[英]Decrypt a larger text using RSA private key
我必须使用RSA公钥和私钥来加密和解密大字符串。 我已成功使用以下示例代码加密了较大的文本
public static string Encrypt(string publicKey, string data, RsaKeyLengths length)
{
// full array of bytes to encrypt
byte[] bytesToEncrypt;
// worker byte array
byte[] block;
// encrypted bytes
byte[] encryptedBytes;
// length of bytesToEncrypt
var dataLength = 0;
// number of bytes in key
var keySize = 0;
// maximum block length to encrypt
var maxLength = 0;
// how many blocks must we encrypt to encrypt entire message?
var iterations = 0;
// the encrypted data
var encryptedData = new StringBuilder();
// instantiate the crypto provider with the correct key length
var rsaCryptoServiceProvider = new RSACryptoServiceProvider((int)length);
// initialize the RSA object from the given public key
rsaCryptoServiceProvider.FromXmlString(publicKey);
// convert data to byte array
bytesToEncrypt = Encoding.Unicode.GetBytes(data);
// get length of byte array
dataLength = bytesToEncrypt.Length;
// convert length of key from bits to bytes
keySize = (int)length / 8;
// .NET RSACryptoServiceProvider uses SHA1 Hash function
// use this to work out the maximum length to encrypt per block
maxLength = ((keySize - 2) - (2 * SHA1.Create().ComputeHash(bytesToEncrypt).Length));
// how many blocks do we need to encrypt?
iterations = dataLength / maxLength;
// encrypt block by block
for (int index = 0; index <= iterations; index++)
{
// is there more than one full block of data left to encrypt?
if ((dataLength - maxLength * index) > maxLength)
{
block = new byte[maxLength];
}
else
{
block = new byte[dataLength - maxLength * index];
}
// copy the required number of bytes from the array of bytes to encrypt to our worker array
Buffer.BlockCopy(bytesToEncrypt, maxLength * index, block, 0, block.Length);
// encrypt the current worker array block of bytes
encryptedBytes = rsaCryptoServiceProvider.Encrypt(block, true);
// RSACryptoServiceProvider reverses the order of encrypted bytesToEncrypt after encryption and before decryption.
// Undo this reversal for compatibility with other implementations
Array.Reverse(encryptedBytes);
// convert to base 64 string
encryptedData.Append(Convert.ToBase64String(encryptedBytes));
}
return encryptedData.ToString();
}
然后,我尝试使用以下代码解密较大的文本
/// <summary>
/// Encrypt an arbitrary string of data under the supplied public key
/// </summary>
/// <param name="publicKey">The public key to encrypt under</param>
/// <param name="data">The data to encrypt</param>
/// <param name="length">The bit length or strength of the public key: 1024, 2048 or 4096 bits. This must match the
/// value actually used to create the publicKey</param>
/// <returns></returns>
public static string Decrypt(string privateKey, string data, RsaKeyLengths length)
{
// full array of bytes to encrypt
byte[] bytesToDecrypt;
// worker byte array
byte[] block;
// encrypted bytes
byte[] decryptedBytes;
// length of bytesToEncrypt
var dataLength = 0;
// number of bytes in key
var keySize = 0;
// maximum block length to encrypt
var maxLength = 0;
// how many blocks must we encrypt to encrypt entire message?
var iterations = 0;
// the encrypted data
var decryptedData = new StringBuilder();
// instantiate the crypto provider with the correct key length
var rsaCryptoServiceProvider = new RSACryptoServiceProvider((int)length);
// initialize the RSA object from the given public key
rsaCryptoServiceProvider.FromXmlString(privateKey);
// convert data to byte array
bytesToDecrypt = Encoding.Unicode.GetBytes(data);
// get length of byte array
dataLength = bytesToDecrypt.Length;
// convert length of key from bits to bytes
keySize = (int)length / 8;
// .NET RSACryptoServiceProvider uses SHA1 Hash function
// use this to work out the maximum length to encrypt per block
//maxLength = ((keySize - 2) - (2 * SHA1.Create().ComputeHash(bytesToDecrypt).Length));
maxLength = ((keySize / 8) % 3 != 0) ?
(((keySize / 8) / 3) * 4) + 4 : ((keySize / 8) / 3) * 4; ;
// how many blocks do we need to encrypt?
iterations = dataLength / maxLength;
// encrypt block by block
for (int index = 0; index <= iterations; index++)
{
// is there more than one full block of data left to encrypt?
if ((dataLength - maxLength * index) > maxLength)
{
block = new byte[maxLength];
}
else
{
block = new byte[dataLength - maxLength * index];
}
// copy the required number of bytes from the array of bytes to encrypt to our worker array
Buffer.BlockCopy(bytesToDecrypt, maxLength * index, block, 0, block.Length);
// encrypt the current worker array block of bytes
decryptedBytes = rsaCryptoServiceProvider.Decrypt(block, true);
// RSACryptoServiceProvider reverses the order of encrypted bytesToEncrypt after encryption and before decryption.
// Undo this reversal for compatibility with other implementations
Array.Reverse(decryptedBytes);
// convert to base 64 string
decryptedData.Append(Convert.ToBase64String(decryptedBytes));
}
return decryptedData.ToString();
}
实际上,加密正在顺利进行。 没问题。 但是当我试图解密它时。 我收到以下异常
未处理的异常:System.Security.Cryptography.CryptographicException:解码OAEP填充时发生错误。
有人可以帮我吗?
请改用流密码,并且仅使用RSA对此密码加密该密钥。 如果由于RSA的公私钥逻辑而需要RSA,并且想使用不同的密钥进行加密和解密,这可能会有所帮助。 使用流密码,您将能够加密和解密千兆字节的数据。
RSA通常不用于大量数据。
也许有些晚,但是我发现http://tekaris.com/blog/2013/02/08/encrypting-large-data-with-asymetric-rsacryptoserviceprovider/很有帮助。 显然,这里的窍门是拆分数据,加密并重新加入数据。
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