go-anon

This is a fairly simple anonymisation library for Go. If you're logging some requests with sensitive fields, you should obfuscate them. This library offers several ways to obfuscate data, some completely erasing any traceability, others keeping some metadata (length, presence of non-ascii chars) to help with any debugging you'd like to do.

The following functions are available:

• Stars/"stars": replaces with "****"
• Empty/"empty": replaces with ""
• StarsWithLen/"stars_with_len": replaces with a number of asterisks equal to length
• WithInfo/"with_info": replaces with info (original string length and whether it is ASCII)
• SHA512/"sha512": replaces with a SHA-512 hash.

There are three ways to use this library:

• Marshal: Call this with a pointer to a struct and the marshal function you'd like to use, and it will anonymise the fields you've setup with tags:

   type Thing struct {
   	ID 		  string `json:"id"`
   	Sensitive string `json:"sensitive" anon:"stars"`
   }
  
   ...
  
   thing := Thing{
   	ID: "111",
   	Sensitive: "password123",
   }
   str, err := anon.Marshal(thing, json.Marshal)
   // Result:
   // {
   // 	"id": "111",
   // 	"sensitive": "****",
   // }

• Anonymise: same as above, but you're just changing the struct and not outputting marshalled data. There's also AnonymiseByRef if you want to replace the value in-place.

  anonymised, err := anon.Anonymise(thing)
  err := anon.AnonymiseByRef(&thing)
  // Result:
  // Thing {
  // 	ID: "111",
  // 	Sensitive: "****",
  // }

• Calling the functions themselves to replace a single string.

  thing.Sensitive := anon.WithInfo(thing.Sensitive) 
  // Result: 
  // Sensitive = "len:11,is_ascii:true"

Here's a more complex example:

type test struct {
	ToStar      string   `json:"to_star" anon:"stars"`
	ToEmpty     string   `json:"to_empty" anon:"empty"`
	ToLen       string   `json:"to_len" anon:"stars_with_len"`
	ToInfo      string   `json:"to_info" anon:"with_info"`
	ToInfoRune  string   `json:"to_info_rune" anon:"with_info"`
	ToIgnore    string   `json:"to_ignore"`
	ToSHA       string   `json:"to_sha" anon:"sha512"`
	Inner       inner    `json:"inner"`
	Slice       []string `json:"slice" anon:"stars_with_len"`
	SliceIgnore []string `json:"slice_ignore"`
	StructSlice []inner  `json:"struct_slice"`
}

type inner struct {
	innerString string `json:"inner_string" anon:"stars"`
}

anon.Marshal(&test{
	ToStar:      "My god, it's full of stars!",
	ToEmpty:     "will be erased",
	ToLen:       "swear-word",
	ToInfo:      "Through the fence, between the curling flower spaces, I could see them hitting.",
	ToInfoRune:  "Para a aventura indefinida, para o Mar Absoluto, para realizar o Impossível!",
	ToIgnore:    "will not change",
	ToSHA:       "hash me please",
	Inner:       inner{innerString: "will be asterisks"},
	Slice:       []string{"123", "1234", "á"},
	SliceIgnore: []string{"kept as-is"},
	StructSlice: []inner{{innerString: "12"}, {innerString: "23"}},
}, json.Marshal)

With the result below:

{
  "to_star": "****",
  "to_empty": "",
  "to_len": "**********",
  "to_info": "len:79,is_ascii:true",
  "to_info_rune": "len:77,is_ascii:false",
  "to_ignore": "will not change",
  "to_sha": "��|�-\r\\\u00186*���%�/~�t�]\u001fP��>�0��K�\u0018�d\"5��[�2�)��\u000f\"\u0014��:8�{H�\u001c#Cc��V",
  "inner": {
    "inner_string": "****"
  },
  "slice": [
    "***",
    "****",
    "**"
  ],
  "slice_ignore": [
    "kept as-is"
  ],
  "struct_slice": [
    {
      "inner_string": "****"
    },
    {
      "inner_string": "****"
    }
  ]
}