# Srash64: The Fast Secure Random Number Generator Function

Douglas Crockford
2017-07-24

Srash64 might be a secure random number generator function.

It is an adaptation of Fash256.

This is an implementation in a mythical language.

```def prime_11 := 11111111111111111027
def prime_9 := 9999999999999999961
def prime_8 := 8888888888888888881
def prime_7 := 7777777777777777687
def prime_6 := 6666666666666666619
def prime_5 := 5555555555555555533
def prime_4 := 4444444444444444409
def prime_3 := 3333333333333333271

# The state of the random number generator function is kept in 17 variables.

var a_product: uint64
var a_sum: uint64
var b_product: uint64
var b_sum: uint64
var c_product: uint64
var c_sum: uint64
var d_product: uint64
var d_sum: uint64
var e_product: uint64
var e_sum: uint64
var f_product: uint64
var f_sum: uint64
var g_product: uint64
var g_sum: uint64
var h_product: uint64
var h_sum: uint64
var counter: uint64

def srash64_seed(seeds: array of 16 uint64) {

# The srash64_seed function initializes the srash64 rng function's state.
# The seed contains 1024 bits.

a_product := seeds[0]
a_sum := seeds[1]
b_product := seeds[2]
b_sum := seeds[3]
c_product := seeds[4]
c_sum := seeds[5]
d_product := seeds[6]
d_sum := seeds[7]
e_product := seeds[8]
e_sum := seeds[9]
f_product := seeds[10]
f_sum := seeds[11]
g_product := seeds[12]
g_sum := seeds[13]
h_product := seeds[14]
h_sum := seeds[15]
counter := 0
}

def srash64() {
var a_high: uint64
var b_high: uint64
var c_high: uint64
var d_high: uint64
var e_high: uint64
var f_high: uint64
var g_high: uint64
var h_high: uint64

var a_low: uint64
var b_low: uint64
var c_low: uint64
var d_low: uint64
var e_low: uint64
var f_low: uint64
var g_low: uint64
var h_low: uint64

a_high ; a_low := (a_product xor counter) * prime_11
b_high ; b_low := b_product * prime_9
c_high ; c_low := c_product * prime_8
d_high ; d_low := d_product * prime_7
e_high ; e_low := e_product * prime_6
f_high ; f_low := f_product * prime_5
g_high ; g_low := g_product * prime_4
h_high ; h_low := h_product * prime_3

counter += 1

a_sum += a_high
b_sum += b_high
c_sum += c_high
d_sum += d_high
e_sum += e_high
f_sum += f_high
g_sum += g_high
h_sum += h_high

a_product := a_low xor h_sum
b_product := b_low xor a_sum
c_product := c_low xor b_sum
d_product := d_low xor c_sum
e_product := e_low xor d_sum
f_product := f_low xor e_sum
g_product := g_low xor f_sum
h_product := h_low xor g_sum

return (
((a_product + e_product) xor (b_product + f_product))
+ ((c_product + g_product) xor (d_product + h_product))
)
}
```