public static unsafe bool TryExportToPem <T>(
T arg,
string label,
TryExportKeyAction <T> exporter,
Span <char> destination,
out int charsWritten)
{
int bufferSize = 4096;
while (true)
{
byte[] buffer = CryptoPool.Rent(bufferSize);
int bytesWritten = 0;
bufferSize = buffer.Length;
// Fixed to prevent GC moves.
fixed(byte *bufferPtr = buffer)
{
try
{
if (exporter(arg, buffer, out bytesWritten))
{
Span <byte> writtenSpan = new Span <byte>(buffer, 0, bytesWritten);
return(PemEncoding.TryWrite(label, writtenSpan, destination, out charsWritten));
}
}
finally
{
CryptoPool.Return(buffer, bytesWritten);
}
bufferSize = checked (bufferSize * 2);
}
}
}
public bool TryExportPkcs7Pem(Span <char> destination, out int charsWritten)
{
byte[]? pkcs7 = Export(X509ContentType.Pkcs7);
if (pkcs7 is null)
{
throw new CryptographicException(SR.Cryptography_X509_ExportFailed);
}
return(PemEncoding.TryWrite(PemLabels.Pkcs7Certificate, pkcs7, destination, out charsWritten));
}
public static void TryWrite_Simple()
{
char[] buffer = new char[1000];
string label = "HELLO";
byte[] content = new byte[] { 0x66, 0x6F, 0x6F };
Assert.True(PemEncoding.TryWrite(label, content, buffer, out int charsWritten));
string pem = new string(buffer, 0, charsWritten);
Assert.Equal("-----BEGIN HELLO-----\nZm9v\n-----END HELLO-----", pem);
}
/// <summary>
/// Attempts to export the public X.509 certificates, encoded as PEM.
/// </summary>
/// <param name="destination">The buffer to receive the PEM encoded certificates.</param>
/// <param name="charsWritten">When this method returns, the total number of characters written to <paramref name="destination" />.</param>
/// <returns>
/// <see langword="true"/> if <paramref name="destination"/> was large enough to receive the encoded PEMs;
/// otherwise, <see langword="false" />.
/// </returns>
/// <exception cref="CryptographicException">
/// A certificate is corrupt, in an invalid state, or could not be exported
/// to PEM.
/// </exception>
/// <remarks>
/// <p>
/// A PEM-encoded X.509 certificate collection will contain certificates
/// where each certificate begins with <c>-----BEGIN CERTIFICATE-----</c>
/// and ends with <c>-----END CERTIFICATE-----</c>, with the base64 encoded DER
/// contents of the certificate between the PEM boundaries. Each certificate is
/// separated by a single line-feed character.
/// </p>
/// <p>
/// Certificates are encoded according to the IETF RFC 7468 "strict"
/// encoding rules.
/// </p>
/// </remarks>
public bool TryExportCertificatePems(Span <char> destination, out int charsWritten)
{
Span <char> buffer = destination;
int written = 0;
for (int i = 0; i < Count; i++)
{
ReadOnlyMemory <byte> certData = this[i].RawDataMemory;
int certSize = PemEncoding.GetEncodedSize(PemLabels.X509Certificate.Length, certData.Length);
// If we ran out of space in the destination, return false. It's okay
// that we may have successfully written data to the destination
// already. Since certificates only contain "public" information,
// we don't need to clear what has been written already.
if (buffer.Length < certSize)
{
charsWritten = 0;
return(false);
}
if (!PemEncoding.TryWrite(PemLabels.X509Certificate, certData.Span, buffer, out int certWritten) ||
certWritten != certSize)
{
Debug.Fail("Presized buffer is too small or did not write the correct amount.");
throw new CryptographicException();
}
buffer = buffer.Slice(certWritten);
written += certWritten;
// write a new line if not the last certificate.
if (i < Count - 1)
{
if (buffer.IsEmpty)
{
charsWritten = 0;
return(false);
}
// Always use Unix line endings between certificates to match the
// behavior of PemEncoding.TryWrite, which is following RFC 7468.
buffer[0] = '\n';
buffer = buffer.Slice(1);
written++;
}
}
charsWritten = written;
return(true);
}
internal static string CreatePemFromData(string label, ReadOnlyMemory <byte> data)
{
int pemSize = PemEncoding.GetEncodedSize(label.Length, data.Length);
return(string.Create(pemSize, (label, data), static (destination, args) =>
{
(string label, ReadOnlyMemory <byte> data) = args;
if (!PemEncoding.TryWrite(label, data.Span, destination, out int charsWritten) ||
charsWritten != destination.Length)
{
Debug.Fail("Pre-allocated buffer was not the correct size.");
throw new CryptographicException();
}
}));
public static unsafe bool TryExportToEncryptedPem <T>(
T arg,
ReadOnlySpan <char> password,
PbeParameters pbeParameters,
TryExportEncryptedKeyAction <T> exporter,
Span <char> destination,
out int charsWritten)
{
int bufferSize = 4096;
while (true)
{
byte[] buffer = CryptoPool.Rent(bufferSize);
int bytesWritten = 0;
bufferSize = buffer.Length;
// Fixed to prevent GC moves.
fixed(byte *bufferPtr = buffer)
{
try
{
if (exporter(arg, password, pbeParameters, buffer, out bytesWritten))
{
Span <byte> writtenSpan = new Span <byte>(buffer, 0, bytesWritten);
return(PemEncoding.TryWrite(PemLabels.EncryptedPkcs8PrivateKey, writtenSpan, destination, out charsWritten));
}
}
finally
{
CryptoPool.Return(buffer, bytesWritten);
}
bufferSize = checked (bufferSize * 2);
}
}
}