Microsoft is making a security-focused policy change that will see RSA keys with lengths shorter than 2048 bits deprecated. RSA keys are algorithms used for secure data encryption and decryption in digital communications, i.e. to encrypt data for secure communications over an enterprise network.
However, with RSA encryption keys becoming vulnerable to advancing cryptographic techniques (driven by advancements in compute power) the decision by Microsoft to depreciate them is being seen as a way to stop organisations from using what is now seen as a weaker method of authentication.
Also, the move by Microsoft will help bring the industry in line with recommendations from the internet standards and regulatory bodies who banned the use of 1024-bit keys in 2013 and recommended that RSA keys should have a key length of 2048 bits or longer.