URL signing package for Go.
- You can jump straight into the API documentation.
Signature secures web calls by generating a security hash on the client (using a private key shared with the server), to ensure that the request is geniune. Only a client who knows the private key will be able to generate the same security hash.
Since the private key is only used to generate the security hash and not transmitted with the request (only some kind of public key is), the server and client must agree on the private key in order for the hash to be verified.
Request signing entails generating a hash based on the details of the request, PLUS a private key - and having the remote server try to generate the same hash, assuming you both agree on the private key.
Before signing the request, you must:
- Generate the original request URL
- example: http://something.com?key=value&key2=value2
- Add the public key value to the request URL
- example: http://something.com?key=value&key2=value2?key=85Bad53987b3d851
SignatureKey parameter generation:
To generate a signature for the request, the Signature package does the following:
- Create a copy of the request URL
- Add
PrivateKeyKeykey parameter - Add
BodyHashKeyvalue containing an SHA-1 hash of the body contents if there is a body - otherwise, skip this step (and do not add aBodyHashKeyparameter at all) - Order parameters alphabetically. Order first by keys, and if there are multiple values for one key (i.e. ?color=red&color=blue) then order the values alphabetically afterwards.
- Prefix it with the HTTP method (in uppercase) followed by an ampersand (i.e.
GET&http://...) - Hash it (using SHA-1)
- Add the hash as
SignatureKeyto the end of the original URL
To verify a signed request, the Signature package does the following:
- Strip off the
SignatureKeyparameter (and keep it) - Lookup the account (using the public key) and get the
PrivateKeyKeyparameter, and add it to the URL - Hash it
- Compare the generated hash with the
SignatureKeyvalue to decide if it the request is valid or not
The signature package provides some settings to allow you to use non-default field names in your code. Remember that the client needs to use the same fields in order for the security hashes to match.
// PrivateKeyKey is the key (URL field) for the private key.
signature.PrivateKeyKey string = "~private"
// BodyHashKey is the key (URL field) for the body hash used for signing requests.
signature.BodyHashKey string = "~bodyhash"
// SignatureKey is the key (URL field) for the signature of requests.
signature.SignatureKey string = "~sign"
To validate your code is generating the correct hash, ensure it generates the following output.
GET http://test.stretchr.com/api/v2?:name=!Mat&:name=!Laurie&:age=>20
Public key: ABC123
Private key: ABC123-private
Body: body
http://test.stretchr.com/api/v2?:name=!Mat&:name=!Laurie&:age=>20
http://test.stretchr.com/api/v2?~key=ABC123&:name=!Mat&:name=!Laurie&:age=>20&~key=ABC123
http://test.stretchr.com/api/v2?~key=ABC123&:name=!Mat&:name=!Laurie&:age=>20&~key=ABC123&~private=ABC123-private
Add the body hash containing an SHA-1 hash of the body contents if there is a body - otherwise, skip this step (and do not add a BodyHashKey parameter at all)
In this case, since "body" is the body, it will be hashed as 02083f4579e08a612425c0c1a17ee47add783b94.
http://test.stretchr.com/api/v2?~key=ABC123&:name=!Mat&:name=!Laurie&:age=>20&~key=ABC123&~private=ABC123-private&bodyhash=02083f4579e08a612425c0c1a17ee47add783b94
Order first by keys, and if there are multiple values for one key (i.e. ?color=red&color=blue) then order the values alphabetically afterwards.
http://test.stretchr.com/api/v2?:age=>20&:name=!Laurie&:name=!Mat&bodyhash=02083f4579e08a612425c0c1a17ee47add783b94&~key=ABC123&~private=ABC123-private
Append the HTTP method in uppercase, followed by an ampersand &:
GET&http://test.stretchr.com/api/v2?:age=>20&:name=!Laurie&:name=!Mat&bodyhash=02083f4579e08a612425c0c1a17ee47add783b94&~key=ABC123&~private=ABC123-private
6c3dc03b3f85c9eb80ed9e4bd21e82f1bbda5b8d
http://test.stretchr.com/api/v2?~key=ABC123&:name=!Mat&:name=!Laurie&:age=>20&~key=ABC123&~private=ABC123-private&~sign=6c3dc03b3f85c9eb80ed9e4bd21e82f1bbda5b8d
Response signing refers to generating a hash based on the response, to validate that the remote server indeed was responsible for generating the response. This prevents clients of the service from being tricked into accepting a response from an unreliable source.
Signature provides the HashWithKeys method that allows you to hash a series of bytes (along with the public and private keys). When this value is transmitted to the client, they can attempt to generate the same hash. If the hashes match, then the response was geniune.
Please feel free to submit issues, fork the repository and send pull requests!
When submitting an issue, we ask that you please include steps to reproduce the issue so we can see it on our end also!
Copyright (c) 2012 - 2013 Mat Ryer and Tyler Bunnell
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