x.crypto.chacha20: improves the internals of chacha20, add a bench (#25311)

Author: blackshirt

vlib/x/crypto/chacha20/bench/bench.v

@@ -0,0 +1,57 @@
+// This is a benchmark for`x.crypto.chacha20` encryption and decryption
+//
+// Current output on my tests
+//
+// Chacha20 Encryption
+// -----------
+// Iterations:      10000          Total Duration:   76.045ms      ns/op:       7604       B/op:      4    allocs/op:      2
+//
+// ChaCha20 Decryption
+// -----------
+// Iterations:      10000          Total Duration:   71.275ms      ns/op:       7127       B/op:     11    allocs/op:     14
+//
+// After the patch
+// Chacha20 Encryption
+// -----------
+// Iterations:      10000          Total Duration:   46.833ms      ns/op:       4683       B/op:     11    allocs/op:     11
+//
+// ChaCha20 Decryption
+// -----------
+// Iterations:      10000          Total Duration:   48.242ms      ns/op:       4824       B/op:      3    allocs/op:      4
+//
+import x.benchmark
+import encoding.hex
+import x.crypto.chacha20
+
+// randomly generated key and nonce, 32-bytes of key, 12-bytes of nonce
+const key = hex.decode('9d9603f4fc460e273b80795ea50eab5873c04f589226c7d591b5336feb32fcba')!
+const nonce = hex.decode('9a3c83e4236ea9a2c4e482da')!
+
+const plaintext = 'ChaCha20 encrypt decrypt benchmarking message'.bytes()
+
+// expected ciphertext
+const ciphertext = hex.decode('dbddb264e4c478d96805b2d557649232b4b3f37c51035464d12e3675e5e36ce6f6822b49dd6494ccd5213a89c9')!
+
+fn bench_chacha20_encrypt() ! {
+	_ := chacha20.encrypt(key, nonce, plaintext)!
+}
+
+fn bench_chacha20_decrypt() ! {
+	_ := chacha20.decrypt(key, nonce, ciphertext)!
+}
+
+fn main() {
+	cf := benchmark.BenchmarkDefaults{
+		n: 10000
+	}
+	println('Chacha20 Encryption')
+	println('-----------')
+	mut b0 := benchmark.setup(bench_chacha20_encrypt, cf)!
+	b0.run()
+
+	println('')
+	println('ChaCha20 Decryption')
+	println('-----------')
+	mut b1 := benchmark.setup(bench_chacha20_decrypt, cf)!
+	b1.run()
+}