Encrypting Ed(1)

November 5, 2019

When I introduced the topic crypt(1) last week my actual goal was to write an editing script using ed on an encrypted file; that’s when I realized that crypt(1) was missing and that ed no longer had an -x flag. I didn’t want anything fancy, just basic encryption. I knew the old crypt(1) was no good (actually, it was no good when it was introduced forty years ago) but I was surprised that Unix and Linux had not kept up with some kind of encryption. Humbug!

Your task is to enhance ed by adding the -x encryption flag. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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