/// <summary>
/// Gets the largest size, in bytes, for a signature produced by this key in the indicated format.
/// </summary>
/// <param name="signatureFormat">The encoding format for a signature.</param>
/// <returns>
/// The largest size, in bytes, for a signature produced by this key in the indicated format.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="signatureFormat"/> is not a known format.
/// </exception>
public int GetMaxSignatureSize(DSASignatureFormat signatureFormat)
{
int fieldSizeBits = KeySize;
if (fieldSizeBits == 0)
{
// Coerce the key/key-size into existence
ExportParameters(false);
fieldSizeBits = KeySize;
// This implementation of ECDsa doesn't set KeySize, we can't
if (fieldSizeBits == 0)
{
throw new NotSupportedException(SR.Cryptography_InvalidKeySize);
}
}
switch (signatureFormat)
{
case DSASignatureFormat.IeeeP1363FixedFieldConcatenation:
return(AsymmetricAlgorithmHelpers.BitsToBytes(fieldSizeBits) * 2);
case DSASignatureFormat.Rfc3279DerSequence:
return(AsymmetricAlgorithmHelpers.GetMaxDerSignatureSize(fieldSizeBits));
default:
throw new ArgumentOutOfRangeException(nameof(signatureFormat));
}
}
/// <summary>
/// Gets the largest size, in bytes, for a signature produced by this key in the indicated format.
/// </summary>
/// <param name="signatureFormat">The encoding format for a signature.</param>
/// <returns>
/// The largest size, in bytes, for a signature produced by this key in the indicated format.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="signatureFormat"/> is not a known format.
/// </exception>
public int GetMaxSignatureSize(DSASignatureFormat signatureFormat)
{
DSAParameters dsaParameters = ExportParameters(false);
int qLength = dsaParameters.Q !.Length;
switch (signatureFormat)
{
case DSASignatureFormat.IeeeP1363FixedFieldConcatenation:
return(qLength * 2);
case DSASignatureFormat.Rfc3279DerSequence:
return(AsymmetricAlgorithmHelpers.GetMaxDerSignatureSize(fieldSizeBits: qLength * 8));
default:
throw new ArgumentOutOfRangeException(nameof(signatureFormat));
}
}