* encrypt/decrypt/sign/verify RSA
* update path-help and doc
* Fix the bug which was breaking convergent encryption
* support both 2048 and 4096
* update doc to contain both 2048 and 4096
* Add test for encrypt, decrypt and rotate on RSA keys
* Support exporting RSA keys
* Add sign and verify test steps
* Remove 'RSA' from PEM header
* use the default salt length
* Add 'RSA' to PEM header since openssl is expecting that
* export rsa keys as signing-key as well
* Comment the reasoning behind the PEM headers
* remove comment
* update comment
* Parameterize hashing for RSA signing and verification
* Added test steps to check hash algo choice for RSA sign/verify
* fix test by using 'prehashed'
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