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https://issues.apache.org/jira/browse/SSHD-330?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pasi Eronen updated SSHD-330:
-----------------------------
Description:
The shared secret returned by KeyAgreement.generateSecret() is a byte array,
which can (by chance, roughly 1 out of 256 times) begin with zero byte. In SSH,
the shared secret is an integer, so we need to strip the leading zero(es).
Some JCE providers might strip leading zeroes, though. SunJCE used to do this
in Java 6, I think, but not anymore in Java 7 -- and there was an almost
identical bug (handshake fails 1 out of 256 times) in Java's SSL/TLS
implementation in early Java 7 versions (see
http://bugs.java.com/view_bug.do?bug_id=8014618).
Pull request here:
https://github.com/apache/mina-sshd/pull/5
How to reproduce with OpenSSH client (assuming Mina SSH server running in port
9922):
for x in {1..500}; do sshpass -p wrong ssh -p9922
-oKexAlgorithms=diffie-hellman-group-exchange-sha1 someuser@localhost; done
for x in {1..500}; do sshpass -p wrong ssh -p9922
-oKexAlgorithms=ecdh-sha2-nistp256 someuser@localhost; done
was:
The shared secret returned by KeyAgreement.generateSecret() is a byte array,
which can (by chance, roughly 1 out of 256 times) begin with zero byte. In SSH,
the shared secret is an integer, so we need to strip the leading zero(es).
Some JCE providers might strip leading zeroes, though. SunJCE used to do this
in Java 6, I think, but not anymore in Java 7 -- and there was an almost
identical bug (handshake fails 1 out of 256 times) in Java's SSL/TLS
implementation in early Java 7 versions (see
http://bugs.java.com/view_bug.do?bug_id=8014618).
How to reproduce with OpenSSH client (assuming Mina SSH server running in port
9922):
for x in {1..500}; do sshpass -p wrong ssh -p9922
-oKexAlgorithms=diffie-hellman-group-exchange-sha1 someuser@localhost; done
for x in {1..500}; do sshpass -p wrong ssh -p9922
-oKexAlgorithms=ecdh-sha2-nistp256 someuser@localhost; done
> Handshake fails (wrong shared secret) 1 out of 256 times
> --------------------------------------------------------
>
> Key: SSHD-330
> URL: https://issues.apache.org/jira/browse/SSHD-330
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 0.11.0
> Reporter: Pasi Eronen
>
> The shared secret returned by KeyAgreement.generateSecret() is a byte array,
> which can (by chance, roughly 1 out of 256 times) begin with zero byte. In
> SSH, the shared secret is an integer, so we need to strip the leading
> zero(es).
> Some JCE providers might strip leading zeroes, though. SunJCE used to do this
> in Java 6, I think, but not anymore in Java 7 -- and there was an almost
> identical bug (handshake fails 1 out of 256 times) in Java's SSL/TLS
> implementation in early Java 7 versions (see
> http://bugs.java.com/view_bug.do?bug_id=8014618).
> Pull request here:
> https://github.com/apache/mina-sshd/pull/5
> How to reproduce with OpenSSH client (assuming Mina SSH server running in
> port 9922):
> for x in {1..500}; do sshpass -p wrong ssh -p9922
> -oKexAlgorithms=diffie-hellman-group-exchange-sha1 someuser@localhost; done
> for x in {1..500}; do sshpass -p wrong ssh -p9922
> -oKexAlgorithms=ecdh-sha2-nistp256 someuser@localhost; done
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