Bash/shell script to Encrypt and Decrypt an arbitrary file using a passphrase

decrypt_file.sh

#!/bin/sh

set -e

# Required ENV variable: ENC_PASSPHRASE
# Usage: ENC_PASSPHRASE=my_super_long_ascii_pass_phrase123 ./decrypt_file.sh encrypted.enc secretfile.json

if [ -z "$ENC_PASSPHRASE" ]; then
  echo "ERROR: Required ENC_PASSPHRASE environment variable NOT passed in."
  exit 1
fi

decrypt () {
    gpg --batch --pinentry-mode loopback --passphrase "$ENC_PASSPHRASE" \
        -o "$2" -d "$1" >/dev/null 2>/dev/null
}

decrypt "$1" "$2"

echo "Decrypted $1 to file $2"

encrypt_file.sh

#!/bin/sh

set -e

# Required ENV variable: ENC_PASSPHRASE
# Usage: ENC_PASSPHRASE=my_super_long_ascii_pass_phrase123 ./encrypt_file.sh secretfile.json encrypted.enc 

if [ -z "$ENC_PASSPHRASE" ]; then
  echo "ERROR: Required ENC_PASSPHRASE environment variable NOT passed in."
  exit 1
fi

encr () {
  gpg --symmetric --cipher-algo AES256 --passphrase-repeat 0 --batch --pinentry-mode loopback \
    --passphrase "$ENC_PASSPHRASE" -o "$2" \
    "$1" >/dev/null 2>/dev/null
}

encr "$1" "$2"

echo "Encrypted $1 to file $2"

Encrypt Example

ENC_PASSPHRASE=my_super_long_ascii_pass_phrase123 ./encrypt_file.sh secretfile.json encrypted.enc

cat encrypted.enc # completely unreadable

Decrypt Example

ENC_PASSPHRASE=my_super_long_ascii_pass_phrase123 ./decrypt_file.sh encrypted.enc secretfile.json

cat secretfile.json # original file