPROV hProvParty2 = NULL; DATA_BLOB P; DATA_BLOB G; HCRYPTKEY hPrivateKey1 = NULL; HCRYPTKEY hPrivateKey2 = NULL; PBYTE pbKeyBlob1 = NULL; PBYTE pbKeyBlob2 = NULL; HCRYPTKEY hSessionKey1 = NULL; HCRYPTKEY hSessionKey2 = NULL; PBYTE pbData = NULL; /************************ Construct data BLOBs for the prime and generator. The P and G values, represented by the g_rgbPrime and g_rgbGenerator arrays respectively, are shared values that have been agreed to by both parties. ************************/ P.cbData = DHKEYSIZE/8; P.pbData = (BYTE*)(g_rgbPrime); G.cbData = DHKEYSIZE/8; G.pbData = (BYTE*)(g_rgbGenerator); /************************ Create the private Diffie-Hellman key for party 1. ************************/ // Acquire a provider handle for party 1. fReturn = CryptAcquireContext( &hProvParty1, NULL, MS_ENH_DSS_DH_PROV, PROV_DSS_DH, CRYPT_VERIFYCONTEXT); if(!fReturn) { goto ErrorExit; } // Create an ephemeral private key for party 1. fReturn = CryptGenKey( hProvParty1, CALG_DH_EPHEM, DHKEYSIZE << 16 | CRYPT_EXPORTABLE | CRYPT_PREGEN, &hPrivateKey1); if(!fReturn) { goto ErrorExit; } // Set the prime for party 1's private key. fReturn = CryptSetKeyParam( hPrivateKey1, KP_P, (PBYTE)&P, 0); if(!fReturn) { goto ErrorExit; } // Set the generator for party 1's private key. fReturn = CryptSetKeyParam( hPrivateKey1, KP_G, (PBYTE)&G, 0); if(!fReturn) { goto ErrorExit; } // Generate the secret values for party 1's private key. fReturn = CryptSetKeyParam( hPrivateKey1, KP_X, NULL, 0); if(!fReturn) { goto ErrorExit; } /************************ Create the private Diffie-Hellman key for party 2. ************************/ // Acquire a provider handle for party 2. fReturn = CryptAcquireContext( &hProvParty2, NULL, MS_ENH_DSS_DH_PROV, PROV_DSS_DH, CRYPT_VERIFYCONTEXT); if(!fReturn) { goto ErrorExit; } // Create an ephemeral private key for party 2. fReturn = CryptGenKey( hProvParty2, CALG_DH_EPHEM, DHKEYSIZE << 16 | CRYPT_EXPORTABLE | CRYPT_PREGEN, &hPrivateKey2); if(!fReturn) { goto ErrorExit; } // Set the prime for party 2's private key. fReturn = CryptSetKeyParam( hPrivateKey2, KP_P, (PBYTE)&P, 0); if(!fReturn) { goto ErrorExit; } // Set the generator for party 2's private key. fReturn = CryptSetKeyParam( hPrivateKey2, KP_G, (PBYTE)&G, 0); if(!fReturn) { goto ErrorExit; } // Generate the secret values for party 2's private key. fReturn = CryptSetKeyParam( hPrivateKey2, KP_X, NULL, 0); if(!fReturn) { goto ErrorExit; } /************************ Export Party 1's public key. ************************/ // Public key value, (G^X) mod P is calculated. DWORD dwDataLen1; // Get the size for the key BLOB. fReturn = CryptExportKey( hPrivateKey1, NULL, PUBLICKEYBLOB, 0, NULL, &dwDataLen1); if(!fReturn) { goto ErrorExit; } // Allocate the memory for the key BLOB. if(!(pbKeyBlob1 = (PBYTE)malloc(dwDataLen1))) { goto ErrorExit; } // Get the key BLOB. fReturn = CryptExportKey( hPrivateKey1, 0, PUBLICKEYBLOB, 0, pbKeyBlob1, &dwDataLen1); if(!fReturn) { goto ErrorExit; } /************************ Export Party 2's public key. ************************/ // Public key value, (G^X) mod P is calculated. DWORD dwDataLen2; // Get the size for the key BLOB. fReturn = CryptExportKey( hPrivateKey2, NULL, PUBLICKEYBLOB, 0, NULL, &dwDataLen2); if(!fReturn) { goto ErrorExit; } // Allocate the memory for the key BLOB. if(!(pbKeyBlob2 = (PBYTE)malloc(dwDataLen2))) { goto ErrorExit; } // Get the key BLOB. fReturn = CryptExportKey( hPrivateKey2, 0, PUBLICKEYBLOB, 0, pbKeyBlob2, &dwDataLen2); if(!fReturn) { goto ErrorExit; } /************************ Party 1 imports party 2's public key. The imported key will contain the new shared secret key (Y^X) mod P. ************************/ fReturn = CryptImportKey( hProvParty1, pbKeyBlob2, dwDataLen2, hPrivateKey1, 0, &hSessionKey2); if(!fReturn) { goto ErrorExit; } /************************ Party 2 imports party 1's public key. The imported key will contain the new shared secret key (Y^X) mod P. ************************/ fReturn = CryptImportKey( hProvParty2, pbKeyBlob1, dwDataLen1, hPrivateKey2, 0, &hSessionKey1); if(!fReturn) { goto ErrorExit; } /************************ Convert the agreed keys to symmetric keys. They are currently of the form CALG_AGREEDKEY_ANY. Convert them to CALG_RC4. ************************/ ALG_ID Algid = CALG_RC4; // Enable the party 1 public session key for use by setting the // ALGID. fReturn = CryptSetKeyParam( hSessionKey1, KP_ALGID, (PBYTE)&Algid, 0); if(!fReturn) { goto ErrorExit; } // Enable the party 2 public session key for use by setting the // ALGID. fReturn = CryptSetKeyParam( hSessionKey2, KP_ALGID, (PBYTE)&Algid, 0); if(!fReturn) { goto ErrorExit; } /************************ Encrypt some data with party 1's session key. ************************/ // Get the size. DWORD dwLength = sizeof(g_rgbData); fReturn = CryptEncrypt( hSessionKey1, 0, TRUE, 0, NULL, &dwLength, sizeof(g_rgbData)); if(!fReturn) { goto ErrorExit; } // Allocate a buffer to hold the encrypted data. pbData = (PBYTE)malloc(dwLength); if(!pbData) { goto ErrorExit; } // Copy the unencrypted data to the buffer. The data will be // encrypted in place. memcpy(pbData, g_rgbData, sizeof(g_rgbData)); // Encrypt the data. dwLength = sizeof(g_rgbData); fReturn = CryptEncrypt( hSessionKey1, 0, TRUE, 0, pbData, &dwLength, sizeof(g_rgbData)); if(!fReturn) { goto ErrorExit; } /************************ Decrypt the data with party 2's session key. ************************/ dwLength = sizeof(g_rgbData); fReturn = CryptDecrypt( hSessionKey2, 0, TRUE, 0, pbData, &dwLength); if(!fReturn) { goto ErrorExit; } ErrorExit: if(pbData) { free(pbData); pbData = NULL; } if(hSessionKey2) { CryptDestroyKey(hSessionKey2); hSessionKey2 = NULL; } if(hSessionKey1) { CryptDestroyKey(hSessionKey1); hSessionKey1 = NULL; } if(pbKeyBlob2) { free(pbKeyBlob2); pbKeyBlob2 = NULL; } if(pbKeyBlob1) { free(pbKeyBlob1); pbKeyBlob1 = NULL; } if(hPrivateKey2) { CryptDestroyKey(hPrivateKey2); hPrivateKey2 = NULL; } if(hPrivateKey1) { CryptDestroyKey(hPrivateKey1); hPrivateKey1 = NULL; } if(hProvParty2) { CryptReleaseContext(hProvParty2, 0); hProvParty2 = NULL; } if(hProvParty1) { CryptReleaseContext(hProvParty1, 0); hProvParty1 = NULL; } return 0; }
我相信我可以在Python中完成Diffie-Hellman密钥交换,因为我可以无错误地生成相同的公钥和私钥.我在这个存储库上建立了我的Diffie-Hellman密钥交换.
我无法测试这个,但是因为我似乎无法获得从C++代码导出的共享秘密(类似于这个线程,从未得到满意的回答).但是,我可以使用以下代码获取RC4会话密钥:
// Get the key length DWORD keylen; CryptExportKey( hSessionKey1, NULL, PLAINTEXTKEYBLOB, 0, NULL, &keylen); // Get the session key CryptExportKey( hSessionKey1, NULL, PLAINTEXTKEYBLOB, 0, encKey, &keylen);
这个函数的输出让我:
08 02 00 00 01 68 00 00 10 00 00 00 75 2c 59 8c 6e e0 8c 9f ed 30 17 7e 9d a5 85 2b
我知道这有一个12字节的头+长度,所以我留下了以下16字节的RC4会话密钥:
75 2c 59 8c 6e e0 8c 9f ed 30 17 7e 9d a5 85 2b
所以我目前正在尝试验证我可以使用我从中获取的RC4加密相同的明文CryptExportKey
.我目前正在尝试g_rgbData
从上面的C++代码加密,该代码设置为:
BYTE g_rgbData[] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
使用C++代码,我得到以下加密输出:
cc 94 aa ec 86 6e a8 26
使用pycrypto我有以下代码:
from Crypto.Cipher import ARC4 key = '75 2c 59 8c 6e e0 8c 9f ed 30 17 7e 9d a5 85 2b' key = key.replace(' ', '').decode('hex') plaintext = '0102030405060708' plaintext = plaintext.replace(' ', '').decode('hex') rc4 = ARC4.new(key) encrypted = rc4.encrypt(plaintext) print encrypted.encode('hex')
这导致以下输出:
00 5b 64 25 4e a5 62 e3
哪个与C++输出不匹配.我玩过endianess,但我怀疑还有其他事情可能发生.
对不起,如果这是漫长的啰嗦,但它带给我两个问题:
每当你从共享密钥转换到RC4(使用CryptSetKeyParam
with CALG_RC4
)时,这里真正发生了什么?我似乎无法在任何地方找到有关此过程的任何信息,以便我可以在Python中实现它.
知道为什么我的RC4不能在Python中使用相同的密钥和相同的明文吗?
任何帮助将不胜感激!
终于有时间查看你的代码了.当我在本地运行您的代码时,我能够导出会话密钥并可以在pycrypto中成功使用它.我的猜测是你要么没有正确导出会话密钥(例如你发布的是你正在运行的内容?),要么你在C++中加密的数据与你在Python中加密的数据不同 - 仔细检查数据你加密也是正确的.我怀疑它可能是后者,因为没有太多可以搞砸CryptExportKey
你发布的内容.