public sealed class SHA1withRSA
{

/// <summary>
/// pem SHA1withRSA签名
/// </summary>
/// <param name="content">待签名字符串</param>
/// <param name="privateKey">私钥</param>
/// <param name="input_charset">编码格式</param>
/// <returns>签名后字符串</returns>
public static string sign(string content, string privateKey, string input_charset)
{
byte[] Data = Encoding.GetEncoding(input_charset).GetBytes(content);
RSACryptoServiceProvider rsa = DecodePemPrivateKey(privateKey);
using (var sh = SHA1.Create())
{
byte[] signData = rsa.SignData(Data, sh);
return Convert.ToBase64String(signData);
}

}
/// <summary>
/// pem格式公钥验签
/// </summary>
/// <param name="content">待验签字符串</param>
/// <param name="signedString">签名</param>
/// <param name="publicKey">公钥</param>
/// <param name="input_charset">编码格式</param>
/// <returns>true(通过)，false(不通过)</returns>
public static bool verify(string content, string signedString, string publicKey, string input_charset)
{
bool result = false;
byte[] Data = Encoding.GetEncoding(input_charset).GetBytes(content);
byte[] data = Convert.FromBase64String(signedString);
RSAParameters paraPub = ConvertFromPublicKey(publicKey);
RSACryptoServiceProvider rsaPub = new RSACryptoServiceProvider();
rsaPub.ImportParameters(paraPub);
using (var sh = SHA1.Create())
{
result = rsaPub.VerifyData(Data, sh, data);
return result;
}

}

/// <summary>
/// RSA加密
/// </summary>
/// <param name="publickey"></param>
/// <param name="content"></param>
/// <returns></returns>
public static string encrypt(string publickey, string content)
{
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
byte[] cipherbytes;
rsa.ImportParameters(ConvertFromPublicKey(publickey));
cipherbytes = rsa.Encrypt(Encoding.UTF8.GetBytes(content), false);
return Convert.ToBase64String(cipherbytes);
}

/// <summary>
/// 解密
/// </summary>
/// <param name="resData">加密字符串</param>
/// <param name="privateKey">私钥</param>
/// <param name="input_charset">编码格式</param>
/// <returns>明文</returns>
public static string decryptData(string resData, string privateKey, string input_charset)
{
byte[] DataToDecrypt = Convert.FromBase64String(resData);
string result = "";
for (int j = 0; j < DataToDecrypt.Length / 128; j++)
{
byte[] buf = new byte[128];
for (int i = 0; i < 128; i++)
{

buf[i] = DataToDecrypt[i + 128 * j];
}
result += decrypt(buf, privateKey, input_charset);
}
return result;
}

#region 内部方法

private static string decrypt(byte[] data, string privateKey, string input_charset)
{
string result = "";
RSACryptoServiceProvider rsa = DecodePemPrivateKey(privateKey);
using (var sh = SHA1.Create())
{
byte[] source = rsa.Decrypt(data, false);
char[] asciiChars = new char[Encoding.GetEncoding(input_charset).GetCharCount(source, 0, source.Length)];
Encoding.GetEncoding(input_charset).GetChars(source, 0, source.Length, asciiChars, 0);
result = new string(asciiChars);
//result = ASCIIEncoding.ASCII.GetString(source);
return result;
}

}

private static RSACryptoServiceProvider DecodePemPrivateKey(String pemstr)
{
RSACryptoServiceProvider rsa = DecodeRSAPrivateKey(Convert.FromBase64String(pemstr));
return rsa;
}
private static RSACryptoServiceProvider DecodePrivateKeyInfo(byte[] pkcs8)
{
byte[] SeqOID = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
byte[] seq = new byte[15];

MemoryStream mem = new MemoryStream(pkcs8);
int lenstream = (int)mem.Length;
BinaryReader binr = new BinaryReader(mem); //wrap Memory Stream with BinaryReader for easy reading
byte bt = 0;
ushort twobytes = 0;

try
{
twobytes = binr.ReadUInt16();
if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
binr.ReadByte(); //advance 1 byte
else if (twobytes == 0x8230)
binr.ReadInt16(); //advance 2 bytes
else
return null;

bt = binr.ReadByte();
if (bt != 0x02)
return null;

twobytes = binr.ReadUInt16();

if (twobytes != 0x0001)
return null;

seq = binr.ReadBytes(15); //read the Sequence OID
if (!CompareBytearrays(seq, SeqOID)) //make sure Sequence for OID is correct
return null;

bt = binr.ReadByte();
if (bt != 0x04) //expect an Octet string
return null;

bt = binr.ReadByte(); //read next byte, or next 2 bytes is 0x81 or 0x82; otherwise bt is the byte count
if (bt == 0x81)
binr.ReadByte();
else
if (bt == 0x82)
binr.ReadUInt16();
//------ at this stage, the remaining sequence should be the RSA private key

byte[] rsaprivkey = binr.ReadBytes((int)(lenstream - mem.Position));
RSACryptoServiceProvider rsacsp = DecodeRSAPrivateKey(rsaprivkey);
return rsacsp;
}

catch (Exception)
{
return null;
}

finally { binr.Dispose(); }

}

private static bool CompareBytearrays(byte[] a, byte[] b)
{
if (a.Length != b.Length)
return false;
int i = 0;
foreach (byte c in a)
{
if (c != b[i])
return false;
i++;
}
return true;
}

private static RSACryptoServiceProvider DecodeRSAPrivateKey(byte[] privkey)
{
byte[] MODULUS, E, D, P, Q, DP, DQ, IQ;

// --------- Set up stream to decode the asn.1 encoded RSA private key ------
MemoryStream mem = new MemoryStream(privkey);
BinaryReader binr = new BinaryReader(mem); //wrap Memory Stream with BinaryReader for easy reading
byte bt = 0;
ushort twobytes = 0;
int elems = 0;
try
{
twobytes = binr.ReadUInt16();
if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
binr.ReadByte(); //advance 1 byte
else if (twobytes == 0x8230)
binr.ReadInt16(); //advance 2 bytes
else
return null;

twobytes = binr.ReadUInt16();
if (twobytes != 0x0102) //version number
return null;
bt = binr.ReadByte();
if (bt != 0x00)
return null;

//------ all private key components are Integer sequences ----
elems = GetIntegerSize(binr);
MODULUS = binr.ReadBytes(elems);

elems = GetIntegerSize(binr);
E = binr.ReadBytes(elems);

elems = GetIntegerSize(binr);
D = binr.ReadBytes(elems);

elems = GetIntegerSize(binr);
P = binr.ReadBytes(elems);

elems = GetIntegerSize(binr);
Q = binr.ReadBytes(elems);

elems = GetIntegerSize(binr);
DP = binr.ReadBytes(elems);

elems = GetIntegerSize(binr);
DQ = binr.ReadBytes(elems);

elems = GetIntegerSize(binr);
IQ = binr.ReadBytes(elems);

// ------- create RSACryptoServiceProvider instance and initialize with public key -----
CspParameters CspParameters = new CspParameters();
CspParameters.Flags = CspProviderFlags.UseMachineKeyStore;
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(1024, CspParameters);
RSAParameters RSAparams = new RSAParameters();
RSAparams.Modulus = MODULUS;
RSAparams.Exponent = E;
RSAparams.D = D;
RSAparams.P = P;
RSAparams.Q = Q;
RSAparams.DP = DP;
RSAparams.DQ = DQ;
RSAparams.InverseQ = IQ;
RSA.ImportParameters(RSAparams);
return RSA;
}
catch
{
return null;
}
finally
{
binr.Dispose();
}
}

private static int GetIntegerSize(BinaryReader binr)
{
byte bt = 0;
byte lowbyte = 0x00;
byte highbyte = 0x00;
int count = 0;
bt = binr.ReadByte();
if (bt != 0x02) //expect integer
return 0;
bt = binr.ReadByte();

if (bt == 0x81)
count = binr.ReadByte(); // data size in next byte
else
if (bt == 0x82)
{
highbyte = binr.ReadByte(); // data size in next 2 bytes
lowbyte = binr.ReadByte();
byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
count = BitConverter.ToInt32(modint, 0);
}
else
{
count = bt; // we already have the data size
}

while (binr.ReadByte() == 0x00)
{ //remove high order zeros in data
count -= 1;
}
binr.BaseStream.Seek(-1, SeekOrigin.Current); //last ReadByte wasn't a removed zero, so back up a byte
return count;
}

#endregion

#region 解析.net 生成的Pem
private static RSAParameters ConvertFromPublicKey(string pemFileConent)
{

if (string.IsNullOrEmpty(pemFileConent))
{
throw new ArgumentNullException("pemFileConent", "This arg cann't be empty.");
}
pemFileConent = pemFileConent.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("\n", "").Replace("\r", "");
byte[] keyData = Convert.FromBase64String(pemFileConent);
bool keySize1024 = (keyData.Length == 162);
bool keySize2048 = (keyData.Length == 294);
if (!(keySize1024 || keySize2048))
{
throw new ArgumentException("pem file content is incorrect, Only support the key size is 1024 or 2048");
}
byte[] pemModulus = (keySize1024 ? new byte[128] : new byte[256]);
byte[] pemPublicExponent = new byte[3];
Array.Copy(keyData, (keySize1024 ? 29 : 33), pemModulus, 0, (keySize1024 ? 128 : 256));
Array.Copy(keyData, (keySize1024 ? 159 : 291), pemPublicExponent, 0, 3);
RSAParameters para = new RSAParameters();
para.Modulus = pemModulus;
para.Exponent = pemPublicExponent;
return para;
}
/// <summary>
/// 将pem格式私钥(1024 or 2048)转换为RSAParameters
/// </summary>
/// <param name="pemFileConent">pem私钥内容</param>
/// <returns>转换得到的RSAParamenters</returns>
private static RSAParameters ConvertFromPrivateKey(string pemFileConent)
{
if (string.IsNullOrEmpty(pemFileConent))
{
throw new ArgumentNullException("pemFileConent", "This arg cann't be empty.");
}
pemFileConent = pemFileConent.Replace("-----BEGIN RSA PRIVATE KEY-----", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("\n", "").Replace("\r", "");
byte[] keyData = Convert.FromBase64String(pemFileConent);

bool keySize1024 = (keyData.Length == 609 || keyData.Length == 610);
bool keySize2048 = (keyData.Length == 1190 || keyData.Length == 1192);

if (!(keySize1024 || keySize2048))
{
throw new ArgumentException("pem file content is incorrect, Only support the key size is 1024 or 2048");
}

int index = (keySize1024 ? 11 : 12);
byte[] pemModulus = (keySize1024 ? new byte[128] : new byte[256]);
Array.Copy(keyData, index, pemModulus, 0, pemModulus.Length);

index += pemModulus.Length;
index += 2;
byte[] pemPublicExponent = new byte[3];
Array.Copy(keyData, index, pemPublicExponent, 0, 3);

index += 3;
index += 4;
if ((int)keyData[index] == 0)
{
index++;
}
byte[] pemPrivateExponent = (keySize1024 ? new byte[128] : new byte[256]);
Array.Copy(keyData, index, pemPrivateExponent, 0, pemPrivateExponent.Length);

index += pemPrivateExponent.Length;
index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
byte[] pemPrime1 = (keySize1024 ? new byte[64] : new byte[128]);
Array.Copy(keyData, index, pemPrime1, 0, pemPrime1.Length);

index += pemPrime1.Length;
index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
byte[] pemPrime2 = (keySize1024 ? new byte[64] : new byte[128]);
Array.Copy(keyData, index, pemPrime2, 0, pemPrime2.Length);

index += pemPrime2.Length;
index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
byte[] pemExponent1 = (keySize1024 ? new byte[64] : new byte[128]);
Array.Copy(keyData, index, pemExponent1, 0, pemExponent1.Length);

index += pemExponent1.Length;
index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
byte[] pemExponent2 = (keySize1024 ? new byte[64] : new byte[128]);
Array.Copy(keyData, index, pemExponent2, 0, pemExponent2.Length);

index += pemExponent2.Length;
index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
byte[] pemCoefficient = (keySize1024 ? new byte[64] : new byte[128]);
Array.Copy(keyData, index, pemCoefficient, 0, pemCoefficient.Length);

RSAParameters para = new RSAParameters();
para.Modulus = pemModulus;
para.Exponent = pemPublicExponent;
para.D = pemPrivateExponent;
para.P = pemPrime1;
para.Q = pemPrime2;
para.DP = pemExponent1;
para.DQ = pemExponent2;
para.InverseQ = pemCoefficient;
return para;
}
#endregion

}