Mastering Internet of Things

Understanding key sizes

When using different algorithms, it might be difficult to evaluate the relative strengths of each, since the key sizes vary (counted in bits). The NSA has made some recommendations for commercial enterprises on the relative strengths of different methods. These can be used as a guideline for how secure the corresponding cipher is, or how "easy" it is to break it (for, or according to, the NSA). They can therefore be considered comparatively of similar strength.

Algorithm	Key size	Usage
RSA	3072	Keys, signatures
Diffie-Hellman	3072	Key exchange
Elliptic Curve	NIST P-384	Key exchange, signatures
SHA	384	Integrity
AES	256	Confidentiality

You can find the NSA recommendations ...