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v2fly/common/crypto/internal/chacha_core_gen.go
2017-01-03 14:23:55 +01:00

70 lines
1.8 KiB
Go

// +build generate
package main
import (
"fmt"
"log"
"os"
)
func writeQuarterRound(file *os.File, a, b, c, d int) {
add := "x%d+=x%d\n"
xor := "x=x%d^x%d\n"
rotate := "x%d=(x << %d) | (x >> (32 - %d))\n"
fmt.Fprintf(file, add, a, b)
fmt.Fprintf(file, xor, d, a)
fmt.Fprintf(file, rotate, d, 16, 16)
fmt.Fprintf(file, add, c, d)
fmt.Fprintf(file, xor, b, c)
fmt.Fprintf(file, rotate, b, 12, 12)
fmt.Fprintf(file, add, a, b)
fmt.Fprintf(file, xor, d, a)
fmt.Fprintf(file, rotate, d, 8, 8)
fmt.Fprintf(file, add, c, d)
fmt.Fprintf(file, xor, b, c)
fmt.Fprintf(file, rotate, b, 7, 7)
}
func writeChacha20Block(file *os.File) {
fmt.Fprintln(file, `
func ChaCha20Block(s *[16]uint32, out []byte, rounds int) {
var x0,x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,x13,x14,x15 = s[0],s[1],s[2],s[3],s[4],s[5],s[6],s[7],s[8],s[9],s[10],s[11],s[12],s[13],s[14],s[15]
for i := 0; i < rounds; i+=2 {
var x uint32
`)
writeQuarterRound(file, 0, 4, 8, 12)
writeQuarterRound(file, 1, 5, 9, 13)
writeQuarterRound(file, 2, 6, 10, 14)
writeQuarterRound(file, 3, 7, 11, 15)
writeQuarterRound(file, 0, 5, 10, 15)
writeQuarterRound(file, 1, 6, 11, 12)
writeQuarterRound(file, 2, 7, 8, 13)
writeQuarterRound(file, 3, 4, 9, 14)
fmt.Fprintln(file, "}")
for i := 0; i < 16; i++ {
fmt.Fprintf(file, "binary.LittleEndian.PutUint32(out[%d:%d], s[%d]+x%d)\n", i*4, i*4+4, i, i)
}
fmt.Fprintln(file, "}")
fmt.Fprintln(file)
}
func main() {
file, err := os.OpenFile("chacha_core.generated.go", os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
if err != nil {
log.Fatalf("Failed to generate chacha_core.go: %v", err)
}
defer file.Close()
fmt.Fprintln(file, "package internal")
fmt.Fprintln(file)
fmt.Fprintln(file, "import \"encoding/binary\"")
fmt.Fprintln(file)
writeChacha20Block(file)
}