SignatureAlgorithm certificate Basic Certificate Field
contains the identifier for the cryptographic algorithm
used by the CA
to sign this certificate
RFC 3279, RFC 4055, and RFC 4491 list supported signature algorithms, but other signature algorithms MAY also be supported.
SignatureAlgorithm is an AlgorithmIdentifier and SHOULD match the AlgorithmIdentifier within the TBSCertificate
There might be more information for this subject on one of the following: