#!/bin/bash
# packages: cracklib-runtime, openssh-client(s)
# set -x # debug mode
set -Eeuo pipefail # safety shit. fail to trap on any error, undeclared var, pipe filure
IFS=$'\n\t' # safer handlin of filenames and shit with spaces, prevents splitting
trap 'error_handler $?' ERR # prettyful trap for error handlin :3

# these can be adjusted interactively
default_email="anonymous@anonymous.com"
default_algo="ed25519"
default_working_dir="$PWD"
default_key_name="Signing_Key_$default_algo"
default_public_files_dir_name="public_files"
# set here not thrugh interactive
txt_help_file_name="How_to_Verify_Files.txt"
RED='\033[0;31m' # red color for errorz
NO_COLOR='\033[0m' # reset to no color after red

# my silly pretty lil error handler :3
error_handler() {
    local retcode="$1" # get dat retcode
    # color da error output red :3
    echo -e "\n\n${RED}ERROR: Failure With Return Code: $retcode on Line: $BASH_LINENO at Second: $SECONDS Timestamp: $(date)${NO_COLOR}"
    echo -e "${RED}Command:\n\t$BASH_COMMAND\n\n${NO_COLOR}"
}

### todo: environment check/package installa
### todo: make input of both passphrases only happen twice, compared against teach other, and tested
### todo: handle fix perms shit by narrowly changing perms of da private key fiel
### todo: handle file paths better
### todo: cleanup output
####    spacing
####    y better feedback for success/fail of shit
####    clean shit uuuup
### todo: allow file input from cli
### todo: cli options for generate/sign/verify/all
### todo: auto-compress pub files? (cleartext zip, encrypted 7z?)
### todo: maybe figure out how to unify these sigs and files and shit?

read -p "Enter path to file to sign: " file_to_sign
read -p "Enter Private 50+ Character Passphrase For Checksum Verification: " checksum_passphrase
read -p "Enter Checksum Verification Passphrase Again: " checksum_passphrase_check
checksum_passphrase_len=${#checksum_passphrase} # get length of provided checksum passphrase
# check for match
if [[ "$checksum_passphrase" == "$checksum_passphrase_check" ]]; then
    echo "OK: Checksum Verification Passphrases Match"
    # check length greateer than or equal to 50
    if [ $checksum_passphrase_len -ge 50 ]; then
        echo "OK: Checksum Verification Passphrase is greater or equal to 50 chars long"
        # check for pass security using cracklib-check from cracklib-runtime package
        cracklib_check=$(echo "$checksum_passphrase" | cracklib-check)
        if [[ ! "$cracklib_check" =~ OK$ ]]; then # check if it ends with anythign other than OK
            echo -e "\n\nFAIL: Checksum Verification Passphrase NOT Secure Enough!\nReported: $cracklib_check${NO_COLOR}\n\n"
            exit 1
        else
            echo "OK: Cracklib Reports Password is Secure"
        fi
    else
        echo -e "\n\n${RED}FAIL: Checksum Verification Passphrase NOT Longer Than the Minimum 50 Chars${NO_COLOR}\n\n"
        exit 1 
    fi
else
    echo -e "\n\n${RED}FAIL: Checksum Verification Passphrases DO NOT MATCH${NO_COLOR}\n\n"
    exit 1
fi
read -p "Enter working directory (empty for $default_working_dir): " working_dir
read -p "Enter email to use (empty for $default_email): " email
read -p "Enter public key comment (empty for $default_email): " comment
read -p "Enter algo (empty for $default_algo): " algo
read -p "Enter new key name (Empty for $default_key_name): " key_name ### todo: test/handle
read -p "Enter public files output dir name (Empty for $default_public_files_dir_name): " public_files_dir_name

# handle defaults
## handle default working dir
### todo: check for dir existance first
### todo: check for dir rw perms first
if [ -z "$working_dir" ]; then
    echo "Changing directory to $default_working_dir"
    working_dir="$default_working_dir"
    cd "$working_dir"
else
    echo "Changing directory to $working_dir"
    cd "$working_dir"
fi
## handle ddefault email
if [ -z "$email" ]; then
    email="$default_email"
fi
## handle ddefault pub key comment
### todo: handle empty comment?
if [ -z "$comment" ]; then
    comment="$default_email"
fi
## handle ddefault algo
### todo: check against ssh-keygen
if [ -z "$algo" ]; then
    algo="$default_algo"
fi
## handle default key name
if [ -z "$key_name" ]; then
    key_priv_path="$working_dir/$default_key_name"
else
    key_priv_path="$working_dir/$key_name"
fi
## handle default publid files dir name/path
if [ -z "$public_files_dir_name" ]; then
    public_files_dir_path="$working_dir/$default_public_files_dir_name"
else
    public_files_dir_path="$working_dir/$public_files_dir_name"
fi

# environment checks
## check if file exists and is regular file
## todo: make this use absolute paths
if [ ! -f "$file_to_sign" ]; then
    echo "FAIL! $file_to_sign not found or not regular file! Exititng!"
    exit 1
fi

# sum housekeeping, makin file pathssss and shit
sig_file_path="$file_to_sign.sig" # path to detached signature file
key_pub_path="$key_priv_path.pub" # path to pub key file
allowed_signers_path="$working_dir/allowed_signers" # path to allowed_signers file
file_to_sign_checksums_path="$file_to_sign.checksums" # checksums file
file_to_sign_checksums_sig_path="$file_to_sign_checksums_path.sig" # checksums file sig file 
file_to_sign_basename="$(basename $file_to_sign)" # file_to_sign name only
file_to_sign_contents="$(cat $file_to_sign)" # file_to_sign file contents

# generate key pair
## tell user to be sure to use a sdolid passphrase and wait for enter to continue
echo "BE SURE TO SAVE THIS KEY WITH A SINGLE USE DURABLE STRONG PASSPHRASE WHEB PROMPTED"
read -p "enter to continue" # wait for enter to contintue, nothign is read
echo "Generating new key pair $key_priv_path and $key_pub_path with algo $algo with comment/identity $email"
## -t is algo, -C is comment in pubkey -f is path to key file name
ssh-keygen -t "$algo" -C "$comment" -f "$key_priv_path"
## fix perms and pwnership on keyfilez
echo "Changing perms on dis dir and files to user/group $USER"
chown $USER:$USER -R "$working_dir"
find "$working_dir" -type d -exec chmod 700 {} \;
find "$working_dir" -type f -exec chmod 600 {} \;

# create a local allowed_signers file
echo "Creating alllowed_singers file at $allowed_signers_path with $key_pub_path and identity $email"
## format: <email> <pub key>
pub_key_text="$(cat $key_pub_path)" # text of public key
echo "$email $pub_key_text" > "$allowed_signers_path" # dont append, just one off here

# generate checksums
## normal ones sha256 and sha512
### initialize the checksums file new with normal sha256 and sha512 digests
echo -e "sha256 $(sha256sum $file_to_sign)\nsha512 $(sha512sum $file_to_sign)" > "$file_to_sign_checksums_path"
## salted hashes
### salted sha256
#### normal append first part of line
echo "sha256 (private salt+\`cat file\`): " >> "$file_to_sign_checksums_path"
#### no trailing newline echo to stdin sha256sum, clean up with awk, append to checksums file line
echo -n "${checksum_passphrase}${file_to_sign_contents}" | sha256sum | awk '{print $1}' >> "$file_to_sign_checksums_path"
#### no trailing newline echo append to checksums file, completing the sha256 salted line
echo -n "$file_to_sign_basename" >> "$file_to_sign_checksums_path"
### salted sha512
#### normal append first part of salted sha512 line
echo "sha512 (private salt+\`cat file\`): " >> "$file_to_sign_checksums_path"
#### no trailing newline echo to stdin sha512sum, clean up with awk, append to checksums file line
echo -n -e "${checksum_passphrase}${file_to_sign_contents}" | sha512sum | awk '{print $1}' >> "$file_to_sign_checksums_path"
#### no trailing newline echo append to checksums file, completing the sha512 salted line and completing the file
echo -n "$file_to_sign_basename" >> "$file_to_sign_checksums_path"

# sign the files
## sign da file to sign
echo "Signing $file_to_sign with detached signature file $sig_file_path"
### -Y mode (sign) -f private key path -n file (fuile mode) file.txt (file to sign)
ssh-keygen -Y sign -f "$key_priv_path" -n file "$file_to_sign"
## sign checksums file
echo "Signing $file_to_sign_checksums_path with detached signature file $file_to_sign_checksums_sig_path"
### -Y mode (sign) -f private key path -n file (fuile mode) file.txt (file to sign)
ssh-keygen -Y sign -f "$key_priv_path" -n file "$file_to_sign_checksums_path"

# verify sigs
## file to sign
echo "Verifying signature of $file_to_sign with signature file $sig_file_path for public key $key_pub_path and identitiy $email"
### -Y mode (verify) -f path to allowed_signers file -I email specified in allowed_signers file -n file (file mode) -s path to sig file < file.txt input file to verify
ssh-keygen -Y verify -f "$allowed_signers_path" -I "$email" -n file -s "$sig_file_path" < "$file_to_sign"
## checksums file
echo "Verifying signature of $file_to_sign_checksums_path with signature file $file_to_sign_checksums_sig_path for public key $key_pub_path and identitiy $email"
### -Y mode (verify) -f path to allowed_signers file -I email specified in allowed_signers file -n file (file mode) -s path to sig file < file.txt input file to verify
ssh-keygen -Y verify -f "$allowed_signers_path" -I "$email" -n file -s "$file_to_sign_checksums_sig_path" < "$file_to_sign_checksums_path"

# make public files copy
## create public files dir or fail if exists
### todo: use -p for ez reuse?
echo "Creating public files output dir at $public_files_dir_path"
mkdir "$public_files_dir_path"
## copy the pub files there
echo "Copying publc key, local allowed_signatures file, signed file, detached signature file, checksums file, and detached checksums signature file to $public_files_dir_path"
cp "$key_pub_path" "$public_files_dir_path" # public key
cp "$allowed_signers_path" "$public_files_dir_path" # allowed signers file
cp "$file_to_sign" "$public_files_dir_path" # signed file
cp "$sig_file_path" "$public_files_dir_path" # main file sig file
cp "$file_to_sign_checksums_path" "$public_files_dir_path" # checksums file
cp "$file_to_sign_checksums_sig_path" "$public_files_dir_path" # checksums sig file
## generate the help txt file and put it in place
### get filenames only from the paths via basename
allowed_signers_path_basename="$(basename $allowed_signers_path)"
sig_file_path_basename="$(basename $sig_file_path)"
checksums_sig_file_basename="$(basename $file_to_sign_checksums_sig_path)"
checksums_file_basename="$(basename $file_to_sign_checksums_path)"
### format help text
help_txt="To Verify Signatures: (Linux)\n\tssh-keygen -Y verify -f \"$allowed_signers_path_basename\" -I \"$email\" -n file -s \"$sig_file_path_basename\" < \"$file_to_sign_basename\"\n\tssh-keygen -Y verify -f \"$allowed_signers_path_basename\" -I \"$email\" -n file -s \"$checksums_sig_file_basename\" < \"$checksums_file_basename\"\n\nTo Verify Normal Checksums (Linux):\n\tsha256sum $file_to_sign_basename\n\tsha256sum $file_to_sign_basename\n\t\tThen compare to values in $checksums_file_basename\n\nTo Verify Authenticated Checksums Via Private Salt (Linux):\n\tprivate_salt="\<PROVIDED SALT HERE\>"\n\techo -n -e \"\${private_salt}\$(cat $file_to_sign_basename)\" | sha256sum\n\techo -n -e \"\${private_salt}\$(cat $file_to_sign_basename)\" | sha512sum\n\t\tThen compare to values in $checksums_file_basename\n"
### maek da file
echo "Creating custom help txt file in $public_files_dir_path/$txt_help_file_name"
echo -e "$help_txt" > "$public_files_dir_path/$txt_help_file_name"

# declare victory :3
echo -e "\nall donesies :3\n"