17-secret

Gophercises - 17 - Secrets API and CLI

Problem

• https://github.com/gophercises/secret
• https://gophercises.com/exercises/secret

Solution

• main.go: Main functionality. Create keystore, add/update/list/delete keys.
• keystore/keystore.go: Keystore package.

Lessons Learned

Chaining Reader and Writer Interfaces

This is pretty cool. You can see it inside Encrypter and Decrypter.

In short, you pass an io.Reader or io.Writer to another and chain them. Then you write to one (or read from one) and encryption/decryption works. We have already seen this in a previous lesson where we used json.NewDecoder/NewEncoder on files or buffers.

io.TeeReader(r io.Reader, w io.Writer) io.Reader

"TeeReader returns a Reader that writes to w what it reads from r. All reads from r performed through it are matched with corresponding writes to w. There is no internal buffering ..."

• https://golang.ir/pkg/io/#TeeReader

I did not use it in this lesson, but seems like a useful thing.

Pass Arguments to Delve Debugger in VS Code

Pass the arguments inside launch.json like this.

"args": [
    "get",
    "test",
    "yolo",
    "key3",
],

Encrypter and Decrypter

I wasted a lot of time (a Sunday) debugging the code because my decrypted values where only correct for the first block. Finally, I saw I am encrypting again inside Decrypter. On a positive note, I learned how to use Delve debugger and looked at the internals of json encoder/decoder.

Usage

$ go run main.go
NAME:
   secret - secret is simple encrypted keystore.

USAGE:
   main.exe [global options] command [command options] [arguments...]

COMMANDS:
     create, c         Create a new keystore.
                       secret create [filename] [encryptionKey]
     set, s, add       Set a key/value pair in the keystore.
                       secret set [filename] [encryptionKey] [key] [value]
     get, g, retrieve  Get the value of a key from the keystore.
                       secret get [filename] [encryptionKey] [key]
     del, d, delete    Delete a key from the keystore.
                       secret del [filename] [encryptionKey] [key]
     list, l           List all keys in the keystore.
                       secret list [filename] [encryptionKey]
     help, h           Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --help, -h  show help
No commands provided.
exit status 2

$go run main.go create test.enc pass
Keystore created at test.enc.

$ go run main.go add test.enc pass key1 val1
Added key1 to keystore.
KeyStore:
Path: test.enc
Number of keys:1

$ go run main.go add test.enc pass key2 val2
Added key2 to keystore.
KeyStore:
Path: test.enc
Number of keys:2

$ go run main.go list test.enc pass
Keys in the keystore
key1
key2

$ go run main.go del test.enc pass key2
Key key2 (if exists) deleted from the keystore.
KeyStore:
Path: test.enc
Number of keys:1

$ go run main.go list test.enc pass
Keys in the keystore
key1

$ go run main.go get test.enc pass key2
keystore.Get: key2 key does not exist
exit status 3

$ go run main.go get test.enc pass key1
Value of key1 key is: val1.
KeyStore:
Path: test.enc
Number of keys:1