initial commit (b32, sha1, hmac)

src/base.typ

@@ -0,0 +1,62 @@
+#import "utils.typ": z-fill, bin-to-int
+#let b32-alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
+
+/// Decodes a base32-encoded value
+/// #test(
+///   `jumble.b32-decode("LFHVKUCJ") == bytes("YOUPI")`
+/// )
+/// ```example
+/// #str(b32-decode("LFHVKUCJ"))
+/// ```
+/// -> bytes
+#let b32-decode(
+  /// -> str
+  encoded
+) = {
+  let decoded-bin = ()
+  for char in encoded {
+    if char == "=" {
+      break
+    }
+    let i = b32-alphabet.position(char)
+    decoded-bin += z-fill(str(i, base: 2), 5).clusters().map(int)
+  }
+  decoded-bin = decoded-bin.slice(
+    0,
+    calc.div-euclid(decoded-bin.len(), 8) * 8
+  )
+  let decoded-bytes = decoded-bin.chunks(8).map(bin-to-int)
+  return bytes(decoded-bytes)
+}
+
+/// Encodes a value in base32
+/// #test(
+///   `jumble.b32-encode(bytes("YOUPI")) == "LFHVKUCJ"`
+/// )
+/// ```example
+/// #b32-encode(bytes("YOUPI"))
+/// ```
+/// -> str
+#let b32-encode(
+  /// -> bytes
+  decoded
+) = {
+  let encoded = ""
+  let decoded-bin = array(decoded).map(b => z-fill(str(b, base: 2), 8)).join()
+  decoded-bin = decoded-bin.clusters().map(int)
+  let groups = decoded-bin.chunks(40)
+  for group in groups {
+    let chars = group.chunks(5)
+    if chars.last().len() != 5 {
+      chars.last() += (0,) * (5 - chars.last().len())
+    }
+    let chars = chars.map(bin-to-int)
+                     .map(c => b32-alphabet.at(c))
+    encoded += chars.join()
+    let pad = 8 - chars.len()
+    if pad != 0 {
+      encoded += "=" * pad
+    }
+  }
+  return encoded
+}