thash method

Proof

Below is a script that reproduces what the thash method does. It can be used as a proof of concept and also to verify the correctness of the auditor.

#!/bin/bash
# This script simulates thash method with selectable hash algorithms.
#!/bin/bash
# This script simulates thash method with selectable hash algorithms.

if [ "$#" -ne 3 ]; then
    echo "Use: $0 file alg_hash blockSize"
    echo "Ex: $0 ./any_file sha256 10MB"
    echo "alg_hash can be: sha256, sha512, sha3-256, sha3-512, k12 or blake3 ."
    echo "blockSize is a number with KB, MB, GB or TB. Ex: 10MB, 5GB, etc"
    
    echo "alg_hash will use one of commands to hash: sha256sum, sha512sum, sha3sum, k12sum or b3sum . So, it needs to in the path !"
    echo "If the file is in current dir, use ./file"
    exit 1
fi

# Get arguments
file="$1"
alg_hash="$2"
block_str_auditor="$3"
block_str="${block_str_auditor::-1}"

last_char="${block_str_auditor: -1}"
if [[ "$last_char" != "B" ]]; then
    echo "Error: Last character must be 'B'" >&2
    exit 1
fi

unity="${block_str_auditor: -2:1}"

if [[ ! "$unity" =~ ^[KMGTPE]$ ]]; then
    echo "Error: Invalid unit '$unity'" >&2
    exit 1
fi

# Test if file exists
if [ ! -f "$file" ]; then
    echo "File '$file' not found."
    exit 1
fi

# Select hashing utility based on alg_hash
option_cmd=""
case "$alg_hash" in
    sha256)
        hash_cmd="sha256sum"
    ;;
    sha512)
        hash_cmd="sha512sum"
    ;;
    sha3-256)
        hash_cmd="sha3sum"
        option_cmd=" -a 256"
    ;;
    sha3-512)
        hash_cmd="sha3sum"
        option_cmd=" -a 512"
    ;;
    k12)
        hash_cmd="k12sum"
    ;;
    blake3)
        hash_cmd="b3sum"
    ;;
    *)
        echo "Invalid hash algorithm. Choose: sha256, sha512, sha3-256, sha3-512, k12, blake3."
        exit 1
    ;;
esac

if ! command -v "$hash_cmd" &> /dev/null; then
    echo "Error: $hash_cmd is not installed. Install it and try again."
    exit 1
fi
hash_cmd="$hash_cmd$option_cmd"

auditor_cmd="auditor"

if ! command -v "$auditor_cmd" &> /dev/null; then
    echo "Error: $auditor_cmd is not installed. Install it and try again."
    exit 1
fi

# Create dir, name files, clean eventual files
dir_name="${file}_dir_${block_str}_${alg_hash}"
file_chain_hash="${file}_${block_str}_chain.${alg_hash}.txt"
file_thash="${file}_${block_str}.${alg_hash}.thash.txt"
file_thash_auditor="${file}_${block_str}.${alg_hash}.thash.auditor.txt"
mkdir -p "$dir_name"
rm -f "$dir_name"/part_*

# Split file in blocks of blockSize
split -b "$block_str" "$file" "$dir_name"/part_

# Hash each split file and save the hash
for part_file in "$dir_name"/part_*; do
    
    $hash_cmd "$part_file" > "$part_file"."${alg_hash}".hash.txt
    
    # sha3sum prints c2a0 (in hex) after hash value. Need remove it, as well \n and spaces
    cat "$part_file"."${alg_hash}".hash.txt | awk '{gsub(/ *\*.*/, ""); print $1}' | cut -d " " -f 1 | tr -d '\n' | sed $'s/\xc2\xa0//g' > "$part_file"."${alg_hash}".txt
    
done

# Chain all hashes
cat "$dir_name"/*."${alg_hash}".txt > "$file_chain_hash"

# Hash the chain of hashes, cutting spaces and newline char
$hash_cmd "$file_chain_hash" | cut -d " " -f 1 | tr -d '\n' > "$file_thash"

# Print result
echo "${alg_hash}<THASH-${block_str_auditor}> with this script and ${hash_cmd}:"
cat "$file_thash"
echo ""

echo ""
echo "${alg_hash}<THASH-${block_str_auditor}> with auditor:"
auditor hash "$file" -a "$alg_hash" -b "$block_str_auditor" -l -q > "$file_thash_auditor" 2> /dev/null
cat "$file_thash_auditor"

echo ""
echo "normal hash with ${hash_cmd}"
$hash_cmd "$file"

echo ""
echo "normal hash with auditor "
auditor hash "$file" -d -a "$alg_hash" -q -l 2> /dev/null
echo ""
        

Here are the results of proof.sh applied to a random file: