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6

Any generation will consume CPU, but it is rather unlikely that you will find that it slows down a modern smart phone. Of the known algorithms - barring post-quantum cryptography - common two-prime RSA has the most CPU intense generation technique as it needs to find two large primes. However, RSA key pairs are normally used as long term, static key pairs. ...


4

In both RSA and usual¹ Elliptic Curve Cryptography (ECC), there is a public key and a private key, forming a matching pair. In signature, the private key is used for signature generation, and the matching public key is used for signature verification. In (usually, hybrid) encryption, the public key is used for encryption, and the matching private key is used ...


4

Although there is an answer here saying "no" for usual definitions, I want to strongly warn that there is no rigorous basis for that. Specifically, it is true that there is no known way of recovering a private key from an encryption of it with its associated public key. However, there is also no proof whatsoever that it isn't possible. Security of ...


3

With RSA or ECC, if I encrypt my private key with my public key, is there a way to recover my private key? No, at least for usual or safe definitions of encrypt: anything involving hybrid encryption (ECIES…) or random padding (RSAES-OAEP in ECB mode¹, likely RSAES-PKCS1-v1_5…). Argument (not a formal proof, but still strong): without the private key, we can'...


3

It is a mistake to think that the RSA keys can be interchanged. In all real systems the RSA public exponent is very small or even directly known. That means all the public key properties are known if the private key is known, as the private key contains the modulus - the only other part of that makes up the public key. I'm not sure why you call the ...


2

If you mean symmetric keys, generation does not require much CPU resources. Usually, operating system provides some source of entropy. Generation of a key based on this is trivial. Keys for asymmetric schemes are based on prime numbers. The essential part of key generation is generation of prime numbers. Many devices (PCs, laptops, tablets, smartphones) use ...


2

In TLS 1.2 the Client proposes a list of suites of primitives they are willing to use for TLS. This takes place in clear in the ClientHello message. You could examine that list and decide one of three things: The list has a nice modern Forward Secret Diffie-Hellman-style key agreement method you're comfortable using with RSA signatures. You present ...


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