tor/changes/ticket29536

  o Minor features (performance, RNG):
    - Tor now constructs a fast secure pseudorandom number generator for
      each thread, to use for cases where performance is critical. This PRNG
      is based on AES-CTR, using a buffering construction similar to
      libottery and the (newer) OpenBSD arc4random() code.  It outperforms
      OpenSSL 1.1.1a's CSPRNG by roughly a factor of 100 for small outputs.
      Although we believe it to be cryptographically strong, we are only
      using it when necessary for reasonable performance. Implements tickets
      29023 and 29536.
Implement code to manage a per-thread instance of crypto_fast_rng() The subsystems API makes this really simple, fortunately. Closes ticket 29536 2019-02-19 21:23:31 +01:00			`o Minor features (performance, RNG):`
			`- Tor now constructs a fast secure pseudorandom number generator for`
			`each thread, to use for cases where performance is critical. This PRNG`
			`is based on AES-CTR, using a buffering construction similar to`
			`libottery and the (newer) OpenBSD arc4random() code. It outperforms`
			`OpenSSL 1.1.1a's CSPRNG by roughly a factor of 100 for small outputs.`
			`Although we believe it to be cryptographically strong, we are only`
			`using it when necessary for reasonable performance. Implements tickets`
			`29023 and 29536.`