posts/common-cryptographic-operations-with-cryptokit/ about andyibanez-com HOT 2 OPEN

I was surprised when I saw we couldn’t derive RSA keys.

CryptoKit seems to be following the approach of other modern crypto libraries like NaCl and libSodium: giving you useful and relatively-safe operations without exposing all the knobs and switches of the underlying crypto primitives. That's a good thing because it's not hard to accidentally weaken or destroy security by using the wrong settings. They also don't care so much about interoperability with every other crypto API; they're more of a closed ecosystem that assumes both ends of the connection use the same library, or at least compatible libraries.

Part of this is that they're picky about what algorithms to support. RSA is very widely used, but it's also very old. It requires much larger keys than elliptic curves (like, 2048 bits vs 256 bits), it runs slower, and it's much more likely to be broken by near-future advances like quantum computers. Other than compatibility, there's no reason to choose it over a modern ECC algorithm like Curve25519.

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Hi Andy,

Thanks for sharing.

1. For AES-GCM How to generate nonce & tag in Swift so that using same key we can decrypt in any cross platform (.net) as well.
2. Is it possible to encrypt plain text using AES-GCM only by key?

Thanks
BM

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