protected override byte[] SignHash(
KeyDescription key,
byte[] hash,
DSASignatureFormat signatureFormat)
{
ECDsa dsa = (ECDsa)key.Key;
byte[] predictedMax = new byte[dsa.GetMaxSignatureSize(signatureFormat)];
Assert.True(
dsa.TrySignHash(hash, predictedMax, signatureFormat, out int written),
"TrySignHash with a GetMaxSignatureSize buffer");
if (signatureFormat == DSASignatureFormat.IeeeP1363FixedFieldConcatenation)
{
// GetMaxSignatureSize should be exactly accurate for P1363.
Assert.Equal(predictedMax.Length, written);
}
if (written == predictedMax.Length)
{
return(predictedMax);
}
return(predictedMax.AsSpan(0, written).ToArray());
}
public void Rfc23279TrySignHashUnderMax()
{
KeyDescription keyDescription = GetKey();
ECDsa key = (ECDsa)keyDescription.Key;
const DSASignatureFormat SignatureFormat = DSASignatureFormat.Rfc3279DerSequence;
// Make secp521r1 (7/16 chance of being smaller) and mod-8 keys (3/4 chance of being smaller)
// have the same 1-in-a-billion chance of failure.
int retryCount = keyDescription.FieldSizeInBits % 8 == 1 ? 36 : 15;
byte[] hash = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };
int expectedSize = GetExpectedSize(keyDescription.FieldSizeInBits);
int maxSize = key.GetMaxSignatureSize(DSASignatureFormat.Rfc3279DerSequence);
Assert.True(expectedSize < maxSize, "expectedSize < maxSize");
byte[] signature = new byte[expectedSize];
for (int i = 0; i < retryCount; i++)
{
if (key.TrySignHash(hash, signature, SignatureFormat, out int written))
{
return;
}
Assert.Equal(0, written);
}
Assert.True(false, $"TrySignHash eventually succeeds with a {expectedSize}/{maxSize}-byte destination");
}
public void Rfc23279TrySignHashUnderMax()
{
KeyDescription keyDescription = GetKey();
ECDsa key = (ECDsa)keyDescription.Key;
const DSASignatureFormat SignatureFormat = DSASignatureFormat.Rfc3279DerSequence;
const int RetryCount = 10;
byte[] hash = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 };
int expectedSize = GetExpectedSize(keyDescription.FieldSizeInBits);
int maxSize = key.GetMaxSignatureSize(DSASignatureFormat.Rfc3279DerSequence);
Assert.True(expectedSize < maxSize, "expectedSize < maxSize");
byte[] signature = new byte[expectedSize];
for (int i = 0; i < RetryCount; i++)
{
if (key.TrySignHash(hash, signature, SignatureFormat, out int written))
{
return;
}
Assert.Equal(0, written);
}
Assert.True(false, $"TrySignHash eventually succeeds with a {expectedSize}/{maxSize}-byte destination");
}
