Stegsnow, commonly known as ‘snow’, is a lightweight command-line steganography tool that hides messages within the whitespace of text files. By embedding data in trailing spaces and tabs, it creates seemingly innocent text files that contain hidden information. This approach is particularly effective for hiding information in emails, source code comments, and text documents where whitespace changes are typically invisible.
- Text-based hiding: No dependency on image or audio files
- Whitespace encoding: Uses spaces and tabs as steganographic channel
- Low overhead: Minimal file size increase
- Plain text distribution: Compatible with email, forums, chat
- Simple encryption: Basic password protection available
- Command-line: Scriptable and automatable
- Lightweight: Minimal system requirements
# Install from package manager (Debian/Ubuntu)
sudo apt-get update
sudo apt-get install snow
# Or compile from source
wget http://www.darkside.com.au/snow/snow-20130616.tar.gz
tar xzf snow-20130616.tar.gz
cd snow-20130616
gcc -o snow snow.c
sudo mv snow /usr/local/bin/
# Using Homebrew
brew install snow
# Or manual compilation
# Download source from darkside.com.au
gcc -o snow snow.c
mv snow /usr/local/bin/
# Using MinGW or Cygwin compiler
# Download source: snow-20130616.tar.gz
# Extract and compile
gcc -o snow.exe snow.c
# Or download pre-compiled binary
# Add to PATH for command-line access
# Check installation
snow -h
# Expected output
# Snow v1.1 (c) 1998 Mark Cooke
# Usage: snow [ -S | -C ] [ -p passwd ] [ -m message ] infile outfile
| Method | Character | Binary | Use Case |
|---|
| Space | ASCII 32 | Represents 0 | Common, hard to detect |
| Tab | ASCII 9 | Represents 1 | Less common, visible in editors |
| Combined | Space + Tab | Variable | Maximum capacity |
Text file: "The quick brown fox"
+ 8 bits of data encoded in trailing whitespace
= Still appears as: "The quick brown fox"
(whitespace invisible in most viewers)
| Method | Capacity | Detectability | Distribution |
|---|
| Whitespace | Low (bits/KB) | Very low | High (text format) |
| Image LSB | High (100s KB) | Medium | Medium (image files) |
| Linguistic | Low (bits/word) | Very low | High (text format) |
| Format | Medium | Low | Medium (varies) |
# Simple hiding (no encryption)
snow -S -m "Secret message here" input.txt output.txt
# Explanation:
# -S = hide message (Stegano mode)
# -m = message to hide
# input.txt = cover text file
# output.txt = stego text file (with hidden message)
# Extract hidden message (no encryption)
snow -C output.txt
# Explanation:
# -C = extract/Check mode
# output.txt = stego file to analyze
# Result: Prints hidden message to stdout
# Hide with encryption
snow -S -p "MyPassword123!" -m "Confidential data" cover.txt stego.txt
# Extract with password
snow -C -p "MyPassword123!" stego.txt
# If password matches → hidden message displayed
# If password wrong → random garbage output
# Step 1: Create cover message
cat > email_body.txt << 'EOF'
Hi Sarah,
Thanks for the update on the project. The timeline looks good.
Let me know if you need any additional resources.
Best regards,
John
EOF
# Step 2: Hide secret instruction
snow -S -p "SecureKey2024" \
-m "Meeting moved to 3PM Tuesday in Room 405" \
email_body.txt email_stego.txt
# Step 3: Send stego text via email
cat email_stego.txt | mail -s "Project Status" recipient@example.com
# Recipient:
# Reads normal email message
# Uses: snow -C -p "SecureKey2024" email_stego.txt
# Receives hidden message
# Step 1: Create source code cover file
cat > comment_cover.cpp << 'EOF'
// Important constants for the algorithm
// Maximum iteration count for convergence testing
int MAX_ITERATIONS = 10000;
// Threshold value for acceptable error margin
double ERROR_THRESHOLD = 0.00001;
EOF
# Step 2: Embed credentials in whitespace
snow -S -p "CodeSecret" \
-m "api_key=sk-abc123def456ghi789jkl" \
comment_cover.cpp comment_stego.cpp
# Step 3: Use in project (looks normal in IDE)
# Colleague extracts: snow -C -p "CodeSecret" comment_stego.cpp
# Step 1: Create document
cat > document.txt << 'EOF'
This is an important document requiring authentication.
The contents have been verified and approved.
EOF
# Step 2: Hide approval signature
TIMESTAMP=$(date +%s)
SIGNATURE="Approved by Admin on $TIMESTAMP SHA256:abc123..."
snow -S -p "AdminPassword" \
-m "$SIGNATURE" \
document.txt document_signed.txt
# Step 3: Verify authenticity
# Recipient verifies: snow -C -p "AdminPassword" document_signed.txt
# Compares signature with known database
#!/bin/bash
# File: hide_batch.sh
# Batch hide messages in multiple text files
INPUT_DIR="./documents"
OUTPUT_DIR="./stego_documents"
PASSWORD="$1"
MESSAGE="$2"
mkdir -p "$OUTPUT_DIR"
for file in "$INPUT_DIR"/*.txt; do
filename=$(basename "$file")
output="$OUTPUT_DIR/$filename"
echo "Processing: $filename"
snow -S -p "$PASSWORD" -m "$MESSAGE" "$file" "$output"
if [ $? -eq 0 ]; then
echo "✓ Success: $filename"
else
echo "✗ Failed: $filename"
fi
done
echo "Batch processing complete"
#!/bin/bash
# Hide message in layers for extra security
PLAINTEXT="Secret message"
PASSWORD1="Layer1Pass"
PASSWORD2="Layer2Pass"
# Layer 1: Hide in cover text 1
snow -S -p "$PASSWORD1" -m "$PLAINTEXT" cover1.txt temp1.txt
# Layer 2: Use layer 1 output as input for layer 2
# Embed different data in layer 1 stego text
snow -S -p "$PASSWORD2" -m "Additional data" temp1.txt final.txt
# Extraction requires reverse process:
# snow -C -p "$PASSWORD2" final.txt → recover temp1.txt contents
# snow -C -p "$PASSWORD1" temp1.txt → recover original message
# Text file analysis for hiding capacity
# Example: 10KB text file (approximately 10,000 bytes)
# Realistic capacity: 1-2 bits per 10-20 trailing characters
# Minimum of 1 character per 8 bits of data
CHARS_NEEDED=$((MESSAGE_BITS / 8 + (MESSAGE_BITS % 8 > 0 ? 1 : 0)))
# Safe estimation:
# 100 lines × 80 characters = 8,000 chars
# Can hide: ~8,000 bits = ~1,000 bytes = ~1KB safely
# Use larger source documents for larger messages
✓ Invisibility: Whitespace undetectable in most contexts
✓ Portability: Text files transmit everywhere
✓ Simplicity: Easy to understand and implement
✓ Deniability: Legitimate text with hidden content
✓ Robustness: Whitespace survives many transformations
✗ Limited capacity: Only hundreds of bytes realistically
✗ Statistical analysis: Unusual spacing patterns detected
✗ Tool knowledge: Anyone with snow tool can extract
✗ Preprocessing: Line reflow/reformatting destroys data
✗ Weak encryption: Basic password, no strong cipher
| Technique | Detection | Mitigation |
|---|
| Whitespace analysis | Check trailing spaces | Randomize dummy spaces |
| Entropy analysis | Statistical patterns | Mix legitimate and stego |
| Format conversion | Text to PDF destroys data | Careful distribution |
| Hex dump inspection | See trailing bytes | Use visual tools only |
# Method 1: Add decoy whitespace
cat >> cover.txt << 'EOF'
This is normal text.
With trailing spaces.
Looks ordinary.
EOF
# Method 2: Hide in long lines
# Legitimate text with extensive explanation spanning multiple lines
# naturally has trailing spaces in word-wrapped formats
# Method 3: Multiple small messages
# Instead of one 500-byte message
# Hide five 100-byte messages in different files
# Distribute across documents
# Method 4: Strong password discipline
snow -S -p "MyP@ssw0rd!Complex#2024" -m "secret" cover.txt stego.txt
# NEVER: -p "password" or -p "123456"
# Create FAQ that contains secret instructions
cat > faq_cover.txt << 'EOF'
Frequently Asked Questions
Q: How do I reset my password?
A: Click forgot password and follow the email instructions.
Q: What is the refund policy?
A: Standard 30-day money-back guarantee applies.
Q: How do I contact support?
A: Email support@company.com or use contact form.
EOF
# Hide coordinator meeting details
snow -S -p "CoordKey" \
-m "Meeting 5PM Tuesday Zoom: zoom.us/j/123456789 Pass: abcd1234" \
faq_cover.txt faq_stego.txt
# Legitimate looking FAQ document contains hidden meeting info
# Only authorized users with password can extract
# Security researcher finds vulnerability
# Responsible disclosure requires non-public communication
# Create public document with stego communication
cat > security_advisory.txt << 'EOF'
Security Advisory Template
Vulnerability Type: [Category]
Severity: [Level]
Affected Systems: [List]
Description: [Details]
Mitigation: [Steps]
EOF
# Hide non-public vulnerability details
VULN_DETAILS="CVE-2024-12345: Buffer overflow in component X, EIP overwrite at offset 524"
snow -S -p "VendorSecret" -m "$VULN_DETAILS" \
security_advisory.txt security_advisory_stego.txt
# Public sees template
# Vendor receives stego file, extracts with private password
# Gets detailed vulnerability information privately
# Basic syntax
snow [mode] [options] infile outfile
# Modes
-S # Stegano mode (hide message)
-C # Check mode (extract message)
# Options
-p password # Password protection
-m "message" # Message to hide
-h # Display help
# Hide with all options
snow -S -p "SecurePass123" -m "Classified data here" \
cover_document.txt secret_output.txt
# Extract with password
snow -C -p "SecurePass123" secret_output.txt
# Hide without password (basic)
snow -S -m "Hello World" input.txt output.txt
# Extract without password
snow -C output.txt
# Extract and save to file
snow -C stego.txt > extracted_message.txt
# Check file without extraction
snow -C stego.txt | head -n 1
#!/bin/bash
# Extract from multiple stego files
PASSWORD="$1"
STEGO_DIR="./stego_files"
OUTPUT_DIR="./extracted"
mkdir -p "$OUTPUT_DIR"
for stego_file in "$STEGO_DIR"/*.txt; do
basename=$(basename "$stego_file" .txt)
output_file="$OUTPUT_DIR/${basename}_extracted.txt"
echo "Extracting: $stego_file"
snow -C -p "$PASSWORD" "$stego_file" > "$output_file"
if [ -s "$output_file" ]; then
echo "✓ Extracted to: $output_file"
else
echo "✗ Extraction failed"
rm "$output_file"
fi
done
#!/bin/bash
# Multi-layer security: whitespace stego + GPG encryption
MESSAGE="$1"
GPG_RECIPIENT="$2"
COVER_FILE="$3"
OUTPUT_FILE="$4"
# Step 1: Encrypt message with GPG
ENCRYPTED=$(echo "$MESSAGE" | gpg --armor --recipient "$GPG_RECIPIENT" -c)
# Step 2: Hide encrypted message in whitespace
snow -S -m "$ENCRYPTED" "$COVER_FILE" "$OUTPUT_FILE"
echo "Message encrypted with GPG and hidden with snow"
echo "Output: $OUTPUT_FILE"
# Recovery:
# Step 1: Extract from stego: snow -C output_file
# Step 2: Decrypt with GPG: echo "encrypted_text" | gpg -d
Cover file sizes and realistic capacity:
10 KB file → ~100-200 bytes safe capacity
50 KB file → ~500-1000 bytes safe capacity
100 KB file → ~1000-2000 bytes safe capacity
500 KB file → ~5000-10000 bytes safe capacity
Note: Capacity varies with text density and structure
| Issue | Impact | Solution |
|---|
| HTML cleaning | Strips whitespace | Use plain text only |
| Word processors | Reformats text | Export as plain text |
| Email clients | Trailing space removal | Use secure channels |
| Version control | Normalizes whitespace | Don’t use in repos |
# Current password implementation
# ⚠️ NOT cryptographically strong
# Uses basic algorithm, vulnerable to brute force
# RECOMMENDATION: Add GPG encryption layer
# Don't rely on snow password alone for sensitive data
# Instead: GPG encrypt message → Hide encrypted data with snow
# 1. Use strong passwords (minimum 16 chars if using snow encryption)
PASSWORD="MyComplex!Pass@2024#Secure"
# 2. Verify before distribution
snow -C -p "$PASSWORD" test_stego.txt
# 3. Secure cover text source
# Use publicly available documents, not custom-created
# Avoid suspiciously large files
# 4. Varied document types
# Don't always use same source documents
# Mix emails, documents, code comments
# 5. Minimize traffic pattern
# Don't hide messages too frequently
# Vary timing of distribution
# 6. Secure password transmission
# Share password via separate secure channel
# Never transmit password with stego file
GOOD cover documents:
- Public documents (Wikipedia excerpts)
- FAQ pages
- Email chains
- Source code comments
- Documentation
POOR cover documents:
- Custom-created documents
- Unusually long text files
- Documents with suspicious structure
- Newly created files
| Problem | Cause | Solution |
|---|
| ”snow: command not found” | Not installed or not in PATH | Run which snow or reinstall |
| Extraction returns garbage | Wrong password | Verify correct password |
| No output on extraction | File corrupted/not stego | Verify with snow -C file.txt |
| Message garbled | Binary message in text format | Encode binary as base64 first |
# Check file type and size
file stego.txt
ls -lh stego.txt
# View hex dump to see whitespace
hexdump -C stego.txt | tail -n 20
# Search for embedded data patterns
od -c stego.txt | grep " "
# Count trailing spaces per line
awk '{print gsub(/ $/,"")}' stego.txt
| Tool | Method | Capacity | Ease |
|---|
| Snow | Whitespace | Very low | Very high |
| Steghide | DCT (audio/JPEG) | Medium | Medium |
| LSB Hide | Image LSB | High | Medium |
| SilentEye | Visual | High | High |
- Research: Steganography analysis
- Secure communication: Authorized team channels
- Privacy: Personal data protection
- Responsible disclosure: Vendor communication
- Malware distribution
- Unauthorized surveillance
- Evasion of security monitoring
- Copyright violation distribution
Snow provides a lightweight, effective method for hiding information in plain text through whitespace encoding. Its primary strengths are invisibility and ease of distribution, while limitations include low capacity and weak encryption. Best used as one layer in a multi-layered security approach, combined with strong encryption algorithms like GPG for sensitive data protection.
