The X.509 certificate chain used by this service contains certificates with RSA keys shorter than 1024 bits.
Description
At least one of the X.509 certificates sent by the remote host has a key that is shorter than 1024 bits. Such keys are considered weak due to advances in available computing power decreasing the time required to factor cryptographic keys. Some SSL implementations, notably Microsoft's, may consider this SSL chain to be invalid due to the length of one or more of the RSA keys it contains.
Solution
Replace the certificate in the chain with the weak RSA key with a stronger key, and reissue any certificates it signed.