The remote host is missing an update to python-crypto announced via advisory DSA 2502-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202502-1

It was discovered that that the ElGamal code in PythonCrypto, a collection of cryptographic algorithms and protocols for Python used insecure insufficient prime numbers in key generation, which lead to a weakened signature or public key space, allowing easier brute force attacks on such keys. For the stable distribution (squeeze), this problem has been fixed in version 2.1.0-2+squeeze1. For the unstable distribution (sid), this problem has been fixed in version 2.6-1. We recommend that you upgrade your python-crypto packages. After