DSASignatureDeformatter.cs

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using System.Runtime.Versioning;
 
namespace System.Security.Cryptography;
 
[UnsupportedOSPlatform("browser")]
public class DSASignatureDeformatter : AsymmetricSignatureDeformatter
{
    private DSA _dsaKey;
 
    public DSASignatureDeformatter()
    {
    }
 
    public DSASignatureDeformatter(AsymmetricAlgorithm key)
        : this()
    {
        if (key == null)
        {
            throw new ArgumentNullException("key");
        }
        _dsaKey = (DSA)key;
    }
 
    public override void SetKey(AsymmetricAlgorithm key)
    {
        if (key == null)
        {
            throw new ArgumentNullException("key");
        }
        _dsaKey = (DSA)key;
    }
 
    public override void SetHashAlgorithm(string strName)
    {
        if (strName.ToUpperInvariant() != "SHA1")
        {
            throw new CryptographicUnexpectedOperationException(System.SR.Cryptography_InvalidOperation);
        }
    }
 
    public override bool VerifySignature(byte[] rgbHash, byte[] rgbSignature)
    {
        if (rgbHash == null)
        {
            throw new ArgumentNullException("rgbHash");
        }
        if (rgbSignature == null)
        {
            throw new ArgumentNullException("rgbSignature");
        }
        if (_dsaKey == null)
        {
            throw new CryptographicUnexpectedOperationException(System.SR.Cryptography_MissingKey);
        }
        return _dsaKey.VerifySignature(rgbHash, rgbSignature);
    }
}