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package org.bouncycastle.crypto.tls;
import java.io.IOException;
import java.io.OutputStream;
import org.bouncycastle.crypto.InvalidCipherTextException;
import org.bouncycastle.crypto.encodings.PKCS1Encoding;
import org.bouncycastle.crypto.engines.RSABlindedEngine;
import org.bouncycastle.crypto.params.ParametersWithRandom;
import org.bouncycastle.crypto.params.RSAKeyParameters;
public class TlsRSAUtils
{
public static byte[] generateEncryptedPreMasterSecret(TlsContext context, RSAKeyParameters rsaServerPublicKey,
OutputStream output) throws IOException
{
/*
* Choose a PremasterSecret and send it encrypted to the server
*/
byte[] premasterSecret = new byte[48];
context.getSecureRandom().nextBytes(premasterSecret);
TlsUtils.writeVersion(context.getClientVersion(), premasterSecret, 0);
PKCS1Encoding encoding = new PKCS1Encoding(new RSABlindedEngine());
encoding.init(true, new ParametersWithRandom(rsaServerPublicKey, context.getSecureRandom()));
try
{
byte[] encryptedPreMasterSecret = encoding.processBlock(premasterSecret, 0, premasterSecret.length);
if (TlsUtils.isSSL(context))
{
// TODO Do any SSLv3 servers actually expect the length?
output.write(encryptedPreMasterSecret);
}
else
{
TlsUtils.writeOpaque16(encryptedPreMasterSecret, output);
}
}
catch (InvalidCipherTextException e)
{
/*
* This should never happen, only during decryption.
*/
throw new TlsFatalAlert(AlertDescription.internal_error);
}
return premasterSecret;
}
/**
* @deprecated {@link TlsEncryptionCredentials#decryptPreMasterSecret(byte[])} is expected to decrypt safely
*/
public static byte[] safeDecryptPreMasterSecret(TlsContext context, TlsEncryptionCredentials encryptionCredentials,
byte[] encryptedPreMasterSecret) throws IOException
{
return encryptionCredentials.decryptPreMasterSecret(encryptedPreMasterSecret);
}
public static byte[] safeDecryptPreMasterSecret(TlsContext context, RSAKeyParameters rsaServerPrivateKey,
byte[] encryptedPreMasterSecret)
{
/*
* RFC 5246 7.4.7.1.
*/
ProtocolVersion clientVersion = context.getClientVersion();
// TODO Provide as configuration option?
boolean versionNumberCheckDisabled = false;
/*
* Generate 48 random bytes we can use as a Pre-Master-Secret, if the
* PKCS1 padding check should fail.
*/
byte[] M = new byte[48];
context.getSecureRandom().nextBytes(M);
try
{
PKCS1Encoding encoding = new PKCS1Encoding(new RSABlindedEngine(), M);
encoding.init(false, new ParametersWithRandom(rsaServerPrivateKey, context.getSecureRandom()));
M = encoding.processBlock(encryptedPreMasterSecret, 0,
encryptedPreMasterSecret.length);
}
catch (Exception e)
{
/*
* This should never happen since the decryption should never throw an exception
* and return a random value instead.
*
* In any case, a TLS server MUST NOT generate an alert if processing an
* RSA-encrypted premaster secret message fails, or the version number is not as
* expected. Instead, it MUST continue the handshake with a randomly generated
* premaster secret.
*/
}
/*
* If ClientHello.client_version is TLS 1.1 or higher, server implementations MUST
* check the version number [..].
*/
if (versionNumberCheckDisabled && clientVersion.isEqualOrEarlierVersionOf(ProtocolVersion.TLSv10))
{
/*
* If the version number is TLS 1.0 or earlier, server
* implementations SHOULD check the version number, but MAY have a
* configuration option to disable the check.
*
* So there is nothing to do here.
*/
} else {
/*
* Note that explicitly constructing the pre_master_secret with the
* ClientHello.client_version produces an invalid master_secret if the client
* has sent the wrong version in the original pre_master_secret.
*/
TlsUtils.writeVersion(clientVersion, M, 0);
}
return M;
}
}
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