From 2a12310b25f68208ff0101fce5d0137f267c7394 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bitbucket@bruce-hill.com>
Date: Mon, 30 Jul 2018 14:11:45 -0700
Subject: Switching hashes to use base64 instead of hex.

---
 lib/base64.nom | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 lib/base64.nom

(limited to 'lib/base64.nom')

diff --git a/lib/base64.nom b/lib/base64.nom
new file mode 100644
index 0000000..a5bb9bb
--- /dev/null
+++ b/lib/base64.nom
@@ -0,0 +1,54 @@
+#!/usr/bin/env nomsu -V2.5.5.4
+#
+    This file defines actions for encoding/decoding base 64, as specified in:
+    https://tools.ietf.org/html/rfc4648
+
+%b64_str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
+%reverse_b64 = (%b64_str.%i = (%i - 1) for %i in 1 to (length of %b64_str))
+%reverse_b64."=" = 0
+test:
+    %cases = ["", "Zg==", "Zm8=", "Zm9v", "Zm9vYg==", "Zm9vYmE=", "Zm9vYmFy"]
+    for %len = %encoded in %cases:
+        %plain = "foobar".[1, %len - 1]
+        assume ((base64 %plain) == %encoded) or barf ".."
+            \(quote %plain) base64 encoded to \(quote (base64 %plain)) \
+            ..instead of \(quote %encoded)
+        assume ((base64 decode %encoded) == %plain) or barf ".."
+            \(quote %encoded) base64 decoded to \(quote (base64 decode %encoded)) \
+            ..instead of \(quote %plain)
+
+action [base64 %str, base64 encode %str, %str base64]:
+    %chars = []
+    for %i in 1 to (length of %str) via 3:
+        %bytes = [=lua "\%str:byte(\%i, \(%i + 2))"]
+        add %b64_str.(((%bytes.1 & 252) >> 2) + 1) to %chars
+        if (length of %bytes) is:
+            3:
+                add %b64_str.(((%bytes.1 & 3) << 4) + ((%bytes.2 & 240) >> 4) + 1) to %chars
+                add %b64_str.(((%bytes.2 & 15) << 2) + ((%bytes.3 & 192) >> 6) + 1) to %chars
+                add %b64_str.((%bytes.3 & 63) + 1) to %chars
+            
+            2:
+                add %b64_str.(((%bytes.1 & 3) << 4) + ((%bytes.2 & 240) >> 4) + 1) to %chars
+                add %b64_str.(((%bytes.2 & 15) << 2) + 1) to %chars
+                add "=" to %chars
+            
+            1:
+                add %b64_str.(((%bytes.1 & 3) << 4) + 1) to %chars
+                add "=" to %chars
+                add "=" to %chars
+    
+    return (%chars joined)
+
+action [chr %] (=lua "string.char(\%)")
+action [decode base64 %str, %str base64 decoded, base64 decode %str]:
+    %chars = []
+    for %i in 1 to (length of %str) via 4:
+        %indices = (%reverse_b64.(%str.%) for % in %i to (%i + 3))
+        add (chr ((%indices.1 << 2) + ((%indices.2 & 48) >> 4))) to %chars
+        if (%str.(%i+2) == "="): stop
+        add (chr (((%indices.2 & 15) << 4) + ((%indices.3 & 60) >> 2))) to %chars
+        if (%str.(%i+3) == "="): stop
+        add (chr (((%indices.3 & 3) << 6) + %indices.4)) to %chars
+    
+    return (%chars joined)
-- 
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