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using System;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities.Date;
namespace Org.BouncyCastle.Bcpg.OpenPgp
{
/// <remarks>Generator for old style PGP V3 Signatures.</remarks>
public class PgpV3SignatureGenerator
{
private readonly PublicKeyAlgorithmTag keyAlgorithm;
private readonly HashAlgorithmTag hashAlgorithm;
private PgpPrivateKey privKey;
private ISigner sig;
private IDigest dig;
private int signatureType;
private byte lastb;
/// <summary>Create a generator for the passed in keyAlgorithm and hashAlgorithm codes.</summary>
public PgpV3SignatureGenerator(
PublicKeyAlgorithmTag keyAlgorithm,
HashAlgorithmTag hashAlgorithm)
{
if (keyAlgorithm == PublicKeyAlgorithmTag.EdDsa_Legacy)
throw new ArgumentException("Invalid algorithm for V3 signature", nameof(keyAlgorithm));
this.keyAlgorithm = keyAlgorithm;
this.hashAlgorithm = hashAlgorithm;
dig = PgpUtilities.CreateDigest(hashAlgorithm);
}
/// <summary>Initialise the generator for signing.</summary>
public void InitSign(int sigType, PgpPrivateKey privKey)
{
InitSign(sigType, privKey, null);
}
/// <summary>Initialise the generator for signing.</summary>
public void InitSign(int sigType, PgpPrivateKey privKey, SecureRandom random)
{
this.privKey = privKey;
this.signatureType = sigType;
AsymmetricKeyParameter key = privKey.Key;
this.sig = PgpUtilities.CreateSigner(keyAlgorithm, hashAlgorithm, key);
try
{
ICipherParameters cp = key;
cp = ParameterUtilities.WithRandom(cp, random);
sig.Init(true, cp);
}
catch (InvalidKeyException e)
{
throw new PgpException("invalid key.", e);
}
dig.Reset();
lastb = 0;
}
public void Update(byte b)
{
if (signatureType == PgpSignature.CanonicalTextDocument)
{
DoCanonicalUpdateByte(b);
}
else
{
DoUpdateByte(b);
}
}
private void DoCanonicalUpdateByte(byte b)
{
if (b == '\r')
{
DoUpdateCRLF();
}
else if (b == '\n')
{
if (lastb != '\r')
{
DoUpdateCRLF();
}
}
else
{
DoUpdateByte(b);
}
lastb = b;
}
private void DoUpdateCRLF()
{
DoUpdateByte((byte)'\r');
DoUpdateByte((byte)'\n');
}
private void DoUpdateByte(
byte b)
{
sig.Update(b);
dig.Update(b);
}
public void Update(params byte[] b)
{
Update(b, 0, b.Length);
}
public void Update(byte[] b, int off, int len)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
Update(b.AsSpan(off, len));
#else
if (signatureType == PgpSignature.CanonicalTextDocument)
{
int finish = off + len;
for (int i = off; i != finish; i++)
{
DoCanonicalUpdateByte(b[i]);
}
}
else
{
sig.BlockUpdate(b, off, len);
dig.BlockUpdate(b, off, len);
}
#endif
}
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
public void Update(ReadOnlySpan<byte> input)
{
if (signatureType == PgpSignature.CanonicalTextDocument)
{
for (int i = 0; i < input.Length; ++i)
{
DoCanonicalUpdateByte(input[i]);
}
}
else
{
sig.BlockUpdate(input);
dig.BlockUpdate(input);
}
}
#endif
/// <summary>Return the one pass header associated with the current signature.</summary>
public PgpOnePassSignature GenerateOnePassVersion(
bool isNested)
{
return new PgpOnePassSignature(
new OnePassSignaturePacket(signatureType, hashAlgorithm, keyAlgorithm, privKey.KeyId, isNested));
}
/// <summary>Return a V3 signature object containing the current signature state.</summary>
public PgpSignature Generate()
{
long creationTime = DateTimeUtilities.CurrentUnixMs() / 1000L;
byte[] hData = new byte[]
{
(byte) signatureType,
(byte)(creationTime >> 24),
(byte)(creationTime >> 16),
(byte)(creationTime >> 8),
(byte) creationTime
};
sig.BlockUpdate(hData, 0, hData.Length);
dig.BlockUpdate(hData, 0, hData.Length);
byte[] sigBytes = sig.GenerateSignature();
byte[] digest = DigestUtilities.DoFinal(dig);
byte[] fingerPrint = new byte[]{ digest[0], digest[1] };
// an RSA signature
bool isRsa = keyAlgorithm == PublicKeyAlgorithmTag.RsaSign
|| keyAlgorithm == PublicKeyAlgorithmTag.RsaGeneral;
MPInteger[] sigValues = isRsa
? PgpUtilities.RsaSigToMpi(sigBytes)
: PgpUtilities.DsaSigToMpi(sigBytes);
return new PgpSignature(
new SignaturePacket(3, signatureType, privKey.KeyId, keyAlgorithm,
hashAlgorithm, creationTime * 1000L, fingerPrint, sigValues));
}
}
}
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