Table of Contents¶

1 Implementing the ChaCha Pseudo-Random Number Generator (PNRG) in Julia

1.1 Implementation

1.1.1 Preliminary functions

1.2 Examples

1.3 Tests

Implementing the ChaCha Pseudo-Random Number Generator (PNRG) in Julia¶

This post is inspired by this recent blog post by John D. Cook,
The reference is the official reference, the RFC-8439,
Author: Lilian Besson,
License: MIT License
Date: 4th of March, 2019.

Implementation¶

Preliminary functions¶

In [30]:

2 ^ 32, 1 << 32, 2 << 31

Out[30]:

(4294967296, 4294967296, 4294967296)

In [10]:

@time 1 << 31
@time 2 ^ 31

  0.000010 seconds (5 allocations: 176 bytes)
  0.000127 seconds (5 allocations: 176 bytes)

Out[10]:

2147483648

In [37]:

function roll(x, n)
    return (x << n) % (1 << 32) + (x >> (32 - n))
end

Out[37]:

roll (generic function with 1 method)

We can test our operation:

In [39]:

a = 0x11111111
b = 0x01020304
c = 0x77777777
d = 0x01234567
println(c + d)
println(0x789abcde)
c = c + d
println(xor(b, c))
println(0x7998bfda)
b = xor(b, c)
println(roll(b, 7))
println(0xcc5fed3c)

Now the "quarter round" is implemented like this:

In [48]:

function quarter_round(a, b, c, d)
    a = (a + b) % (1 << 32)
    d = roll(xor(d, a), 16)
    c = (c + d) % (1 << 32)
    b = roll(xor(b, c), 12)
    a = (a + b) % (1 << 32)
    d = roll(xor(d, a),  8)
    c = (c + d) % (1 << 32)
    b = roll(xor(b, c),  7)
    return a, b, c, d
end

Out[48]:

quarter_round (generic function with 2 methods)

In [49]:

a = 0x11111111
b = 0x01020304
c = 0x9b8d6f43
d = 0x01234567

quarter_round(a, b, c, d)

Out[49]:

(0x00000000ea2a92f4, 0x00000000cb1cf8ce, 0x000000004581472e, 0x000000005881c4bb)

In [50]:

typeof(a)

Out[50]:

UInt32

In [51]:

0xea2a92f4, 0xcb1cf8ce, 0x4581472e, 0x5881c4bb

Out[51]:

(0xea2a92f4, 0xcb1cf8ce, 0x4581472e, 0x5881c4bb)

Examples¶

In [ ]:

Tests¶

In [ ]: