btsync-secret

#!/bin/sh
#/ Usage: btsync-secret [option]...
#/ A Bittorrent Sync Secret Generator
set -e

h_flag=false
v_flag=false
e_flag=false
n_flag=false
c_flag=false
rod59_secret=""
secret_length=""
rand_binary=""
new_secret=""

function show_help() {
    echo -e "\nbtsync-secret, a Bittorrent Sync Secret Generator"
    echo "Usage: btsync-secret [option]..."
    echo -e "\nRun btsync-secret without flags to generate a standard read-write secret.\n(33 character base32)"
    echo -e "\nOptions:"
    echo -e "  -h\tShow this help."
    echo -e "  -v\tShow details as secrets are being generated."
    echo -e "  -e\tGenerate a read-write-encrypted secret.\n\t(33 character base32 with encrypted peer support)\n\t  Similar to a standard read-write secret, except Bittorrent\n\t  Sync calculates an encrypted hash tree for the folder. All\n\t  files are encrypted before being synced to other peers."
    echo -e "\n  -n\tGenerate a 33 character read-only-encrypted secret from a 59\n\tcharacter read-only-decrypted secret.\n\t  A 59 character read-only-decrypted secret decrypts files\n\t  synced from an encrypted peer, and stores those files\n\t  decrypted on the peer.\n\t  A 33 character read-only-encrypted secret cannot decrypt files\n\t  synced from an encrypted peer, and stores those files\n\t  encrypted on the peer."
    echo -e "\n  -c\tGenerate a custom base64 secret. Default length is 40 characters.\n\t  For custom length, enter a number over 40. btsync-secret\n\t  generates a custom length rounded down from your chosen\n\t  number to the nearest number divisible by 4.\n"
}

while :
do
    case $1 in
        -h | --help | -\?)
            show_help
            exit 0
            ;;
        -v )
            v_flag=true
            shift
            ;;
        -e )
            e_flag=true
            shift
            test "$2" = "-v" && {
                v_flag=true
            }
            ;;
        -n )
            n_flag=true
            shift
            rod59_secret="$1"
            test "$1" = "-v" && {
                v_flag=true
                rod59_secret="$2"
            }
            test "$2" = "-v" && {
                v_flag=true
                rod59_secret="$1"
            }
            break
            ;;
        -c )
            c_flag=true
            shift
            secret_length="$1"
            test "$1" = "-v" && {
                v_flag=true
                secret_length="$2"
            }
            test "$2" = "-v" && {
                v_flag=true
                secret_length="$1"
            }
            break
            ;;
        --) # End of all options
            shift
            break
            ;;
        *[!-hvenc]*)
            printf >&2 'WARN: Unknown option (ignored): %s\n' "$1"
            exit 1
            ;;
        -*)
            printf >&2 'WARN: Unknown option (ignored): %s\n' "$1"
            exit 1
            ;;
        *)  # no more options. Stop while loop
            break
            ;;
    esac
done

function gen_base32_secret() {
    rand_binary=`head -c20 /dev/random`
    new_secret=`python -c "import base64; print base64.b32encode('''$rand_binary''')"`
    case "$new_secret" in
        *=*) gen_base32_secret ;;
    esac
}

function gen_base64_secret() {
    head -c$(($secret_length/4*3)) /dev/random | base64 -w0
}

function gen_roe33_secret {
    echo -n "F"
    echo -n "$rod59_secret" | head -c33 | cut -c2-
}

test ! "$h_flag" = true && test ! "$e_flag" = true && test ! "$n_flag" = true && test ! "$c_flag" = true && {
    test "$v_flag" = true && {
        test -n "$1" && {
            echo -e "\nYour input of \"$1\" was ignored.\nUse the -c flag to generate a secret of custom length."
        }
        echo -e "\nGenerating a standard read-write secret...\n(33 character base32)\n"
    }
    gen_base32_secret
    echo -e "A$new_secret"
    test "$v_flag" = true && {
        echo " "
    }
    exit 0
}

test "$h_flag" = true && test ! "$e_flag" = true && test ! "$n_flag" = true && test ! "$c_flag" = true && {
    show_help
    exit 0
}

test ! "$h_flag" = true && test "$e_flag" = true && test ! "$n_flag" = true && test ! "$c_flag" = true && {
    test "$v_flag" = true && {
        test -n "$1" && {
            echo -e "\nYour input of \"$1\" was ignored.\nUse the -c flag to generate a secret of custom length."
        }
        echo -e "\nGenerating a read-write-encrypted secret...\n(33 character base32 with encrypted peer support)\n"
    }
    gen_base32_secret
    echo -e "D$new_secret"
    test "$v_flag" = true && {
        echo " "
    }
    exit 0
}

test ! "$h_flag" = true && test ! "$e_flag" = true && test "$n_flag" = true && test ! "$c_flag" = true && {
    test -z "$rod59_secret" && {
        test "$v_flag" = true && {
                echo -e "\nEnter a 59 character read-only-decrypted secret to\ngenerate a 33 character read-only-encrypted secret.\n"
            exit 0
        }
        exit 0
    }
    test -n "$rod59_secret" && {
        is_rod59_secret=`echo -n "$rod59_secret" | wc -m`
        test "$is_rod59_secret" = "59" && {
            test "$v_flag" = true && {
                echo -e "\nGenerating a read-only-encrypted secret...\n(33 character base32)\n"
            }
            gen_roe33_secret
            test "$v_flag" = true && {
                echo " "
            }
            exit 0
        }
        echo -e "\nEnter a 59 character read-only-decrypted secret to\ngenerate a 33 character read-only-encrypted secret.\n"
        exit 0
    }
}

test ! "$h_flag" = true && test ! "$e_flag" = true && test ! "$n_flag" = true && test "$c_flag" = true && {
    test -z "$secret_length" && {
        test "$v_flag" = true && {
            echo -e "\nGenerating a custom read-write secret...\n(40 character base64)\n"
        }
        secret_length=40
        gen_base64_secret
        test "$v_flag" = true && {
            echo -e "\n"
            exit 0
        }
        echo
        exit 0
    }
    test -n "$secret_length" && {
        case $secret_length in
            ''|*[!0-9]*)
                echo -e "\nFor a secret of custom length, enter a number over 40\n"
                exit 0
            ;;
            *)
                test "$secret_length" -ge 40 && {
                    test "$v_flag" = true && {
                        echo -e "\nGenerating a custom length read-write secret...\n("$((($secret_length/4)*4))" character base64)\n"
                    }
                    gen_base64_secret
                    test "$v_flag" = true && {
                        echo -e "\n"
                        exit 0
                    }
                    echo
                    exit 0
                }
                echo -e "\nFor a secret of custom length, enter a number over 40\n"
                exit 0
            ;;
        esac
    }
}