/// <summary>
/// Compute SHA1 hash for the given input data
/// </summary>
/// <param name="input"></param>
/// <returns>Hash value</returns>
public static string GetSha1(string input)
{
using (var sha1 = System.Security.Cryptography.SHA1.Create())
{
byte[] inputBytes = StringTools.HexStringToByteArray(input);
byte[] hash = sha1.ComputeHash(inputBytes);
StringBuilder sb = new StringBuilder();
for (int i = 0; i < hash.Length; i++)
{
sb.Append(hash[i].ToString("X2"));
}
return(sb.ToString());
}
}
/// <summary>
/// Decrypt data using RSA Asymmetric Block Cipher
/// </summary>
/// <param name="data">The data to decrypt</param>
/// <param name="exponent">The key exponent to use</param>
/// <param name="key">The RSA key to use</param>
/// <returns>The decrypted data</returns>
public string DecryptRsa(string data, string exponent, string key)
{
BigInteger mod = new BigInteger(key, 16);
BigInteger pubExp = new BigInteger(exponent, 16);
RsaKeyParameters pubParameters = new RsaKeyParameters(false, mod, pubExp);
IAsymmetricBlockCipher eng = new RsaEngine();
eng.Init(true, pubParameters);
byte[] encdata = StringTools.HexStringToByteArray(data);
encdata = eng.ProcessBlock(encdata, 0, encdata.Length);
string result = StringTools.ByteArrayToHexString(encdata);
return(result);
}
public static byte[] parseTagLengthData(byte[] data)
{
int index = 0;
List <byte> _tagList = new List <byte>();
while (index < data.Length)
{
var temptag = new List <byte>();
//Get the tag name
temptag.Add(data[index]);
if ((data[index] & EmvConstants.SeeSubsequentBytes) == EmvConstants.SeeSubsequentBytes)
{
index++;
temptag.Add(data[index]);
}
Console.WriteLine("EmvTag " + StringTools.ByteArrayToHexString(temptag.ToArray()));
index++;
// Get the length of the data to follow
if ((data[index] & 0x80) == 0x80)
{
int bytesForLenght = data[index] % 0x80;
index++;
for (int i = 0; i < bytesForLenght; i++)
{
index++;
}
}
else
{
index++;
}
string tagname = StringTools.ByteArrayToHexString(temptag.ToArray()).ToUpper();
if (EmvConstants.PdolTags.ContainsKey(tagname))
{
_tagList.AddRange(StringTools.HexStringToByteArray(EmvConstants.PdolTags[tagname]));
}
else
{
throw new Exception($"Unknown PDOL tag {tagname}");
}
}
return(_tagList.ToArray());
}
/// <summary>
/// <para>Initializer of the certificate object. Parsing and assigning individual fields into properties</para>
/// </summary>
/// <param name="certificate">The certificate to parse in string format.
/// <param name="remainder">The remainder of the certificate.
/// <param name="certificateType">The type (CertificateType) of the certificate.</param>
public EmvCertificate(string certificate, string remainder, CertificateType certificateType)
{
_certificate = certificate;
_remainder = remainder;
_certificateType = certificateType;
Version = byte.Parse(certificate.Substring(0, 2), System.Globalization.NumberStyles.HexNumber);
CType = byte.Parse(certificate.Substring(2, 2), System.Globalization.NumberStyles.HexNumber);
Issuer = StringTools.HexStringToByteArray(certificate.Substring(4, 8));
ExpDate = StringTools.HexStringToByteArray(certificate.Substring(12, 4));
SerialNumber = StringTools.HexStringToByteArray(certificate.Substring(16, 6));
HashAlgIndicator = byte.Parse(certificate.Substring(22, 2), System.Globalization.NumberStyles.HexNumber);
pkAlg = byte.Parse(certificate.Substring(24, 2), System.Globalization.NumberStyles.HexNumber);
pkLength = byte.Parse(certificate.Substring(26, 2), System.Globalization.NumberStyles.HexNumber);
pkExponent = byte.Parse(certificate.Substring(28, 2), System.Globalization.NumberStyles.HexNumber);
int totalLength = pkLength + BeforeKeyLength + HashLength + TrailerLength - (remainder.Length / 2);
HasPadding = (certificate.Length / 2) > totalLength;
int i = 30 + (pkLength * 2) - remainder.Length;
PublicKey = StringTools.HexStringToByteArray(certificate.Substring(30, (pkLength * 2) - remainder.Length) + remainder);
if (HasPadding)
{
Padding = StringTools.HexStringToByteArray(certificate.Substring(30, certificate.Length - totalLength));
i += certificate.Length - totalLength;
}
Hash = StringTools.HexStringToByteArray(certificate.Substring(i, HashLength * 2));
Trailer = byte.Parse(certificate.Substring(i + HashLength * 2, 2), System.Globalization.NumberStyles.HexNumber);
if (certificateType == CertificateType.CA)
{
checkCA();
}
}