Python-RSA version 3.0 has been released. A lot of things have been improved:
Much more secure
Following industrial standard PKCS#1; this means compatibility with OpenSSL
Ability to create and verify detached signatures
More elegant method of encrypting large files
Ability to save and load keys in PEM and DER format
More efficient key generation
Check the Python-RSA page for more information!
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Update: in the mean time 3.0.1 has been released, which removes an import of the "abc" module. This should make the code compatible with Python 2.5 again. All the documentation (including installation instructions) are the same as before.