Almost all modern crypto libraries avoid allocation. NaCl (https://nacl.cr.yp.to/ https://nacl.cr.yp.to/), TweetNaCl (https://tweetnacl.cr.yp.to/ https://tweetn

Almost all modern crypto libraries avoid allocation. NaCl (https://nacl.cr.yp.to/ https://nacl.cr.yp.to/), TweetNaCl (https://tweetnacl.cr.yp.to/ https://tweetnacl.cr.yp.to/), Libsodium (https://libsodium.org https://libsodium.org) (except for Argon2), Monocypher (https://monocypher.org https://monocypher.org) (even for argon 2, though users will never allocate hundreds of megabytes on the stack)… From a systems point of view, the fact that modern crypto doesn't require heap allocations makes it one of the easiest domains to work with. (The maths are exacting, but the good APIs are a joy to use).