// PKCS #1 v.2.1, Section 9.2
// EMSA-PKCS1-v1_5-Encode
static byte[] Encode_v15(HashAlgorithmType algorithm, byte[] hashValue, int emLength)
{
var hashSize = HashAlgorithmProvider.GetHashSize(algorithm);
if (hashValue.Length != (hashSize >> 3))
{
throw new CryptographicException("bad hash length for " + algorithm.ToString());
}
// DigestInfo ::= SEQUENCE {
// digestAlgorithm AlgorithmIdentifier,
// digest OCTET STRING
// }
byte[] t = null;
string oid = HashAlgorithmProvider.GetOID(algorithm);
if (oid != null)
{
ASN1 digestAlgorithm = new ASN1(0x30);
digestAlgorithm.Add(new ASN1(CryptoConfig.EncodeOID(oid)));
digestAlgorithm.Add(new ASN1(0x05)); // NULL
ASN1 digest = new ASN1(0x04, hashValue);
ASN1 digestInfo = new ASN1(0x30);
digestInfo.Add(digestAlgorithm);
digestInfo.Add(digest);
t = digestInfo.GetBytes();
}
else
{
// There are no valid OID, in this case t = hashValue
// This is the case of the MD5SHA hash algorithm
t = hashValue;
}
Buffer.BlockCopy(hashValue, 0, t, t.Length - hashValue.Length, hashValue.Length);
int PSLength = System.Math.Max(8, emLength - t.Length - 3);
// PS = PSLength of 0xff
// EM = 0x00 | 0x01 | PS | 0x00 | T
byte[] EM = new byte [PSLength + t.Length + 3];
EM [1] = 0x01;
for (int i = 2; i < PSLength + 2; i++)
{
EM[i] = 0xff;
}
Buffer.BlockCopy(t, 0, EM, PSLength + 3, t.Length);
return(EM);
}
public static byte[] Encode_v15(HashAlgorithm hash, byte[] hashValue, int emLength)
{
if (hashValue.Length != hash.HashSize >> 3)
{
throw new CryptographicException("bad hash length for " + hash.ToString());
}
string oid = CryptoConfig.MapNameToOID(hash.ToString());
byte[] numArray1;
if (oid != null)
{
ASN1 asn1_1 = new ASN1((byte)48);
asn1_1.Add(new ASN1(CryptoConfig.EncodeOID(oid)));
asn1_1.Add(new ASN1((byte)5));
ASN1 asn1_2 = new ASN1((byte)4, hashValue);
ASN1 asN1 = new ASN1((byte)48);
asN1.Add(asn1_1);
asN1.Add(asn1_2);
numArray1 = asN1.GetBytes();
}
else
{
numArray1 = hashValue;
}
Buffer.BlockCopy((Array)hashValue, 0, (Array)numArray1, numArray1.Length - hashValue.Length, hashValue.Length);
int num = System.Math.Max(8, emLength - numArray1.Length - 3);
byte[] numArray2 = new byte[num + numArray1.Length + 3];
numArray2[1] = (byte)1;
for (int index = 2; index < num + 2; ++index)
{
numArray2[index] = byte.MaxValue;
}
Buffer.BlockCopy((Array)numArray1, 0, (Array)numArray2, num + 3, numArray1.Length);
return(numArray2);
}
public static byte[] Encode_v15(HashAlgorithm hash, byte[] hashValue, int emLength)
{
if (hashValue.Length != hash.HashSize >> 3)
{
throw new CryptographicException("bad hash length for " + hash.ToString());
}
string text = CryptoConfig.MapNameToOID(hash.ToString());
byte[] array;
if (text != null)
{
ASN1 asn = new ASN1(48);
asn.Add(new ASN1(CryptoConfig.EncodeOID(text)));
asn.Add(new ASN1(5));
ASN1 asn2 = new ASN1(4, hashValue);
ASN1 asn3 = new ASN1(48);
asn3.Add(asn);
asn3.Add(asn2);
array = asn3.GetBytes();
}
else
{
array = hashValue;
}
Buffer.BlockCopy(hashValue, 0, array, array.Length - hashValue.Length, hashValue.Length);
int num = Math.Max(8, emLength - array.Length - 3);
byte[] array2 = new byte[num + array.Length + 3];
array2[1] = 1;
for (int i = 2; i < num + 2; i++)
{
array2[i] = byte.MaxValue;
}
Buffer.BlockCopy(array, 0, array2, num + 3, array.Length);
return(array2);
}
