medina/encrypt-image.sh

## encrypt-image.sh
#!/bin/bash -x

### Uses curl, openssl, ImageMagick (convert, identify)

### Grab an image
URL=https://avatars0.githubusercontent.com/u/54688
IMAGE=medina
curl -L $URL -o$IMAGE.png

### Extract the "raw" image
SIZE=$(identify $IMAGE.png | awk '{print $3}')
convert -depth 32 $IMAGE.png $IMAGE.rgba

### Let's get encrypting!
### $ man enc
### $ openssl enc -h
PASSWORD=itsasecret
for cipher in \
  '-des-cbc' '-des-ofb' '-des-cfb' '-des-ecb' \
  '-aes-128-cbc' '-aes-128-ofb' '-aes-128-cfb' '-aes-128-ecb'
do
  # Note that this "leaks" the password on the command-line!
  openssl enc $cipher -in $IMAGE.rgba -out ${IMAGE}${cipher}.rgba -k $PASSWORD

  # Put headers back on the raw encrypted images
  convert -size $SIZE -depth 32 ${IMAGE}${cipher}.rgba ${IMAGE}${cipher}.png
done

## question.md

      
    Raw
  

              question.md
            
          
    What's going on with these image sizes?
What do the PNG images look like?
ls -lh ${IMAGE}*.png ${IMAGE}*.rgba | awk '{printf "%9s %s\n", $5,$9}'
     1.6M medina-aes-128-cbc.png
     3.2M medina-aes-128-cbc.rgba
     1.6M medina-aes-128-cfb.png
     3.2M medina-aes-128-cfb.rgba
     338K medina-aes-128-ecb.png
     3.2M medina-aes-128-ecb.rgba
     1.6M medina-aes-128-ofb.png
     3.2M medina-aes-128-ofb.rgba
     1.6M medina-des-cbc.png
     3.2M medina-des-cbc.rgba
     1.6M medina-des-cfb.png
     3.2M medina-des-cfb.rgba
     331K medina-des-ecb.png
     3.2M medina-des-ecb.rgba
     1.6M medina-des-ofb.png
     3.2M medina-des-ofb.rgba
     209K medina.png
     3.2M medina.rgba
     ```
	#!/bin/bash -x

	### Uses curl, openssl, ImageMagick (convert, identify)

	### Grab an image
	URL=https://avatars0.githubusercontent.com/u/54688
	IMAGE=medina
	curl -L $URL -o$IMAGE.png

	### Extract the "raw" image
	SIZE=$(identify $IMAGE.png \| awk '{print $3}')
	convert -depth 32 $IMAGE.png $IMAGE.rgba

	### Let's get encrypting!
	### $ man enc
	### $ openssl enc -h
	PASSWORD=itsasecret
	for cipher in \
	'-des-cbc' '-des-ofb' '-des-cfb' '-des-ecb' \
	'-aes-128-cbc' '-aes-128-ofb' '-aes-128-cfb' '-aes-128-ecb'
	do
	# Note that this "leaks" the password on the command-line!
	openssl enc $cipher -in $IMAGE.rgba -out ${IMAGE}${cipher}.rgba -k $PASSWORD

	# Put headers back on the raw encrypted images
	convert -size $SIZE -depth 32 ${IMAGE}${cipher}.rgba ${IMAGE}${cipher}.png
	done