HashMembershipCondition.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Security / Policy / HashMembershipCondition.cs / 1 / HashMembershipCondition.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 

// 
// HashMembershipCondition.cs 
//
// Implementation of membership condition for hashes of assemblies. 
//

namespace System.Security.Policy {
    using System.Collections; 
    using System.Runtime.Serialization;
    using System.Security; 
    using System.Security.Cryptography; 
    using System.Security.Util;
    using System.Threading; 
    using System.Globalization;

    [Serializable]
    [System.Runtime.InteropServices.ComVisible(true)] 
    public sealed class HashMembershipCondition : ISerializable, IDeserializationCallback, IMembershipCondition {
        private byte[] m_value = null; 
        private HashAlgorithm m_hashAlg = null; 
        private SecurityElement m_element = null;
 
        private object s_InternalSyncObject = null;
        private object InternalSyncObject {
            get {
                if (s_InternalSyncObject == null) { 
                    Object o = new Object();
                    Interlocked.CompareExchange(ref s_InternalSyncObject, o, null); 
                } 
                return s_InternalSyncObject;
            } 
        }

        internal HashMembershipCondition() {}
        private HashMembershipCondition (SerializationInfo info, StreamingContext context) { 
            m_value = (byte[]) info.GetValue("HashValue", typeof(byte[]));
            string hashAlgorithm = (string) info.GetValue("HashAlgorithm", typeof(string)); 
            if (hashAlgorithm != null) 
                m_hashAlg = HashAlgorithm.Create(hashAlgorithm);
            else 
                m_hashAlg = new SHA1Managed();
        }

        public HashMembershipCondition(HashAlgorithm hashAlg, byte[] value) { 
            if (value == null)
                throw new ArgumentNullException("value"); 
            if (hashAlg == null) 
                throw new ArgumentNullException("hashAlg");
 
            m_value = new byte[value.Length];
            Array.Copy(value, m_value, value.Length);
            m_hashAlg = hashAlg;
        } 

        ///  
        void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context) { 
            info.AddValue("HashValue", this.HashValue);
            info.AddValue("HashAlgorithm", this.HashAlgorithm.ToString()); 
        }

        /// 
        void IDeserializationCallback.OnDeserialization (Object sender) {} 

        public HashAlgorithm HashAlgorithm { 
            set { 
                if (value == null)
                    throw new ArgumentNullException("HashAlgorithm"); 
                m_hashAlg = value;
            }
            get {
                if (m_hashAlg == null && m_element != null) 
                    ParseHashAlgorithm();
                return m_hashAlg; 
            } 
        }
 
        public byte[] HashValue {
            set {
                if (value == null)
                    throw new ArgumentNullException("value"); 
                m_value = new byte[value.Length];
                Array.Copy(value, m_value, value.Length); 
            } 
            get {
                if (m_value == null && m_element != null) 
                    ParseHashValue();
                if (m_value == null)
                    return null;
 
                byte[] value = new byte[m_value.Length];
                Array.Copy(m_value, value, m_value.Length); 
                return value; 
            }
        } 

        public bool Check(Evidence evidence) {
            if (evidence == null)
                return false; 

            IEnumerator enumerator = evidence.GetHostEnumerator(); 
            while (enumerator.MoveNext()) { 
                Object obj = enumerator.Current;
                if (obj is Hash) { 
                    if (m_value == null && m_element != null)
                        ParseHashValue();

                    if (m_hashAlg == null && m_element != null) 
                        ParseHashAlgorithm();
 
                    byte[] asmHash = null; 
                    lock (InternalSyncObject) {
                        asmHash = ((Hash)obj).GenerateHash(m_hashAlg); 
                    }

                    if (asmHash != null && CompareArrays(asmHash, m_value))
                        return true; 
                }
            } 
            return false; 
        }
 
        public IMembershipCondition Copy() {
            if (m_value == null && m_element != null)
                ParseHashValue();
 
            if (m_hashAlg == null && m_element != null)
                ParseHashAlgorithm(); 
 
            return new HashMembershipCondition(m_hashAlg, m_value);
        } 

        public SecurityElement ToXml() {
            return ToXml(null);
        } 

        public void FromXml(SecurityElement e) { 
            FromXml(e, null); 
        }
 
        public SecurityElement ToXml(PolicyLevel level) {
            if (m_value == null && m_element != null)
                ParseHashValue();
 
            if (m_hashAlg == null && m_element != null)
                ParseHashAlgorithm(); 
 
            SecurityElement root = new SecurityElement("IMembershipCondition");
            XMLUtil.AddClassAttribute(root, this.GetType(), "System.Security.Policy.HashMembershipCondition"); 
            // If you hit this assert then most likely you are trying to change the name of this class.
            // This is ok as long as you change the hard coded string above and change the assert below.
            BCLDebug.Assert(this.GetType().FullName.Equals("System.Security.Policy.HashMembershipCondition"), "Class name changed!");
 
            root.AddAttribute("version", "1");
            if (m_value != null) 
                root.AddAttribute(s_tagHashValue, Hex.EncodeHexString(HashValue)); 
            if (m_hashAlg != null)
                root.AddAttribute(s_tagHashAlgorithm, HashAlgorithm.GetType().FullName); 
            return root;
        }

        public void FromXml(SecurityElement e, PolicyLevel level) { 
            if (e == null)
                throw new ArgumentNullException("e"); 
 
            if (!e.Tag.Equals("IMembershipCondition"))
                throw new ArgumentException(Environment.GetResourceString("Argument_MembershipConditionElement")); 

            lock (InternalSyncObject) {
                m_element = e;
                m_value = null; 
                m_hashAlg = null;
            } 
        } 

        public override bool Equals(Object o) { 
            HashMembershipCondition that = (o as HashMembershipCondition);
            if (that != null) {
                if (this.m_hashAlg == null && this.m_element != null)
                    this.ParseHashAlgorithm(); 
                if (that.m_hashAlg == null && that.m_element != null)
                    that.ParseHashAlgorithm(); 
 
                if (this.m_hashAlg != null && that.m_hashAlg != null &&
                    this.m_hashAlg.GetType() == that.m_hashAlg.GetType()) { 
                    if (this.m_value == null && this.m_element != null)
                        this.ParseHashValue();
                    if (that.m_value == null && that.m_element != null)
                        that.ParseHashValue(); 

                    if (this.m_value.Length != that.m_value.Length) 
                        return false; 

                    for (int i = 0; i < m_value.Length; i++) { 
                        if (this.m_value[i] != that.m_value[i])
                            return false;
                    }
                    return true; 
                }
            } 
            return false; 
        }
 
        public override int GetHashCode() {
            if (this.m_hashAlg == null && this.m_element != null)
                this.ParseHashAlgorithm();
 
            int accumulator = this.m_hashAlg != null ? this.m_hashAlg.GetType().GetHashCode() : 0;
            if (this.m_value == null && this.m_element != null) 
                this.ParseHashValue(); 

            accumulator = accumulator ^ GetByteArrayHashCode(this.m_value); 
            return accumulator;
        }

        public override string ToString() { 
            if (m_hashAlg == null)
                ParseHashAlgorithm(); 
 
            return String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Hash_ToString"), m_hashAlg.GetType().AssemblyQualifiedName, Hex.EncodeHexString(HashValue));
        } 

        private const string s_tagHashValue = "HashValue";
        private const string s_tagHashAlgorithm = "HashAlgorithm";
 
        private void ParseHashValue() {
            lock (InternalSyncObject) { 
                if (m_element == null) 
                    return;
 
                string elHash = m_element.Attribute(s_tagHashValue);
                if (elHash != null)
                    m_value = Hex.DecodeHexString(elHash);
                else 
                    throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Argument_InvalidXMLElement"), s_tagHashValue, this.GetType().FullName));
 
                if (m_value != null && m_hashAlg != null) { 
                    m_element = null;
                } 
            }
        }

        private void ParseHashAlgorithm() { 
            lock (InternalSyncObject) {
                if (m_element == null) 
                    return; 

                string elHashAlg = m_element.Attribute(s_tagHashAlgorithm); 
                if (elHashAlg != null)
                    m_hashAlg = HashAlgorithm.Create(elHashAlg);
                else
                    m_hashAlg = new SHA1Managed(); 

                if (m_value != null && m_hashAlg != null) 
                    m_element = null; 
            }
        } 

        private static bool CompareArrays(byte[] first, byte[] second) {
            if (first.Length != second.Length)
                return false; 

            int count = first.Length; 
            for (int i = 0; i < count; ++i) { 
                if (first[i] != second[i])
                    return false; 
            }

            return true;
        } 

        private static int GetByteArrayHashCode(byte[] baData) { 
            if (baData == null) 
                return 0;
 
            int accumulator = 0;
            for (int i = 0; i < baData.Length; ++i) {
                accumulator = (accumulator << 8) ^ (int)baData[i] ^ (accumulator >> 24);
            } 
            return accumulator;
        } 
    } 
}

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