Random 20 char alphanumeric

openssl rand -hex 20

Using /dev/urandom

tr -dc 'A-Za-z0-9' </dev/urandom | head -c 20

Using pwgen (if installed)

pwgen 16 1


### Secure Password with Special Chars
```bash
# Include special characters
tr -dc 'A-Za-z0-9!@#$%^&*' </dev/urandom | head -c 20

# More secure version
openssl rand -base64 32 | tr -dc 'A-Za-z0-9!@#$%^&*' | head -c 24

Memorable Passwords

# Diceware-style (using wordlist)
shuf -n 4 /usr/share/dict/words | tr '\n' '-'

# Using apg (if installed)
apg -a 1 -M Ncl

API Keys & Tokens

UUID Generation

# UUID v4
uuidgen

# Or using Python
python3 -c "import uuid; print(uuid.uuid4())"

# Or using node
node -e "console.log(require('crypto').randomUUID())"

JWT-Style Tokens

# Random token (base64)
openssl rand -base64 32

# Hex token
openssl rand -hex 32

OAuth Secrets

# Client secret
openssl rand -base64 32

# 256-bit key
openssl rand -hex 32

Cryptographic Functions

Hash Password

# SHA-256 hash
echo -n "password" | openssl dgst -sha256

# SHA-512 hash
echo -n "password" | openssl dgst -sha512

# Bcrypt (using htpasswd)
htpasswd -nbBC 10 user password

Generate Salt

# Random salt (16 bytes hex)
openssl rand -hex 16

# Random salt (16 bytes base64)
openssl rand -base64 16

Script Examples

Generate Password Script

#!/bin/bash
# Generate a secure password

LENGTH="${1:-16}"
CHARS="${2:-A-Za-z0-9!@#$%^&*}"

openssl rand -base64 "$LENGTH" | tr -dc "$CHARS" | head -c "$LENGTH"
echo

Generate API Key

#!/bin/bash
# Generate API key (prefix_key format)

PREFIX="${1:-sk}"
openssl rand -hex 32 | sed "s/^/${PREFIX}_/"

Generate All Keys

#!/bin/bash
# Generate full set of API credentials

echo "=== API Credentials ==="
echo "Client ID: $(openssl rand -hex 16)"
echo "Client Secret: $(openssl rand -base64 32)"
echo "API Key: sk_$(openssl rand -hex 32)"
echo "JWT Secret: $(openssl rand -base64 32)"
echo ""
echo "=== Database ==="
echo "Password: $(openssl rand -base64 16)"
echo ""
echo "=== Encryption ==="
echo "Key: $(openssl rand -hex 32)"
echo "IV: $(openssl rand -hex 16)"

Security Notes

Always use cryptographically secure random generators
Never use rand() or similar pseudo-random functions
Use appropriate length (min 16 for passwords, 32 for keys)
Store hashes, never store plain text
Use unique salts for each password

Quick Commands

Task	Command
16-char password	`openssl rand -base64 16 \| tr -dc 'A-Za-z0-9' \| head -c 16`
32-char API key	`openssl rand -hex 32`
UUID	`uuidgen`
Random hex	`openssl rand -hex 16`
Random base64	`openssl rand -base64 32`

password-gen

Password Generation Skill

When to Use

Password Generation

Basic Password