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//
// System.Security.Cryptography AsymmetricAlgorithm Class implementation
//
// Authors:
// Thomas Neidhart (tome@sbox.tugraz.at)
//
using System;
namespace System.Security.Cryptography {
/// <summary>
/// Abstract base class for all cryptographic asymmetric algorithms.
/// Available algorithms include:
/// RSA, DSA
/// </summary>
public abstract class AsymmetricAlgorithm {
protected int KeySizeValue; // The size of the secret key used by the symmetric algorithm in bits.
protected KeySizes[] LegalKeySizesValue; // Specifies the key sizes that are supported by the symmetric algorithm.
/// <summary>
/// Called from constructor of derived class.
/// </summary>
protected AsymmetricAlgorithm () {
throw new CryptographicException();
}
/// <summary>
/// Gets the key exchange algorithm
/// </summary>
public abstract string KeyExchangeAlgorithm {get;}
/// <summary>
/// Gets or sets the actual key size
/// </summary>
public virtual int KeySize {
get {
return this.KeySizeValue;
}
set {
if (!IsLegalKeySize(this.LegalKeySizesValue, value))
throw new CryptographicException("key size not supported by algorithm");
this.KeySizeValue = value;
}
}
/// <summary>
/// Gets all legal key sizes
/// </summary>
public virtual KeySizes[] LegalKeySizes {
get {
return this.LegalKeySizesValue;
}
}
/// <summary>
/// Gets the signature algorithm
/// </summary>
public abstract string SignatureAlgorithm {get;}
/// <summary>
/// Reconstructs the AsymmetricAlgorithm Object from an XML-string
/// </summary>
public abstract void FromXmlString(string xmlString);
/// <summary>
/// Returns an XML string representation the current AsymmetricAlgorithm object
/// </summary>
public abstract string ToXmlString(bool includePrivateParameters);
private bool IsLegalKeySize(KeySizes[] LegalKeys, int Size) {
foreach (KeySizes LegalKeySize in LegalKeys) {
for (int i=LegalKeySize.MinSize; i<=LegalKeySize.MaxSize; i+=LegalKeySize.SkipSize) {
if (i == Size)
return true;
}
}
return false;
}
/// <summary>
/// Checks wether the given keyLength is valid for the current algorithm
/// </summary>
/// <param name="bitLength">the given keyLength</param>
public bool ValidKeySize(int bitLength) {
return IsLegalKeySize(LegalKeySizesValue, bitLength);
}
/// <summary>
/// Creates the default implementation of the default asymmetric algorithm (RSA).
/// </summary>
public static AsymmetricAlgorithm Create () {
return RSA.Create();;
}
/// <summary>
/// Creates a specific implementation of the given asymmetric algorithm.
/// </summary>
/// <param name="algName">the given algorithm</param>
[MonoTODO]
public static AsymmetricAlgorithm Create (string algName) {
// TODO: use reflection to create a new instance of the given algorithm
return null;
}
}
}
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