Ubuntu: 1484-1: PyCrypto vulnerability
Posted by Benjamin D. Thomas   
Ubuntu PyCrypto improperly created ElGamal encryption keys.
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Ubuntu Security Notice USN-1484-1
June 28, 2012

python-crypto vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 12.04 LTS
- Ubuntu 11.10
- Ubuntu 11.04
- Ubuntu 10.04 LTS

Summary:

PyCrypto improperly created ElGamal encryption keys.

Software Description:
- python-crypto: cryptographic algorithms and protocols for Python

Details:

It was discovered that PyCrypto produced inappropriate prime numbers when
generating ElGamal keys. An attacker could use this flaw to facilitate
brute-forcing of ElGamal encryption keys.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 12.04 LTS:
  python-crypto                   2.4.1-1ubuntu0.1

Ubuntu 11.10:
  python-crypto                   2.3-2ubuntu0.1

Ubuntu 11.04:
  python-crypto                   2.1.0-2ubuntu1.1

Ubuntu 10.04 LTS:
  python-crypto                   2.0.1+dfsg1-4ubuntu2.2

In general, a standard system update will make all the necessary changes.
If PyCrypto was used to generate ElGamal keys, we recommend they be
regenerated.

References:
  http://www.ubuntu.com/usn/usn-1484-1
  CVE-2012-2417

Package Information:
  https://launchpad.net/ubuntu/+source/python-crypto/2.4.1-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/python-crypto/2.3-2ubuntu0.1
  https://launchpad.net/ubuntu/+source/python-crypto/2.1.0-2ubuntu1.1
  https://launchpad.net/ubuntu/+source/python-crypto/2.0.1+dfsg1-4ubuntu2.2