Java与CSP数据兼容之一：Java兼容CSP导出的RSA公钥数据

      Java中导入公钥数据,最直接的方式是导入X509证书数据，从中获取公钥对象。但是有时为了和客户端C++程序、特别是Windows平台数据兼容，需要把Windows下通过CryptoAPI导出的公钥数据转化为Java里的公钥对象，这样就需要做一定的转化。

      下面将讲述Java中这三种生成RSA公钥对象的方法：

一、通过X509证书创建

如果已知公钥所在的证书文件(X509格式)，那么可以直接通过证书获取对应的公钥对象。其相关代码如下：

/** * Created by Singler on 2015/10/12. * RSA加解密实现类 * */public class RSA {    /** 算法 */    private static String ALGORITHM = "RSA";    /** RSA bits */    private static int KEYSIZE = 1024;/** 由X509格式的证书内容创建公钥对象，证书内容用Base64编码 **/    public static RSAPublicKey CreatePublicKeyFromCert(String base64X509Cert) throws Exception {        /**将证书内容解码成二进制**/        Base64.Decoder decoder = Base64.getDecoder();        byte[] certData = decoder.decode(base64X509Cert);        /**构造证书对象**/        CertificateFactory certificatefactory = CertificateFactory.getInstance("X.509");        ByteArrayInputStream bain = new ByteArrayInputStream(certData);        X509Certificate Cert = (X509Certificate)certificatefactory.generateCertificate(bain);        /**获取公钥对象**/        RSAPublicKey pukKey = (RSAPublicKey)Cert.getPublicKey();        return pukKey;    }}public class Main {    static final String base64X509EncCert = "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";    public static void main(String[] args) {        try {            PublicKey pubKey = RSA.CreatePublicKeyFromCert(base64X509EncCert);            byte[] pubKeyData = pubKey.getEncoded();            String pubKeyStr = Convert.bytesToHexString(pubKeyData);            System.out.println(pubKeyStr);        }        catch (Exception e) {            System.out.println(e.getMessage());        }}}

该RSA公钥的X509 Encoded数据以16进制输出结果如下：

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

二、通过X509 Encoded数据创建

如果知道RSA公钥的X509 Encoded数据（比如上例中的输出），那可以直接由该数据创建公钥对象。主要代码如下：

/** * Created by Singler on 2015/10/12. * RSA加解密实现类 * */public class RSA {    /** 算法 */    private static String ALGORITHM = "RSA";    /** RSA bits */    private static int KEYSIZE = 1024;    /** 由X509 Encoded公钥数据构造公钥对象，公钥数据用Base64编码 */    public static RSAPublicKey CreatePublicKeyFromString(String base64EncodedPubKey) throws Exception {        /**将证书内容解码成二进制**/        Base64.Decoder decoder = Base64.getDecoder();        byte[] encodedPubkeyData = decoder.decode(base64EncodedPubKey);        /**构造公钥对象**/        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(encodedPubkeyData);        KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);        return (RSAPublicKey)keyFactory.generatePublic(x509EncodedKeySpec);    }}public class Main {    static String base64X509PubKey = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAw+D4pTERUemPtGIsterieWoTbRTNHgZ0DN9Z4qfrS03eWP339/JBkGyKwlBykCzYDt8L0YMW/1Xg1appYGvfo4mnVvxzIbc1tuanH1Z+wnXbrHqgW5ndlMjZ328mDyDIRHPmzA8FMYSvPGJtnrv4H9Tc+CeKrmiWskbzxBg4T/MUxYsk/+WWg6y5dUU61rwr19HyBZKq93xH8IOctgeRxsf6oItQJ1y1Nd55XVEul2Lh5KtTZzZMWAwreIq/EhZJH0XdbOeHhy78/fMmQtkKpJqLpRMTas1ZBWmVnqHxgBQcvheOu6cNGJYbadisJDk7Yo6MW3M7kRbybeU7C9yf7QIDAQAB"; public static void main(String[] args) {        try {            PublicKey pubKey = RSA.CreatePublicKeyFromString(base64X509PubKey);            byte[] pubKeyData = pubKey.getEncoded();            String pubKeyStr = Convert.bytesToHexString(pubKeyData);            System.out.println(pubKeyStr);        }        catch (Exception e) {            System.out.println(e.getMessage());        }    }}

三、通过Windows CryptoAPI导出的RSA公钥数据创建

有时RSA公钥数据来源于Windows客户端，Windows下常用的RSA函数来源于微软的CryptoAPI，其导出的RSA公钥数据为PUBLICKEYBLOB类型的数据块，数据块包含结构体BLOBHEADER和RSAPUBKEY。此时如果想把该RSA公钥应用于Java，就需要通过最原始的模和指数数据创建RSA公钥对象了。同时要注意，由于CrytoAPI的数据是大端模式，而Java里是小端模式，所以从CryptoAPI得到的模和指数都要经过转化才能在Java中使用。

具体过程如下：

1、使用CryptoAPI导出RSA公钥数据

2、得到公钥模和指数

3、大端到小端的转化

4、在Java中构造公钥对象

下面是C++调用CryptoAPI导出公钥数据的代码。

#include "stdafx.h"#include <windows.h>#include <atlconv.h>DWORD ExportPubKey(HCRYPTPROV hProv, DWORD dwKeyUsage, LPBYTE lpbtPubKey, LPDWORD lpdwLen);void Reverse(LPBYTE lpData, DWORD dwLen);void PrintDataInHex(LPBYTE lpData, DWORD dwLen);int _tmain(int argc, _TCHAR* argv[]){DWORD dwErr = 0;DWORD dwFlag = CRYPT_FIRST;DWORD dwParamLen = 2048;BYTE btParamData[2048] = {0};HCRYPTPROV hDefaultProv = NULL;HCRYPTPROV hProv = NULL;TCHAR *pContainer = NULL;const TCHAR tcCSPName[] = {_T("ZJCA CSP v1.0 for EnterSafe ePass3000gm")};//DWORD dwPubKeyLen = 0;DWORD dwModulusLen = 0;LPBYTE lpbtPubKey = NULL;LPBYTE lpbtModulus = NULL;BYTE btPubexp[4] = {0};BLOBHEADER *pBlobHeader = NULL;RSAPUBKEY *pRSAPubKey = NULL;USES_CONVERSION;if (!CryptAcquireContext(&hDefaultProv, NULL, tcCSPName, PROV_RSA_FULL, 0)){DWORD dwErr = GetLastError();printf("函数CryptAcquireContext失败! dwError = 0x%x\n", dwErr);goto END;}//获取CSP所有的容器名称，找到加密密钥所在容器while (CryptGetProvParam(hDefaultProv, PP_ENUMCONTAINERS, btParamData, &dwParamLen, dwFlag)){dwFlag = CRYPT_NEXT;#ifdef UNICODEpContainer = A2W((char*)btParamData);#elsepContainer = btParamData;#endifif (CryptAcquireContext(&hProv, pContainer, tcCSPName, PROV_RSA_FULL, 0)){HCRYPTKEY hKeyPair = NULL;if (CryptGetUserKey(hProv, AT_KEYEXCHANGE, &hKeyPair) && hKeyPair){CryptDestroyKey(hKeyPair);break;}}}if (!hProv){printf("Not found keyset!\n");goto END;}// 获取公钥数据长度dwErr = ExportPubKey(hProv, AT_KEYEXCHANGE, NULL, &dwPubKeyLen);if (0 != dwErr){printf("ExportPubKey() failed! dwErr = 0x%x\n", dwErr);goto END;}// 获取公钥数据lpbtPubKey = new BYTE[dwPubKeyLen];dwErr = ExportPubKey(hProv, AT_KEYEXCHANGE, lpbtPubKey, &dwPubKeyLen);if (0 != dwErr){printf("ExportPubKey() failed! dwErr = 0x%x\n", dwErr);goto END;}// 输出公钥数据printf("\nRSA public key:\n");PrintDataInHex(lpbtPubKey, dwPubKeyLen);// 获取公钥模数据，并换成小端模式pBlobHeader = (BLOBHEADER*)lpbtPubKey;pRSAPubKey = (RSAPUBKEY*)(lpbtPubKey + sizeof(BLOBHEADER));dwModulusLen = pRSAPubKey->bitlen / 8;lpbtModulus = new BYTE[dwModulusLen];memcpy(lpbtModulus, lpbtPubKey + sizeof(BLOBHEADER) + sizeof(RSAPUBKEY), dwModulusLen);Reverse(lpbtModulus, dwModulusLen);printf("\nRSA public key modulus:\n");PrintDataInHex(lpbtModulus, dwModulusLen);// 获取公钥指数数据memcpy(btPubexp, &pRSAPubKey->pubexp, 4);printf("\nRSA public key exp:\n");PrintDataInHex(btPubexp, 4);END:if (lpbtModulus){delete []lpbtModulus;lpbtModulus = NULL;}if (lpbtPubKey){delete []lpbtPubKey;lpbtPubKey = NULL;}if (hDefaultProv){CryptReleaseContext(hDefaultProv, 0);hDefaultProv = NULL;}if (hProv){CryptReleaseContext(hProv, 0);hProv = NULL;}getchar();return 0;}DWORD ExportPubKey(HCRYPTPROV hProv, DWORD dwKeyUsage, LPBYTE lpbtPubKey, LPDWORD lpdwLen){DWORD dwError = 0;DWORD dwDataLen = 0;HCRYPTKEY hKeyPair = NULL;if (!hProv || !lpdwLen){return 1;}//获取密钥对句柄if (!CryptGetUserKey(hProv, dwKeyUsage, &hKeyPair) || !hKeyPair){dwError = GetLastError();return dwError;}//导出密钥对中的公钥数据长度if (!CryptExportKey(hKeyPair, 0, PUBLICKEYBLOB, 0, NULL, &dwDataLen)){dwError = GetLastError();goto FREE_MEMORY;}//返回数据长度if (!lpbtPubKey){dwError = 0;*lpdwLen = dwDataLen;goto FREE_MEMORY;}//导出密钥对中的公钥数据if (!CryptExportKey(hKeyPair, 0, PUBLICKEYBLOB, 0, lpbtPubKey, &dwDataLen)){dwError = GetLastError();goto FREE_MEMORY;}*lpdwLen = dwDataLen;FREE_MEMORY:if (hKeyPair){CryptDestroyKey(hKeyPair);hKeyPair = NULL;}return dwError;}void Reverse(LPBYTE lpData, DWORD dwLen){BYTE temp = 0;for (ULONG i = 0; i < dwLen / 2; i++){temp = lpData[i];lpData[i] = lpData[dwLen - (i + 1)];lpData[dwLen - ( i + 1)] = temp;}}void PrintDataInHex(LPBYTE lpData, DWORD dwLen){for (DWORD dwIndex = 0; dwIndex < dwLen; dwIndex++){printf("%02X ", lpData[dwIndex]);if ((dwIndex + 1) % 16 == 0){printf("\n");}}}

程序输入结果如下：

下一步，需要把C++得到的模和指数数据，按16进制的字符串形式组织好，然后构造成RSA公钥对象。具体代码如下：

/** * Created by Singler on 2015/10/12. * RSA加解密实现类 * */public class RSA {    /** 算法 */    private static String ALGORITHM = "RSA";    /** RSA bits */    private static int KEYSIZE = 1024;    /** 由模和指数构造公钥对象，模和指数由16进制字符串表示 */    public static RSAPublicKey CreatePublicKeyFromModulus(String modulusIn16Radix, String exponentIn16Radix) throws Exception {        BigInteger m = new BigInteger(modulusIn16Radix, 16);        BigInteger e = new BigInteger(exponentIn16Radix, 16);        KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);        RSAPublicKeySpec keySpec = new RSAPublicKeySpec(m, e);        RSAPublicKey  rsaPubKey = (RSAPublicKey)keyFactory.generatePublic(keySpec);        return rsaPubKey;    }}public class Main {    static final String pubKeyModulusInHex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static final String pubKeyExpInHex = "01000100";    public static void main(String[] args) {        try {            PublicKey pubKey = RSA.CreatePublicKeyFromModulus(pubKeyModulusInHex, pubKeyExpInHex);            byte[] pubKeyData = pubKey.getEncoded();            String pubKeyStr = Base64.getEncoder().encodeToString(pubKeyData); //Convert.bytesToHexString(pubKeyData);            System.out.println(pubKeyStr);        }        catch (Exception e) {            System.out.println(e.getMessage());        }}}

该段Java代码输入的X509 Encoded公钥数据如下：

MIIBIzANBgkqhkiG9w0BAQEFAAOCARAAMIIBCwKCAQEAw+D4pTERUemPtGIsterieWoTbRTNHgZ0DN9Z4qfrS03eWP339/JBkGyKwlBykCzYDt8L0YMW/1Xg1appYGvfo4mnVvxzIbc1tuanH1Z+wnXbrHqgW5ndlMjZ328mDyDIRHPmzA8FMYSvPGJtnrv4H9Tc+CeKrmiWskbzxBg4T/MUxYsk/+WWg6y5dUU61rwr19HyBZKq93xH8IOctgeRxsf6oItQJ1y1Nd55XVEul2Lh5KtTZzZMWAwreIq/EhZJH0XdbOeHhy78/fMmQtkKpJqLpRMTas1ZBWmVnqHxgBQcvheOu6cNGJYbadisJDk7Yo6MW3M7kRbybeU7C9yf7QIEAQABAA==