|
public static RSADP ( |
||
| rsa | ||
| c | byte | |
| return | byte[] | |
public static byte[] Decrypt_v15(RSA rsa, byte[] C)
{
int size = rsa.KeySize >> 3;
if (size < 11 || C.Length > size)
{
throw new CryptographicException("decryption error");
}
byte[] c = PKCS1.OS2IP(C);
byte[] numArray1 = PKCS1.I2OSP(PKCS1.RSADP(rsa, c), size);
if (numArray1[0] != (byte)0 || numArray1[1] != (byte)2)
{
return((byte[])null);
}
int index = 10;
while (numArray1[index] != (byte)0 && index < numArray1.Length)
{
++index;
}
if (numArray1[index] != (byte)0)
{
return((byte[])null);
}
int srcOffset = index + 1;
byte[] numArray2 = new byte[numArray1.Length - srcOffset];
Buffer.BlockCopy((Array)numArray1, srcOffset, (Array)numArray2, 0, numArray2.Length);
return(numArray2);
}
public static byte[] Decrypt_v15(RSA rsa, byte[] C)
{
int num = rsa.KeySize >> 3;
if (num < 11 || C.Length > num)
{
throw new CryptographicException("decryption error");
}
byte[] c = PKCS1.OS2IP(C);
byte[] x = PKCS1.RSADP(rsa, c);
byte[] array = PKCS1.I2OSP(x, num);
if (array[0] != 0 || array[1] != 2)
{
return(null);
}
int num2 = 10;
while (array[num2] != 0 && num2 < array.Length)
{
num2++;
}
if (array[num2] != 0)
{
return(null);
}
num2++;
byte[] array2 = new byte[array.Length - num2];
Buffer.BlockCopy(array, num2, array2, 0, array2.Length);
return(array2);
}
public static byte[] Decrypt_OAEP(RSA rsa, HashAlgorithm hash, byte[] C)
{
int size = rsa.KeySize / 8;
int maskLen = hash.HashSize / 8;
if (size < 2 * maskLen + 2 || C.Length != size)
{
throw new CryptographicException("decryption error");
}
byte[] c = PKCS1.OS2IP(C);
byte[] numArray1 = PKCS1.I2OSP(PKCS1.RSADP(rsa, c), size);
byte[] array1 = new byte[maskLen];
Buffer.BlockCopy((Array)numArray1, 1, (Array)array1, 0, array1.Length);
byte[] numArray2 = new byte[size - maskLen - 1];
Buffer.BlockCopy((Array)numArray1, numArray1.Length - numArray2.Length, (Array)numArray2, 0, numArray2.Length);
byte[] array2_1 = PKCS1.MGF1(hash, numArray2, maskLen);
byte[] mgfSeed = PKCS1.xor(array1, array2_1);
byte[] array2_2 = PKCS1.MGF1(hash, mgfSeed, size - maskLen - 1);
byte[] numArray3 = PKCS1.xor(numArray2, array2_2);
byte[] emptyHash = PKCS1.GetEmptyHash(hash);
byte[] array2_3 = new byte[emptyHash.Length];
Buffer.BlockCopy((Array)numArray3, 0, (Array)array2_3, 0, array2_3.Length);
bool flag = PKCS1.Compare(emptyHash, array2_3);
int length = emptyHash.Length;
while (numArray3[length] == (byte)0)
{
++length;
}
int count = numArray3.Length - length - 1;
byte[] numArray4 = new byte[count];
Buffer.BlockCopy((Array)numArray3, length + 1, (Array)numArray4, 0, count);
return(numArray1[0] != (byte)0 || !flag || numArray3[length] != (byte)1 ? (byte[])null : numArray4);
}
public static byte[] Decrypt_OAEP(RSA rsa, HashAlgorithm hash, byte[] C)
{
int num = rsa.KeySize / 8;
int num2 = hash.HashSize / 8;
if (num < 2 * num2 + 2 || C.Length != num)
{
throw new CryptographicException("decryption error");
}
byte[] c = PKCS1.OS2IP(C);
byte[] x = PKCS1.RSADP(rsa, c);
byte[] array = PKCS1.I2OSP(x, num);
byte[] array2 = new byte[num2];
Buffer.BlockCopy(array, 1, array2, 0, array2.Length);
byte[] array3 = new byte[num - num2 - 1];
Buffer.BlockCopy(array, array.Length - array3.Length, array3, 0, array3.Length);
byte[] array4 = PKCS1.MGF1(hash, array3, num2);
byte[] mgfSeed = PKCS1.xor(array2, array4);
byte[] array5 = PKCS1.MGF1(hash, mgfSeed, num - num2 - 1);
byte[] array6 = PKCS1.xor(array3, array5);
byte[] emptyHash = PKCS1.GetEmptyHash(hash);
byte[] array7 = new byte[emptyHash.Length];
Buffer.BlockCopy(array6, 0, array7, 0, array7.Length);
bool flag = PKCS1.Compare(emptyHash, array7);
int num3 = emptyHash.Length;
while (array6[num3] == 0)
{
num3++;
}
int num4 = array6.Length - num3 - 1;
byte[] array8 = new byte[num4];
Buffer.BlockCopy(array6, num3 + 1, array8, 0, num4);
if (array[0] != 0 || !flag || array6[num3] != 1)
{
return(null);
}
return(array8);
}
