Question

我有一个创建密钥对的应用程序，并将公钥发送到设备。然后设备加密一些信息，我需要使用我的私钥解密。我生成了一对密钥 String AsymmetricAlgName = Windows.Security.Cryptography.Core.AsymmetricAlgorithmNames.RsaPkcs1;

AsymmetricKeyAlgorithmProvider asym = 
AsymmetricKeyAlgorithmProvider.OpenAlgorithm(AsymmetricAlgName);
CryptographicKey keyPair = asym.CreateKeyPair(2048);

我使用

导出了公钥

IBuffer buffPublicKey = keyPair.ExportPublicKey();
byte[] pubPublickeyBytes;
CryptographicBuffer.CopyToByteArray(buffPublicKey, out pubPublickeyBytes);
string pubKeyStr = Convert.ToBase64String(pubPublickeyBytes);

到目前为止一切顺利。

我的应用程序存储在base64字符串中生成的私钥

IBuffer buffPrivateKeyRsa = keyPair.Export(CryptographicPrivateKeyBlobType.Pkcs1RsaPrivateKey);
CryptographicBuffer.CopyToByteArray(buffPrivateKeyRsa, out pubPrivateBytesRsa);
string priKeyStrRsa = Convert.ToBase64String(pubPrivateBytesRsa);

我有两个问题。

如果我有base64加密字符串， a）如何从base64编码的私钥字符串

b）我如何解密？这一切都在windows商店应用程序中，所以我没有运输其他地方的私钥。我查看了decrypt方法，但它需要一个加密密钥而且我不确定如何从base64编码的字符串中构造它

私钥的base64字符串似乎比公钥长。我不知道这是为什么。公钥和私钥的密钥长度是否应该相同？在任何情况下，这都不会打扰我，但我很好奇

Answer 1

几个小时后，我发现了。

首先，预计私钥64字符串比base64中的公钥长。

其次，API有点有趣（不直观）。要仅导入私钥，您仍需要导入密钥。有导入公钥方法但没有导入私钥方法。

CryptographicKey privKey = asym.ImportKeyPair(CryptographicBuffer.DecodeFromBase64String(priKeyStrRsa), CryptographicPrivateKeyBlobType.Pkcs1RsaPrivateKey);
IBuffer decryptedBuffer = CryptographicEngine.Decrypt(privKey, encryptedBuffer, null);
byte[] decrptedBytes;
CryptographicBuffer.CopyToByteArray(decryptedBuffer, out decrptedBytes);
string data = Encoding.UTF8.GetString(decrptedBytes, 0, decrptedBytes.Length);

首先，您导入一个存储在某个地方的私钥，然后您就可以像这样加密数据

string unencData = "some data";
IBuffer unencCryptBuffer = CryptographicBuffer.CreateFromByteArray(Encoding.UTF8.GetBytes(unencData));
IBuffer publicKeyBuffer = CryptographicBuffer.DecodeFromBase64String(pubKeyStr);
CryptographicKey pubKey = asym.ImportPublicKey(publicKeyBuffer);
IBuffer encryptedBuffer = CryptographicEngine.Encrypt(pubKey, unencCryptBuffer, null);

第三，花费大部分时间让我弄清楚的事情是，我正在与之交谈的一方（硬件设备）正在使用OAEP填充。所以我的解密失败了。这里的诀窍是使用RsaOeapSha1算法。

完整的样本发布在这里

String AsymmetricAlgName = Windows.Security.Cryptography.Core.AsymmetricAlgorithmNames.RsaOaepSha1;
AsymmetricKeyAlgorithmProvider asym = AsymmetricKeyAlgorithmProvider.OpenAlgorithm(AsymmetricAlgName);

CryptographicKey keyPair = asym.CreateKeyPair(2048);
IBuffer buffPublicKey = keyPair.ExportPublicKey();
IBuffer buffPrivateKeyRsa = keyPair.Export(CryptographicPrivateKeyBlobType.Pkcs1RsaPrivateKey);
byte[] pubPublickeyBytes;
byte[] pubPrivateBytesRsa;
CryptographicBuffer.CopyToByteArray(buffPublicKey, out pubPublickeyBytes);
CryptographicBuffer.CopyToByteArray(buffPrivateKeyRsa, out pubPrivateBytesRsa);
string pubKeyStr = Convert.ToBase64String(pubPublickeyBytes);
string priKeyStrRsa = Convert.ToBase64String(pubPrivateBytesRsa);


string unencData = "some data";
IBuffer unencCryptBuffer = CryptographicBuffer.CreateFromByteArray(Encoding.UTF8.GetBytes(unencData));
IBuffer publicKeyBuffer = CryptographicBuffer.DecodeFromBase64String(pubKeyStr);
CryptographicKey pubKey = asym.ImportPublicKey(publicKeyBuffer);
IBuffer encryptedBuffer = CryptographicEngine.Encrypt(pubKey, unencCryptBuffer, null);


CryptographicKey privKey = asym.ImportKeyPair(CryptographicBuffer.DecodeFromBase64String(priKeyStrRsa), CryptographicPrivateKeyBlobType.Pkcs1RsaPrivateKey);
IBuffer decryptedBuffer = CryptographicEngine.Decrypt(privKey, encryptedBuffer, null);
byte[] decrptedBytes;
CryptographicBuffer.CopyToByteArray(decryptedBuffer, out decrptedBytes);
string data = Encoding.UTF8.GetString(decrptedBytes, 0, decrptedBytes.Length);

Windows应用商店使用私钥解密

1 个答案: