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//
// ASN1Convert.cs: Abstract Syntax Notation 1 convertion routines
//
// Authors:
// Sebastien Pouliot <sebastien@ximian.com>
// Jesper Pedersen <jep@itplus.dk>
//
// (C) 2003 Motus Technologies Inc. (http://www.motus.com)
// (C) 2004 IT+ A/S (http://www.itplus.dk)
// Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections;
using System.Globalization;
using System.Security.Cryptography;
using System.Text;
namespace Mono.Security {
// References:
// a. ITU ASN.1 standards (free download)
// http://www.itu.int/ITU-T/studygroups/com17/languages/
#if INSIDE_CORLIB
internal
#else
public
#endif
#if NET_2_0
static class ASN1Convert {
#else
sealed class ASN1Convert {
private ASN1Convert ()
{
}
#endif
// RFC3280, section 4.2.1.5
// CAs conforming to this profile MUST always encode certificate
// validity dates through the year 2049 as UTCTime; certificate validity
// dates in 2050 or later MUST be encoded as GeneralizedTime.
static public ASN1 FromDateTime (DateTime dt)
{
if (dt.Year < 2050) {
// UTCTIME
return new ASN1 (0x17, Encoding.ASCII.GetBytes (
dt.ToUniversalTime ().ToString ("yyMMddHHmmss",
CultureInfo.InvariantCulture) + "Z"));
}
else {
// GENERALIZEDTIME
return new ASN1 (0x18, Encoding.ASCII.GetBytes (
dt.ToUniversalTime ().ToString ("yyyyMMddHHmmss",
CultureInfo.InvariantCulture) + "Z"));
}
}
static public ASN1 FromInt32 (Int32 value)
{
byte[] integer = BitConverterLE.GetBytes (value);
Array.Reverse (integer);
int x = 0;
while ((x < integer.Length) && (integer [x] == 0x00))
x++;
ASN1 asn1 = new ASN1 (0x02);
switch (x) {
case 0:
asn1.Value = integer;
break;
case 4:
asn1.Value = new byte [1];
break;
default:
byte[] smallerInt = new byte [4 - x];
Buffer.BlockCopy (integer, x, smallerInt, 0, smallerInt.Length);
asn1.Value = smallerInt;
break;
}
return asn1;
}
static public ASN1 FromOid (string oid)
{
if (oid == null)
throw new ArgumentNullException ("oid");
return new ASN1 (CryptoConfig.EncodeOID (oid));
}
static public ASN1 FromUnsignedBigInteger (byte[] big)
{
if (big == null)
throw new ArgumentNullException ("big");
// check for numbers that could be interpreted as negative (first bit)
if (big [0] >= 0x80) {
// in thie cas we add a new, empty, byte (position 0) so we're
// sure this will always be interpreted an unsigned integer.
// However we can't feed it into RSAParameters or DSAParameters
int length = big.Length + 1;
byte[] uinteger = new byte [length];
Buffer.BlockCopy (big, 0, uinteger, 1, length - 1);
big = uinteger;
}
return new ASN1 (0x02, big);
}
static public int ToInt32 (ASN1 asn1)
{
if (asn1 == null)
throw new ArgumentNullException ("asn1");
if (asn1.Tag != 0x02)
throw new FormatException ("Only integer can be converted");
int x = 0;
for (int i=0; i < asn1.Value.Length; i++)
x = (x << 8) + asn1.Value [i];
return x;
}
// Convert a binary encoded OID to human readable string representation of
// an OID (IETF style). Based on DUMPASN1.C from Peter Gutmann.
static public string ToOid (ASN1 asn1)
{
if (asn1 == null)
throw new ArgumentNullException ("asn1");
byte[] aOID = asn1.Value;
StringBuilder sb = new StringBuilder ();
// Pick apart the OID
byte x = (byte) (aOID[0] / 40);
byte y = (byte) (aOID[0] % 40);
if (x > 2) {
// Handle special case for large y if x = 2
y += (byte) ((x - 2) * 40);
x = 2;
}
sb.Append (x.ToString (CultureInfo.InvariantCulture));
sb.Append (".");
sb.Append (y.ToString (CultureInfo.InvariantCulture));
ulong val = 0;
for (x = 1; x < aOID.Length; x++) {
val = ((val << 7) | ((byte) (aOID [x] & 0x7F)));
if ( !((aOID [x] & 0x80) == 0x80)) {
sb.Append (".");
sb.Append (val.ToString (CultureInfo.InvariantCulture));
val = 0;
}
}
return sb.ToString ();
}
static public DateTime ToDateTime (ASN1 time)
{
if (time == null)
throw new ArgumentNullException ("time");
string t = Encoding.ASCII.GetString (time.Value);
// to support both UTCTime and GeneralizedTime (and not so common format)
string mask = null;
switch (t.Length) {
case 11:
mask = "yyMMddHHmmZ"; // illegal I think ... must check
break;
case 13:
// RFC3280: 4.1.2.5.1 UTCTime
int year = Convert.ToInt16 (t.Substring (0, 2), CultureInfo.InvariantCulture);
// Where YY is greater than or equal to 50, the
// year SHALL be interpreted as 19YY; and
// Where YY is less than 50, the year SHALL be
// interpreted as 20YY.
if (year >= 50)
t = "19" + t;
else
t = "20" + t;
mask = "yyyyMMddHHmmssZ";
break;
case 15:
mask = "yyyyMMddHHmmssZ"; // GeneralizedTime
break;
}
return DateTime.ParseExact (t, mask, null);
}
}
}
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