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I have prepared a simple TLS PSK client test case based on MockPSKTlsClient by Bouncy Castle.
In the main method I call:
public static void main(String[] args) throws IOException {
SecureRandom random = new SecureRandom();
TlsPSKIdentity identity = new BasicTlsPSKIdentity("Client_identity", Hex.decode("1A1A1A1A1A1A1A1A1A1A1A1A1A1A1A1A"));
Socket socket = new Socket(InetAddress.getLocalHost(), 12345);
TlsClientProtocol proto = new TlsClientProtocol(socket.getInputStream(), socket.getOutputStream(), random);
MockPSKTlsClient client = new MockPSKTlsClient(null, identity);
proto.connect(client);
OutputStream clearOs = proto.getOutputStream();
InputStream clearIs = proto.getInputStream();
clearOs.write("GET / HTTP/1.1\r\n\r\n".getBytes("UTF-8"));
Streams.pipeAll(clearIs, System.out); // why is java.io.EOFException thrown?
}
As you can see, I send a GET / HTTP/1.1 string to the openssl server, which is started as:
# openssl s_server \
-psk 1A1A1A1A1A1A1A1A1A1A1A1A1A1A1A1A \
-psk_hint Client_identity\
-cipher PSK-AES256-CBC-SHA \
-debug -state -nocert -accept 12345 -tls1_2 -www
After that I call Streams.pipeAll() method, which is merely:
public static void pipeAll(InputStream inStr, OutputStream outStr)
throws IOException
{
byte[] bs = new byte[BUFFER_SIZE];
int numRead;
while ((numRead = inStr.read(bs, 0, bs.length)) >= 0) // Why is EOFException thrown?
{
outStr.write(bs, 0, numRead);
}
}
This copies openssl s_server answer to the screen and also surprisingly throws an EOFException at the end:
TLS-PSK client negotiated TLS 1.2
Established session: 68e647e3276f345e82effdb7cc04649f6872d245ae01489c08ed109c5906dd16
HTTP/1.0 200 ok
Content-type: text/html
<HTML><BODY BGCOLOR="#ffffff">
<pre>
s_server -psk 1A1A1A1A1A1A1A1A1A1A1A1A1A1A1A1A -psk_hint Client_identity -cipher PSK-AES256-CBC-SHA -debug -state -nocert -accept 12345 -tls1_2 -www
Secure Renegotiation IS supported
Ciphers supported in s_server binary
TLSv1/SSLv3:PSK-AES256-CBC-SHA
---
Ciphers common between both SSL end points:
PSK-AES256-CBC-SHA
Signature Algorithms: RSA+SHA1:RSA+SHA224:RSA+SHA256:RSA+SHA384:RSA+SHA512:DSA+SHA1:DSA+SHA224:DSA+SHA256:DSA+SHA384:DSA+SHA512:ECDSA+SHA1:ECDSA+SHA224:ECDSA+SHA256:ECDSA+SHA384:ECDSA+SHA512
Shared Signature Algorithms: RSA+SHA1:RSA+SHA224:RSA+SHA256:RSA+SHA384:RSA+SHA512:DSA+SHA1:DSA+SHA224:DSA+SHA256:DSA+SHA384:DSA+SHA512:ECDSA+SHA1:ECDSA+SHA224:ECDSA+SHA256:ECDSA+SHA384:ECDSA+SHA512
---
New, TLSv1/SSLv3, Cipher is PSK-AES256-CBC-SHA
SSL-Session:
Protocol : TLSv1.2
Cipher : PSK-AES256-CBC-SHA
Session-ID: 68E647E3276F345E82EFFDB7CC04649F6872D245AE01489C08ED109C5906DD16
Session-ID-ctx: 01000000
Master-Key: B023F1053230C2938E1D3FD6D73FEB41DEC3FC1068A390FE6DCFD60A6ED666CA2AD0CD1DAD504A087BE322DD2C870C0C
Key-Arg : None
PSK identity: Client_identity
PSK identity hint: Client_identity
SRP username: None
Start Time: 1479312253
Timeout : 7200 (sec)
Verify return code: 0 (ok)
---
13 items in the session cache
0 client connects (SSL_connect())
0 client renegotiates (SSL_connect())
0 client connects that finished
14 server accepts (SSL_accept())
0 server renegotiates (SSL_accept())
13 server accepts that finished
0 session cache hits
0 session cache misses
0 session cache timeouts
0 callback cache hits
0 cache full overflows (128 allowed)
---
no client certificate available
</BODY></HTML>
TLS-PSK client raised alert: fatal(2), internal_error(80)
> Failed to read record
java.io.EOFException
at org.bouncycastle.crypto.tls.TlsProtocol.safeReadRecord(Unknown Source)
at org.bouncycastle.crypto.tls.TlsProtocol.readApplicationData(Unknown Source)
at org.bouncycastle.crypto.tls.TlsInputStream.read(Unknown Source)
at de.afarber.tlspskclient2.Main.pipeAll(Main.java:52)
at de.afarber.tlspskclient2.Main.main(Main.java:44)
Exception in thread "main" java.io.IOException: Internal TLS error, this could be an attack
at org.bouncycastle.crypto.tls.TlsProtocol.failWithError(Unknown Source)
at org.bouncycastle.crypto.tls.TlsProtocol.safeReadRecord(Unknown Source)
at org.bouncycastle.crypto.tls.TlsProtocol.readApplicationData(Unknown Source)
at org.bouncycastle.crypto.tls.TlsInputStream.read(Unknown Source)
at de.afarber.tlspskclient2.Main.pipeAll(Main.java:52)
at de.afarber.tlspskclient2.Main.main(Main.java:44)
My question is: why is EOFException thrown?
Usually InputStream.read() is supposed to return -1 at the end of stream and not throw an exception.
How to detect an end of stream properly, when TLS PSK encryption is used?
In the long term I would like to extend my test case to a program acting as reverse PSK TLS proxy in front of embedded Jetty - and would prefer not to rely on exceptions to detect that the client is done reading or writing.
EOFException is thrown (as of v1.56) because the required close_notify alert was not received. This means that the TLS layer cannot exclude the possibility that the application data was truncated.
Truncation means that the data you received so far was correctly (per the active cipher suite) transmitted, but there may have been more data that you didn't receive. Truncation may be accidental or malicious. For many applications, later data may affect the meaning of earlier data, so a truncation may arbitrarily alter semantics.
For some application protocols, it may be possible to determine that there was no actual truncation (i.e. just missing close_notify) - consider the HTTP Content-Length header, or that some or all of the truncated data might still be usefully accepted - consider a stream of self-delimiting, independent messages. This cannot be done in the TLS layer itself; or rather, it is done by requiring close_notify!
So, EOFException is raised to "[signal] that an end of file or end of stream has been reached unexpectedly during input". At this point the application should conservatively assume the data was truncated, but application-specific mechanisms may yet allow the acceptance of part or all of the data as explained above.
As of (not yet released) v1.57 we have added TlsNoCloseNotifyException as a subclass of EOFException, that will only/always be thrown in this specific case, hopefully allowing for simpler application code.