Changes private key password.
If more than one key pairs exist with the supplied userId, only the first one is affected.

This method is equivalent to the GnuPG commands:
gpg --edit-key [userId]
Command>passwd

public virtual bool ChangePrivateKeyPassword(
	string userId,
	string oldPassword,
	string newPassword
)

Public Overridable Function ChangePrivateKeyPassword ( _
	userId As String, _
	oldPassword As String, _
	newPassword As String _
) As Boolean

public:
virtual bool ChangePrivateKeyPassword(
	String^ userId, 
	String^ oldPassword, 
	String^ newPassword
)