feat(user/rsync_tranches):Make more granular

[BK-2020-03.git] / user / bknpass

diff --git a/user/bknpass b/user/bknpass
index 4f53da0fa3d0d1035c0153abf0926f4bb7d47f7b..c1c1d1a34e657b75de46a83e7b57f329e9f2dde3 100755 (executable)
--- a/user/bknpass
+++ b/user/bknpass
@@ -1,14 +1,12 @@
 #!/bin/bash
 
-# Date: 2020-01-20T16:34Z
-#
 # Author: Steven Baltakatei Sandoval (baltakatei.com)
 #
 # License: This bash script, `bknpass`, is licensed under GPLv3 or
 # later by Steven Baltakatei Sandoval:
 #
 #    `bknpass`, an alphanumeric password generator
-#    Copyright (C) 2020  Steven Baltakatei Sandoval (baltakatei.com)
+#    Copyright (C) 2021  Steven Baltakatei Sandoval (baltakatei.com)
 #
 #    This program is free software: you can redistribute it and/or modify
 #    it under the terms of the GNU General Public License as published by
@@ -34,8 +32,8 @@
 #   - Check if user-provided string is an integer using `bash` regular
 #     expression test.
 #
-#   - Calculate the minimum number of alphanumeric characters required
-#     to encode the specified number of bits of entropy.
+#   - Calculate the minimum number of bech32 base32 characters
+#     required to encode the specified number of bits of entropy.
 #
 #       - This step uses `bc` to calculate a logarithm float string
 #         and `awk` to convert the float into an integer, rounding up.
@@ -47,6 +45,10 @@
 #   - Use `echo` to display the passphrase in stdout with a trailing
 #     newline.
 #
+# Usage: bknpass [int]
+#
+# Example: bknpass 256
+#
 # Dependencies: bash, echo, bc, awk, tr, head. See end of file
 #
 # Tested on:
@@ -56,7 +58,7 @@
 
 #==Initialization==
 
-let ALPHABET_SIZE="26+26+10" # number of unique chars in [:alnum:], argument fed to `tr -c` in 'Generate passphrase' step)
+let ALPHABET_SIZE="32" # number of unique chars in bech32 base32 charset
 LOG_BASE=2 # Set logarithm base to 2
 
 # Define `echoerr` function which outputs text to stderr
@@ -65,17 +67,18 @@ function echoerr {
     echo "$@" 1>&2;
 }
 
-# Define `rpass` function which generates an alphanumeric passphrase of length $1 (ex: `rpass 22` generates a 22-char string)
-    # Note: function adapted from https://www.thegeekstuff.com/2010/04/unix-bash-function-examples/
+# Define `rpass` function which generates a base32 passphrase of length $1 (ex: `rpass 20` generates a 20-char string)
+#   Note: function adapted from https://www.thegeekstuff.com/2010/04/unix-bash-function-examples/
+#   Note: base32 charset uses bech32 charset
 function rpass {
-    cat /dev/urandom | LC_ALL=C tr -cd "[:alnum:]" | head -c ${1:-22}
+    cat /dev/urandom | LC_ALL=C tr -cd "qpzry9x8gf2tvdw0s3jn54khce6mua7l" | head -c ${1:-22}
 }
 
 
 #==Main Program==
 
 # Define $ENTROPY_BIT_COUNT1 as argument $1 or prompt user if $1 is not defined.
-    # note: argument test adapted from https://stackoverflow.com/a/6482403
+#     Note: argument test adapted from https://stackoverflow.com/a/6482403
 if [ -z "$1" ]
 then
     echo "Entropy bit count argument (\$1) not supplied."
@@ -87,23 +90,24 @@ else
 fi
 
 # Check if $ENTROPY_BIT_COUNT1 is an non-negative integer
-    # Note: Regular expression test is adapted from https://stackoverflow.com/a/806923
+#     Note: Regular expression test is adapted from https://stackoverflow.com/a/806923
 RETEST1='^[0-9]+$'
 if ! [[ $ENTROPY_BIT_COUNT1 =~ $RETEST1 ]] ; then
    echo "error: Not an integer." >&2; exit 1    
 fi
 
 # Calculate minimum count of chars needed to encode $ENTROPY_BIT_COUNT1 with alphabet size of $ALPHABET_SIZE as float
-    # Solve ln(a^n)/ln(2)=b for n using `bc` where
-      # a=$ALPHABET_SIZE
-      # n=$CHAR_COUNT1_FLOAT
-      # b=$ENTROPY_BIT_COUNT1
-    # Note: `bc` logarithm usage adapted from http://phodd.net/gnu-bc/bcfaq.html#bashlog
+#     Solve ln(a^n)/ln(2)=b for n using `bc` where
+#       a=$ALPHABET_SIZE
+#       n=$CHAR_COUNT1_FLOAT
+#       b=$ENTROPY_BIT_COUNT1
+#     Note: `bc` logarithm usage adapted from http://phodd.net/gnu-bc/bcfaq.html#bashlog
 CHAR_COUNT1_FLOAT=$(echo "$ENTROPY_BIT_COUNT1*l($LOG_BASE)/l($ALPHABET_SIZE)" | bc -l)
-    # Note: Float will be of form "21.49744370650136860806". This particular float should be rounded to "22" later.
+#     Note: Float will be of form "21.49744370650136860806".
+#     Note: This particular example float should be rounded to "22" later.
 
 # Round $CHAR_COUNT1_FLOAT1 up to next highest integer for use as argument in later bash functions.
-    # Note: awk expression from https://bits.mdminhazulhaque.io/linux/round-number-in-bash-script.html
+#     Note: awk expression from https://bits.mdminhazulhaque.io/linux/round-number-in-bash-script.html
 CHAR_COUNT1=$(echo "$CHAR_COUNT1_FLOAT" | awk '{print ($0-int($0)>0)?int($0)+1:int($0)}') 
 
 # Generate passphrase
@@ -148,6 +152,13 @@ echo -e "$PASS1"
 #   Date: 2010-04-21
 #   Date Accessed: 2020-01-20
 #
+# - Bech32 base32 charset
+#   https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki
+#   Author: Pieter Wuille <pieter.wuille@gmail.com>
+#   Date: 2017-03-20
+#   License: BSD-2-Clause
+#   Date: Accessed: 2021-01-23
+#
 # - Dependencies: bash, echo, bc, awk, tr, head.
 #
 #     - GNU bash, version 5.0.3(1)-release (x86_64-pc-linux-gnu)