first draft at bech32

Author: Lucien Grondin

bech32.sh

@@ -0,0 +1,81 @@
+# BECH32
+# see https://en.bitcoin.it/wiki/BIP_0173
+declare -a bech32=(
+  q p z r y 9 x 8
+  g f 2 t v d w 0
+  s 3 j n 5 4 k h
+  c e 6 m u a 7 l
+)
+declare -A bech32A
+for i in {0..31}
+do bech32A[${bech32[$i]}]=$i
+done
+
+bech32_polymod() {
+  declare -ia GEN=(0x3b6a57b2 0x26508e6d 0x1ea119fa 0x3d4233dd 0x2a1462b3)
+  declare -i  chk=1 b i v
+  for v
+  do
+    b=$((chk >> 25))
+    chk=$(( (chk & 0x1ffffff) << 5^v ))
+    for i in {0..4}
+    do ((chk^= (b >> i) & 1 ? GEN[i] : 0))
+    done
+  done
+  echo $chk
+}
+ord() { LC_CTYPE=C printf '%d' "'$1"; }
+bech32_hrp_expand() {
+  declare -i x
+  for x
+  do echo $(( $x >> 5 ))
+  done
+  echo 0
+  for x
+  do echo $(( $x & 31 ))
+  done
+}
+bech32_verify_checksum() {
+  mapfile -t hrp  < <(echo -n "${1%1*}"  |grep -o . |while read c; do ord $c; echo; done)
+  mapfile -t data < <(echo -n "${1##*1}"|grep -o . |while read c; do echo ${bech32A[$c]}; done)
+
+  test $(
+    bech32_polymod $(
+      bech32_hrp_expand "${hrp[@]}"
+      for x in "${data[@]}"
+      do echo $x
+      done
+    )
+  ) -eq 1
+}
+bech32_create_checksum() {
+  mapfile -t hrp  < <(echo -n "${1%1*}"  |grep -o . |while read c; do ord $c; echo; done)
+  mapfile -t data < <(echo -n "${1##*1}"|grep -o . |while read c; do echo ${bech32A[$c]}; done)
+  declare -i polymod=$(( $(bech32_polymod $(bech32_hrp_expand ${hrp[@]}) ${data[@]} 0 0 0 0 0 0) ^ 1))
+  declare -a checksum
+  for i in {0..5}
+  do checksum[$i]=$(( (polymod >> 5 * (5 - i)) & 31 ))
+  done
+  for c in ${hrp[@]}
+  do printf "\x$(printf "%x" $c)"
+  done
+  echo -n 1
+  for c in ${data[@]} ${checksum[@]}
+  do echo -n ${bech32[$c]}
+  done
+  echo
+}
+
+declare -a valid_checksum=(
+  a12uel5l
+  an83characterlonghumanreadablepartthatcontainsthenumber1andtheexcludedcharactersbio1tt5tgs
+  abcdef1qpzry9x8gf2tvdw0s3jn54khce6mua7lmqqqxw
+  11qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqc8247j
+  split1checkupstagehandshakeupstreamerranterredcaperred2y9e3w
+)
+
+for t in "${valid_checksum[@]}"
+do bech32_verify_checksum $t || echo wrong checksum
+done
+
+bech32_verify_checksum $(bech32_create_checksum foo1zzzzzzzzzz)