C++、C#、秘密鍵、公開鍵、RSA

RSAの鍵作成(C++)->暗号化(C#)->復号化(C++)の例

RSAの鍵作成(C++)

int _tmain(int argc, _TCHAR* argv[])

{

	// RSA 秘密鍵と公開鍵を作成し、両方をファイル化
	HCRYPTPROV hCryptprov; 

	BOOL bl = CryptAcquireContext(&hCryptprov, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, 0 );

	ATLASSERT( bl );
    HCRYPTKEY hKey;
	bl = CryptGenKey(hCryptprov, CALG_RSA_KEYX, KEYLENGTH<<16  | CRYPT_EXPORTABLE, &hKey);

	ATLASSERT( bl );
	DWORD	dwPrivateKeySize;

	bl = CryptExportKey( hKey, 0, PRIVATEKEYBLOB,0, NULL, &dwPrivateKeySize); // サイズ取得

	BYTE* privateKey = new BYTE[dwPrivateKeySize];

	bl = CryptExportKey( hKey, 0, PRIVATEKEYBLOB,0, privateKey, &dwPrivateKeySize); // 596

	ATLASSERT( bl );
	DWORD	dwPublicKeySize;

	bl = CryptExportKey( hKey, 0, PUBLICKEYBLOB,0, NULL, &dwPublicKeySize); // サイズ取得

	BYTE* publicKey = new BYTE[dwPublicKeySize];

	bl = CryptExportKey( hKey, 0, PUBLICKEYBLOB,0, publicKey, &dwPublicKeySize); // 148

	ATLASSERT( bl );
	FILE* pf = fopen( "privatekey.bin", "wb" );

	fwrite( privateKey, 1, dwPrivateKeySize, pf );

	fclose(pf);
	 pf = fopen( "publickey.bin", "wb" );

	fwrite( publicKey, 1, dwPublicKeySize, pf );

	fclose(pf);


	delete [] privateKey;

	delete [] publicKey;
	CryptDestroyKey( hKey );

	CryptReleaseContext(hCryptprov, 0);
	return 0;

}

暗号化(C#)

{			

	// RSA 1024bit

	var rsa = new System.Security.Cryptography.RSACryptoServiceProvider();
	// 公開鍵を受け取る

	BinaryReader sr = new BinaryReader( File.OpenRead("publickey.bin"));

	long len = sr.BaseStream.Length;

	Byte [] blob = new Byte[len];

	sr.Read( blob, 0, (int)len );

	sr.Close();

	

	 // 公開鍵をインポート

	rsa.ImportCspBlob( blob );
	// 公開鍵で暗号化

	byte[] data = rsa.Encrypt( Encoding.ASCII.GetBytes("password"), false ); // パスワードは英数字が普通なので、ASCIIエンコード
	// ファイル化

	BinaryWriter wr = new BinaryWriter( File.OpenWrite("encrypt.bin"));

	wr.Write( data, 0, data.Length );

	wr.Close();

}

復号化(C++)

BYTE* MyFileRead( LPCSTR fnm, DWORD* plen );

BYTE* ByteArraySwap( BYTE* buffer, int len );
int _tmain(int argc, _TCHAR* argv[])

{

	HCRYPTPROV hCryptprov; 

	HCRYPTKEY hkey;

	

	BOOL bl = CryptAcquireContext(&hCryptprov, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, 0 );

	ATLASSERT( bl );
	DWORD prlen,dlen;
	// 秘密鍵

	BYTE* privatekey = MyFileRead( "privatekey.bin" , &prlen);

	

	// 暗号化されたデータ

	BYTE* data = MyFileRead( "encrypt.bin", &dlen );

	

	// 復号化のため、秘密鍵をインポート

	bl = CryptImportKey( hCryptprov, privatekey, prlen, 0 ,0, &hkey );

	ATLASSERT( bl );
	BYTE* ctext = ByteArraySwap( data, dlen ); // to big endian
	// 復号化

	bl = ::CryptDecrypt( hkey, 0, TRUE,0, ctext, &dlen );

	ATLASSERT( bl );

	

	CStringA str((LPCSTR)ctext, dlen); // 元がEncoding.ASCII.GetBytesなのでそのままLPCSTRになる
	ATLASSERT( str == "password" );
	delete [] privatekey;

	delete [] ctext;
	CryptDestroyKey( hkey );

	CryptReleaseContext(hCryptprov, 0);
	return 0;

}
BYTE* MyFileRead( LPCSTR fnm, DWORD* plen )

{

	FILE* pf = ::fopen( fnm, "rb" );

	::fseek( pf, 0, SEEK_END );

	DWORD len = ::ftell(pf);

	::fseek( pf, 0, SEEK_SET );
	BYTE* buf = new BYTE[len];

	::fread( buf,1,len,pf);

	fclose(pf);
	*plen = len;
	return buf;
}
static BYTE* ByteArraySwap( BYTE* buffer, int len )

{

	BYTE* buffer2 = new BYTE[ len ];

	for(int i = 0; i < len; i++)

		buffer2[i] = buffer[len-i-1];
	delete [] buffer;

	return buffer2;

}