Encrypt a file with a given pubic key (to send to someone else)

encrypt.sh

#!/bin/bash
# Encrypt a file using the specified public key

# Source file
SRCF=$1

# Public key
PUBK=$2

# Encrypted file (defaults to the encrypted file name + ".encrypted")
ENCF=${3:-$SRCF.encrypted}

if [ -f "$ENCF" ]; then
	echo "File with the encrypted filename already exists"
	exit
fi

openssl rsautl -encrypt -inkey $PUBK -pubin -in $SRCF -out $ENCF

exit

# To use this:
# sh encrypt.sh /path/to/file.ext /path/to/publickey.pub

# To give specific name to the encrypted file:
# sh encrypt.sh /path/to/file.ext /path/to/publickey.pub /path/to/encrypted.file