diff options
Diffstat (limited to 'crypto/src/asn1/DerBitString.cs')
| -rw-r--r-- | crypto/src/asn1/DerBitString.cs | 242 |
1 files changed, 147 insertions, 95 deletions
diff --git a/crypto/src/asn1/DerBitString.cs b/crypto/src/asn1/DerBitString.cs index 4dabb398f..caf5d6f9f 100644 --- a/crypto/src/asn1/DerBitString.cs +++ b/crypto/src/asn1/DerBitString.cs @@ -13,16 +13,12 @@ namespace Org.BouncyCastle.Asn1 private static readonly char[] table = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; - protected readonly byte[] mData; - protected readonly int mPadBits; - /** * return a Bit string from the passed in object * * @exception ArgumentException if the object cannot be converted. */ - public static DerBitString GetInstance( - object obj) + public static DerBitString GetInstance(object obj) { if (obj == null || obj is DerBitString) { @@ -52,9 +48,7 @@ namespace Org.BouncyCastle.Asn1 * @exception ArgumentException if the tagged object cannot * be converted. */ - public static DerBitString GetInstance( - Asn1TaggedObject obj, - bool isExplicit) + public static DerBitString GetInstance(Asn1TaggedObject obj, bool isExplicit) { Asn1Object o = obj.GetObject(); @@ -63,16 +57,30 @@ namespace Org.BouncyCastle.Asn1 return GetInstance(o); } - return FromAsn1Octets(((Asn1OctetString)o).GetOctets()); + // Not copied because assumed to be a tagged implicit primitive from the parser + return CreatePrimitive(((Asn1OctetString)o).GetOctets()); } + internal readonly byte[] contents; + + public DerBitString(byte data, int padBits) + { + if (padBits > 7 || padBits < 0) + throw new ArgumentException("pad bits cannot be greater than 7 or less than 0", "padBits"); + + this.contents = new byte[] { (byte)padBits, data }; + } + + public DerBitString(byte[] data) + : this(data, 0) + { + } + /** * @param data the octets making up the bit string. * @param padBits the number of extra bits at the end of the string. */ - public DerBitString( - byte[] data, - int padBits) + public DerBitString(byte[] data, int padBits) { if (data == null) throw new ArgumentNullException("data"); @@ -81,42 +89,30 @@ namespace Org.BouncyCastle.Asn1 if (data.Length == 0 && padBits != 0) throw new ArgumentException("if 'data' is empty, 'padBits' must be 0"); - this.mData = Arrays.Clone(data); - this.mPadBits = padBits; - } - - public DerBitString( - byte[] data) - : this(data, 0) - { - } + this.contents = Arrays.Prepend(data, (byte)padBits); + } - public DerBitString( - int namedBits) + public DerBitString(int namedBits) { if (namedBits == 0) { - this.mData = new byte[0]; - this.mPadBits = 0; + this.contents = new byte[]{ 0 }; return; } int bits = BigInteger.BitLen(namedBits); int bytes = (bits + 7) / 8; - Debug.Assert(0 < bytes && bytes <= 4); - byte[] data = new byte[bytes]; - --bytes; + byte[] data = new byte[1 + bytes]; - for (int i = 0; i < bytes; i++) + for (int i = 1; i < bytes; i++) { data[i] = (byte)namedBits; namedBits >>= 8; } Debug.Assert((namedBits & 0xFF) != 0); - data[bytes] = (byte)namedBits; int padBits = 0; @@ -126,17 +122,38 @@ namespace Org.BouncyCastle.Asn1 } Debug.Assert(padBits < 8); + data[0] = (byte)padBits; - this.mData = data; - this.mPadBits = padBits; + this.contents = data; } - public DerBitString( - Asn1Encodable obj) + public DerBitString(Asn1Encodable obj) : this(obj.GetDerEncoded()) { } + internal DerBitString(byte[] contents, bool check) + { + if (check) + { + if (null == contents) + throw new ArgumentNullException("contents"); + if (contents.Length < 1) + throw new ArgumentException("cannot be empty", "contents"); + + int padBits = contents[0]; + if (padBits > 0) + { + if (contents.Length < 2) + throw new ArgumentException("zero length data with non-zero pad bits", "contents"); + if (padBits > 7) + throw new ArgumentException("pad bits cannot be greater than 7 or less than 0", "contents"); + } + } + + this.contents = contents; + } + /** * Return the octets contained in this BIT STRING, checking that this BIT STRING really * does represent an octet aligned string. Only use this method when the standard you are @@ -146,28 +163,27 @@ namespace Org.BouncyCastle.Asn1 */ public virtual byte[] GetOctets() { - if (mPadBits != 0) + if (contents[0] != 0) throw new InvalidOperationException("attempt to get non-octet aligned data from BIT STRING"); - return Arrays.Clone(mData); + return Arrays.CopyOfRange(contents, 1, contents.Length); } public virtual byte[] GetBytes() { - byte[] data = Arrays.Clone(mData); + if (contents.Length == 1) + return Asn1OctetString.EmptyOctets; + int padBits = contents[0]; + byte[] rv = Arrays.CopyOfRange(contents, 1, contents.Length); // DER requires pad bits be zero - if (mPadBits > 0) - { - data[data.Length - 1] &= (byte)(0xFF << mPadBits); - } - - return data; - } + rv[rv.Length - 1] &= (byte)(0xFF << padBits); + return rv; + } public virtual int PadBits { - get { return mPadBits; } + get { return contents[0]; } } /** @@ -177,68 +193,90 @@ namespace Org.BouncyCastle.Asn1 { get { - int value = 0, length = System.Math.Min(4, mData.Length); - for (int i = 0; i < length; ++i) + int value = 0, end = System.Math.Min(5, contents.Length - 1); + for (int i = 1; i < end; ++i) { - value |= (int)mData[i] << (8 * i); + value |= (int)contents[i] << (8 * (i - 1)); } - if (mPadBits > 0 && length == mData.Length) + if (1 <= end && end < 5) { - int mask = (1 << mPadBits) - 1; - value &= ~(mask << (8 * (length - 1))); + int padBits = contents[0]; + byte der = (byte)(contents[end] & (0xFF << padBits)); + value |= (int)der << (8 * (end - 1)); } return value; - } + } } internal override int EncodedLength(bool withID) { - return Asn1OutputStream.GetLengthOfEncodingDL(withID, 1 + mData.Length); + return Asn1OutputStream.GetLengthOfEncodingDL(withID, contents.Length); } internal override void Encode(Asn1OutputStream asn1Out, bool withID) { - if (mPadBits > 0) - { - int last = mData[mData.Length - 1]; - int mask = (1 << mPadBits) - 1; - int unusedBits = last & mask; - - if (unusedBits != 0) - { - byte[] contents = Arrays.Prepend(mData, (byte)mPadBits); + int padBits = contents[0]; + int length = contents.Length; + int last = length - 1; - /* - * X.690-0207 11.2.1: Each unused bit in the final octet of the encoding of a bit string value shall be set to zero. - */ - contents[contents.Length - 1] = (byte)(last ^ unusedBits); + byte lastOctet = contents[last]; + byte lastOctetDer = (byte)(contents[last] & (0xFF << padBits)); - asn1Out.WriteEncodingDL(withID, Asn1Tags.BitString, contents); - return; - } + if (lastOctet == lastOctetDer) + { + asn1Out.WriteEncodingDL(withID, Asn1Tags.BitString, contents); + } + else + { + asn1Out.WriteEncodingDL(withID, Asn1Tags.BitString, contents, 0, last, lastOctetDer); } - - asn1Out.WriteEncodingDL(withID, Asn1Tags.BitString, (byte)mPadBits, mData, 0, mData.Length); } protected override int Asn1GetHashCode() { - return mPadBits.GetHashCode() ^ Arrays.GetHashCode(mData); - } + if (contents.Length < 2) + return 1; + + int padBits = contents[0]; + int last = contents.Length - 1; + + byte lastOctetDer = (byte)(contents[last] & (0xFF << padBits)); - protected override bool Asn1Equals( - Asn1Object asn1Object) + int hc = Arrays.GetHashCode(contents, 0, last); + hc *= 257; + hc ^= lastOctetDer; + return hc; + } + + protected override bool Asn1Equals(Asn1Object asn1Object) { - DerBitString other = asn1Object as DerBitString; + DerBitString that = asn1Object as DerBitString; + if (null == that) + return false; - if (other == null) - return false; + byte[] thisContents = this.contents, thatContents = that.contents; - return this.mPadBits == other.mPadBits - && Arrays.AreEqual(this.mData, other.mData); - } + int length = thisContents.Length; + if (thatContents.Length != length) + return false; + if (length == 1) + return true; + + int last = length - 1; + for (int i = 0; i < last; ++i) + { + if (thisContents[i] != thatContents[i]) + return false; + } + + int padBits = thisContents[0]; + byte thisLastOctetDer = (byte)(thisContents[last] & (0xFF << padBits)); + byte thatLastOctetDer = (byte)(thatContents[last] & (0xFF << padBits)); + + return thisLastOctetDer == thatLastOctetDer; + } - public override string GetString() + public override string GetString() { StringBuilder buffer = new StringBuilder("#"); @@ -254,27 +292,41 @@ namespace Org.BouncyCastle.Asn1 return buffer.ToString(); } - internal static DerBitString FromAsn1Octets(byte[] octets) - { - if (octets.Length < 1) - throw new ArgumentException("truncated BIT STRING detected", "octets"); + internal static int EncodedLength(bool withID, int contentsLength) + { + return Asn1OutputStream.GetLengthOfEncodingDL(withID, contentsLength); + } - int padBits = octets[0]; - byte[] data = Arrays.CopyOfRange(octets, 1, octets.Length); + internal static void Encode(Asn1OutputStream asn1Out, bool withID, byte[] buf, int off, int len) + { + asn1Out.WriteEncodingDL(withID, Asn1Tags.BitString, buf, off, len); + } + + internal static void Encode(Asn1OutputStream asn1Out, bool withID, byte pad, byte[] buf, int off, int len) + { + asn1Out.WriteEncodingDL(withID, Asn1Tags.BitString, pad, buf, off, len); + } + + internal static DerBitString CreatePrimitive(byte[] contents) + { + int length = contents.Length; + if (length < 1) + throw new ArgumentException("truncated BIT STRING detected", "contents"); - if (padBits > 0 && padBits < 8 && data.Length > 0) + int padBits = contents[0]; + if (padBits > 0) { - int last = data[data.Length - 1]; - int mask = (1 << padBits) - 1; + if (padBits > 7 || length < 2) + throw new ArgumentException("invalid pad bits detected", "contents"); - if ((last & mask) != 0) + byte finalOctet = contents[length - 1]; + if (finalOctet != (byte)(finalOctet & (0xFF << padBits))) { - return new BerBitString(data, padBits); + return new BerBitString(contents, false); } } - return new DerBitString(data, padBits); + return new DerBitString(contents, false); } } } - |