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