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|
package secp256k1
import (
crand "crypto/rand"
"io"
mrand "math/rand"
"os"
"strings"
"time"
)
/*
Note:
- On windows cryto/rand uses CrytoGenRandom which uses RC4 which is insecure
- Android random number generator is known to be insecure.
- Linux uses /dev/urandom , which is thought to be secure and uses entropy pool
Therefore the output is salted.
*/
//finalizer from MurmerHash3
func mmh3f(key uint64) uint64 {
key ^= key >> 33
key *= 0xff51afd7ed558ccd
key ^= key >> 33
key *= 0xc4ceb9fe1a85ec53
key ^= key >> 33
return key
}
//knuth hash
func knuth_hash(in []byte) uint64 {
var acc uint64 = 3074457345618258791
for i := 0; i < len(in); i++ {
acc += uint64(in[i])
acc *= 3074457345618258799
}
return acc
}
var _rand *mrand.Rand
func init() {
var seed1 uint64 = mmh3f(uint64(time.Now().UnixNano()))
var seed2 uint64 = knuth_hash([]byte(strings.Join(os.Environ(), "")))
var seed3 uint64 = mmh3f(uint64(os.Getpid()))
_rand = mrand.New(mrand.NewSource(int64(seed1 ^ seed2 ^ seed3)))
}
func saltByte(n int) []byte {
buff := make([]byte, n)
for i := 0; i < len(buff); i++ {
var v uint64 = uint64(_rand.Int63())
var b byte
for j := 0; j < 8; j++ {
b ^= byte(v & 0xff)
v = v >> 8
}
buff[i] = b
}
return buff
}
//On Unix-like systems, Reader reads from /dev/urandom.
//On Windows systems, Reader uses the CryptGenRandom API.
//use entropy pool etc and cryptographic random number generator
//mix in time
//mix in mix in cpu cycle count
func RandByte(n int) []byte {
buff := make([]byte, n)
ret, err := io.ReadFull(crand.Reader, buff)
if len(buff) != ret || err != nil {
return nil
}
buff2 := saltByte(n)
for i := 0; i < n; i++ {
buff[i] ^= buff2[2]
}
return buff
}
/*
On Unix-like systems, Reader reads from /dev/urandom.
On Windows systems, Reader uses the CryptGenRandom API.
*/
func RandByteWeakCrypto(n int) []byte {
buff := make([]byte, n)
ret, err := io.ReadFull(crand.Reader, buff)
if len(buff) != ret || err != nil {
return nil
}
return buff
}
|
