From e377daf598853e5ac3b1b74ff1f1151f605ced47 Mon Sep 17 00:00:00 2001
From: Rob McMullen <feedback@playermissile.com>
Date: Tue, 29 Aug 2017 08:25:27 -0700
Subject: [PATCH] Added brute-force random seed generator for the ADC/XOR
 simple random number generator

---
 gen_random_seeds.py | 153 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100755 gen_random_seeds.py

diff --git a/gen_random_seeds.py b/gen_random_seeds.py
new file mode 100755
index 0000000..349d2d1
--- /dev/null
+++ b/gen_random_seeds.py
@@ -0,0 +1,153 @@
+#!/usr/bin/env python
+
+import numpy as np
+
+# prng16:
+#     lsr rand+1
+#     ror rand
+#     bcc skip
+#     lda rand+1
+#     ; $60 = 1..32767, see table above
+#     eor #$60
+#     sta rand+1
+# skip:
+#     rts
+
+# rand:
+#     ; seed mustn't be zero!
+#     .byte $01,$00
+
+# lfsr_order = [
+#     (0x03, 0x03, ),
+#     (0x07, 0x06, ),
+#     (0x0f, 0x0c, ),
+#     (0x1f, 0x14, ),
+#     (0x3f, 0x30, ),
+#     (0x7f, 0x60, ),
+#     (0xff, 0xb8, ),
+#     ]
+
+# def get_prng(framenum):
+#     if framenum < 0 or framenum > 6:
+#         return []
+#     seed = 0x843f
+#     period, term = lfsr_order[framenum]
+#     order = []
+#     seed = (seed & period) | 0x01
+#     for i in range(period):
+#         rand = seed >> 1
+#         if seed & 0x01:
+#             rand ^= term
+#         #order.append((rand & period) - 1 - period // 2 + 96)
+#         #print("%d seed=%x rand=%x &period=%x" % (i, seed, rand, rand & period))
+#         order.append((rand & period))
+#         seed = rand
+#     return order
+
+
+# adc/xor routine from:
+# https://stackoverflow.com/questions/17411712/finding-seeds-for-a-5-byte-prng
+
+
+adcxor_order = [
+    (3, 0x07, 0x3, 0x7),
+    (4, 0x0f, 0x7, 0xd),
+    (5, 0x1f, 0x9, 0x1f),
+    (6, 0x3f, 0x7, 0x17),
+    (7, 0x7f, 0x15, 0x5b),
+    (8, 0xff, 0x3b, 0x3f),
+]
+
+def get_prng(framenum):
+    if framenum < 0 or framenum > 5:
+        return []
+    BITS, period, num1, num2 = adcxor_order[framenum]
+    order = []
+    r = 0
+    for i in range(period):
+        r=(((r>>(BITS-1)) & 1)+r+r+num1)^num2
+        r&=(1<<(BITS-1)) | ((1<<(BITS-1))-1)
+        order.append(r)
+    return order
+
+adcxor_8bit = [
+   (0x03, 0x045),
+   (0x03, 0x073),
+   (0x03, 0x085),
+   (0x03, 0x0b3),
+   (0x0d, 0x04d),
+   (0x0d, 0x08d),
+   (0x23, 0x033),
+   (0x23, 0x0f3),
+   (0x3b, 0x03f),
+   (0x3b, 0x0ff),
+   (0x45, 0x07f),
+   (0x45, 0x0bf),
+   (0x5d, 0x073),
+   (0x5d, 0x0b3),
+   (0x73, 0x00d),
+   (0x73, 0x0cd),
+   (0x7d, 0x005),
+   (0x7d, 0x033),
+   (0x7d, 0x0c5),
+   (0x7d, 0x0f3),
+   ]
+
+def get_prng8(framenum):
+    num1, num2 = adcxor_8bit[framenum]
+    order = []
+    r = 0
+    BITS = 8
+    for i in range(255):
+        r=(((r>>(BITS-1)) & 1)+r+r+num1)^num2
+        r&=(1<<(BITS-1)) | ((1<<(BITS-1))-1)
+        order.append(r)
+    return order
+
+
+if __name__ == '__main__':
+    gen_16_bit = False
+    summary = False
+
+    if gen_16_bit:
+        random_bits = 16
+    else:
+        random_bits = 8
+
+    valid_seeds = []
+    for BITS in range(2, random_bits + 1):
+        mc = 0
+
+        num1 = 1
+        while True:
+            num2 = 1
+            while True:
+                r = 0
+                c = 0
+                values = []
+                while True:
+                    r=(((r>>(BITS-1)) & 1)+r+r+num1)^num2
+                    r&=(1<<(BITS-1)) | ((1<<(BITS-1))-1)
+                    c += 1
+                    values.append(r)
+                    if r == 0:
+                        break
+                if c == (1 << BITS):
+                    #print("BITS: %d Num1(adc): %04x, Num2(eor): %04x count=%d values=%s" % (BITS, num1, num2, len(values), ",".join("%x" % x for x in values)))
+                    valid_seeds.append((BITS, num1, num2))
+                    print("BITS: %d Num1(adc): %04x, Num2(eor): %04x" % (BITS, num1, num2))
+                # if c >= mc:
+                #     mc = c
+                #     print("BITS: %x Count-1: %04x, Num1(adc): %04x, Num2(eor): %04x\n" % (BITS, c, num1, num2))
+                num2 += 2
+                num2 &= (1<<(BITS-1)) | ((1<<(BITS-1))-1)
+                if num2 == 1:
+                    break
+            num1 += 2
+            num1 &= ((1<<(BITS-1))-1)  # * Do not check complements
+            if num1 == 1:
+                break
+
+    if summary:
+        for bits, num1, num2 in valid_seeds:
+            print("BITS: %d Num1(adc): %04x, Num2(eor): %04x" % (bits, num1, num2))