1[](https://goreportcard.com/report/github.com/MicahParks/keyfunc) [](https://pkg.go.dev/github.com/MicahParks/keyfunc)
2
3# keyfunc
4
5The purpose of this package is to provide a
6[`jwt.Keyfunc`](https://pkg.go.dev/github.com/golang-jwt/jwt/v4#Keyfunc) for the
7[github.com/golang-jwt/jwt/v4](https://github.com/golang-jwt/jwt) package using a JSON Web Key Set (JWK Set or JWKS) for
8parsing and verifying JSON Web Tokens (JWTs).
9
10There is legacy support for `github.com/dgrijalva/jwt-go` and its popular forks. It's in a separate project to keep this
11project minimal. If your use case supports a legacy fork, please
12see: [github.com/MicahParks/compatibility-keyfunc](https://github.com/MicahParks/compatibility-keyfunc).
13
14It's common for an identity provider, such as [Keycloak](https://www.keycloak.org/)
15or [Amazon Cognito (AWS)](https://aws.amazon.com/cognito/) to expose a JWKS via an HTTPS endpoint. This package has the
16ability to consume that JWKS and produce a
17[`jwt.Keyfunc`](https://pkg.go.dev/github.com/golang-jwt/jwt/v4#Keyfunc). It is important that a JWKS endpoint is using
18HTTPS to ensure the keys are from the correct trusted source.
19
20This repository only depends on: [github.com/golang-jwt/jwt/v4](https://github.com/golang-jwt/jwt)
21
22`jwt.Keyfunc` signatures are imported from these, implemented, then exported as methods.
23
24## Supported Algorithms
25
26Currently, this package supports JWTs signed with a `kty` that matches one of the following:
27* `EC` [Elliptic Curve Digital Signature Algorithm (ECDSA)](https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm)
28* `RSA` [Rivest–Shamir–Adleman (RSA)](https://en.wikipedia.org/wiki/RSA_(cryptosystem))
29* `OKP` [Edwards-curve Digital Signature Algorithm (EdDSA)](https://en.wikipedia.org/wiki/EdDSA)
30* `OCT` [HMAC](https://en.wikipedia.org/wiki/HMAC), [AES Key Wrap](https://en.wikipedia.org/wiki/Key_Wrap), and others
31
32Additionally, the supported `EC` elliptical curve types are below:
33* `P-256`
34* `P-384`
35* `P-521`
36
37For `OKP`, EdDSA, only the `Ed25519` curve type is supported. (I have not found a standard library package that
38supports `Ed448`.)
39
40This _does_ include HMAC keys. For an example using HMAC keys, please see the `examples/hmac` directory. Do _not_ expose
41HMAC keys in public facing JWKS, as HMAC keys are secret keys that do not use public key cryptography.
42
43If there are cryptographic algorithms, curve types, or something else already standardized that you'd like supported in
44this Go package, please open an issue or pull request.
45
46## Basic usage
47
48For complete examples, please see the `examples` directory.
49
50```go
51import "github.com/MicahParks/keyfunc"
52```
53
54#### A note on read-only keys
55The [`JWKS.ReadOnlyKeys`](https://pkg.go.dev/github.com/MicahParks/keyfunc#JWKS.ReadOnlyKeys) method returns a read-only
56copy of a `map[string]interface{}`. The key to this map is the key ID, `kid`, and the value is the cryptographic key.
57This is a useful map for use of keys within a JWKS outside of `github.com/golang-jwt/jwt/v4`.
58
59The map itself is a copy. So it can be modified safely. However, the values are of type `interface{}`. If these values
60are modified, it may cause undefined behavior.
61
62### Preconditions: Acquire the JWKS URL, JSON, or gather cryptographic keys (given keys)
63
64A JWKS URL is not required, one can be created directly from JSON with the
65[`keyfunc.NewJSON`](https://pkg.go.dev/github.com/MicahParks/keyfunc#NewJSON) function.
66
67```go
68// Get the JWKS URL from an environment variable.
69jwksURL := os.Getenv("JWKS_URL")
70
71// Confirm the environment variable is not empty.
72if jwksURL == "" {
73log.Fatalln("JWKS_URL environment variable must be populated.")
74}
75```
76
77### Step 1: Create the JWKS
78
79Via HTTP:
80```go
81// Create the JWKS from the resource at the given URL.
82jwks, err := keyfunc.Get(jwksURL, keyfunc.Options{}) // See recommended options in the examples directory.
83if err != nil {
84log.Fatalf("Failed to get the JWKS from the given URL.\nError: %s", err)
85}
86```
87Via JSON:
88```go
89// Get the JWKS as JSON.
90var jwksJSON = json.RawMessage(`{"keys":[{"kid":"zXew0UJ1h6Q4CCcd_9wxMzvcp5cEBifH0KWrCz2Kyxc","kty":"RSA","alg":"PS256","use":"sig","n":"wqS81x6fItPUdh1OWCT8p3AuLYgFlpmg61WXp6sp1pVijoyF29GOSaD9xE-vLtegX-5h0BnP7va0bwsOAPdh6SdeVslEifNGHCtID0xNFqHNWcXSt4eLfQKAPFUq0TsEO-8P1QHRq6yeG8JAFaxakkaagLFuV8Vd_21PGJFWhvJodJLhX_-Ym9L8XUpIPps_mQriMUOWDe-5DWjHnDtfV7mgaOxbBvVo3wj8V2Lmo5Li4HabT4MEzeJ6e9IdFo2kj_44Yy9osX-PMPtu8BQz_onPgf0wjrVWt349Rj6OkS8RxlNGYeuIxYZr0TOhP5F-yEPhSXDsKdVTwPf7zAAaKQ","e":"AQAB","x5c":["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"],"x5t":"IYIeevIT57t8ppUejM42Bqx6f3I","x5t#S256":"TuOrBy2NcTlFSWuZ8Kh8W8AjQagb4fnfP1SlKMO8-So"},{"kid":"ebJxnm9B3QDBljB5XJWEu72qx6BawDaMAhwz4aKPkQ0","kty":"EC","alg":"ES512","use":"sig","crv":"P-521","x":"YQ95Xj8MTzcHytbU1h8YkCN2kdEQA7ThuZ1ctB9Ekiw6tlM9RwL62eQvzEt4Rz8qN69uRqgU9RzxQOkSU5xVvyo","y":"SMMuP3QnAPHtx7Go2ARsG3NBaySWBLmVvS8s2Ss7Vm_ISWenNbdjKOsY1XvtiQz5scGzWDCEUoZzgV8Ve1mLOV0"},{"kid":"TVAAet63O3xy_KK6_bxVIu7Ra3_z1wlB543Fbwi5VaU","kty":"EC","alg":"ES384","use":"sig","crv":"P-384","x":"Pik2o5as-evijFABH5p6YLXHnWw8iQ_N1ummPY1c_UgG6NO0za-gNOhTz2-tsd_w","y":"e98VSff71k19SY_mHgp3707lgQVrhfVpiGa-sGaKxOWVpxd2jWMhB0Q4RpSRuCp5"},{"kid":"arlUxX4hh56rNO-XdIPhDT7bqBMqcBwNQuP_TnZJNGs","kty":"RSA","alg":"RS512","use":"sig","n":"hhtifu8LL3ICE3BAX5l1KZv6Lni0lhlhBusSfepnpxcb4C_z2U71cQTnLY27kt8WB4bNG6e5_KMx9K3xUdd3euj9MCq8vytwEPieeHE1KXQuhJfLv017lhpK_dRMOHyc-9-50YNdgs_8KWRkrzjjuYrCiO9Iu76n5319e-SC8OPvNUglqxp2N0Sp2ltne2ZrpN8T3OEEXT62TSGmLAVopRGw5gllNVrJfmEyZJCRrBM6s5CQcz8un0FjkAAC4DI6QD-eBL0qG3_NR0hQvR1he2o4BLwjOKH45Pk_jj-eArp-DD6Xq6ABQVb5SNOSdaxl5lnmuotRoY3G5d9YSl-K3w","e":"AQAB","x5c":["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"],"x5t":"geiCPGtT_10T8xGLUK1LA0_YQEE","x5t#S256":"dLp3_QNGwMbYll5VecnR8Q9NSeFVfqJPBTa2_8qf48I"},{"kid":"tW6ae7TomE6_2jooM-sf9N_6lWg7HNtaQXrDsElBzM4","kty":"RSA","alg":"PS512","use":"sig","n":"p32N7jqKfMUB6_dKY1uZ3wizzPlBAXg9XrntfUcwNLRPfTBnshpt4uQBf3T8fexkbzhtR18oHvim-YvcWfC5eLGQmWHYiVwACa_C7oGqx51ijK2LRbUg4TKhnZX2X3Ld9xvr3HsosKh2UXn_Ay8nuvdfH-U6S7btT6a-AIFlt3BpqZP0EOl7rY-ie8nXoA13xX6BoyzYiNcugdYCU6czQcmTIJ1JLS0zohi4aTNehRt-1VMRpIMx7q7Ouq3Zhbi7RcDo-_D8FPRhWc2eEKd-h8ebFTIxEOrkguBIomjEFTf3SfYbOB_h-14v9Q2yz-NzyId3-ujRCQGC0hn-cixe2w","e":"AQAB","x5c":["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"],"x5t":"f1l1fxICz1fe9mI-sSrtc19EDhU","x5t#S256":"NUJWRA4ADpLEg_SMkSoE4FKQN0H1Tlz85L-i7puVcqQ"},{"kid":"Lx1FmayP2YBtxaqS1SKJRJGiXRKnw2ov5WmYIMG-BLE","kty":"RSA","alg":"PS384","use":"sig","n":"q7WM4SnrdzlFSo_A1DRhc-8Ho-pBsfs49kGRbw3O_OKFIUyZrzHaRuovW_QaEAyiO3HX8CNcGPcpHdmpl4DhTGEBLcd6xXtCaa65ct00Mq7ZHCRRCrKLh6lJ0rY9fP8vCV0RBigpkNoRfrqLQQN4VeVFTbGSrDaS0LzPbap0-q5FKXUR-OQmQEtOupXhKFQtbB73tL83YnG6Swl7nXsx54ulEoDzcCCYt7pjCVVp7L9fzI2_ucTdtQclAJVQZGKpsx7vabOJuiMUwuAIz56lOJyXRMePsW8UogwC4FA2A52STsYlhOPsDEW4iIExFVNqs-CGoDGhYLIavaCkZhXM0w","e":"AQAB","x5c":["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"],"x5t":"fjRYR1986VCLzbaZaw5r25UKahw","x5t#S256":"ZHNHpizlsjD3qSZh7gJQQBu8W9jBL2HR0y7-3u2Wb-g"},{"kid":"gnmAfvmlsi3kKH3VlM1AJ85P2hekQ8ON_XvJqs3xPD8","kty":"RSA","alg":"RS384","use":"sig","n":"qUNQewKl3APQcbpACMNJ2XphPpupt395z6OZvj5CW9tiRXY3J7dqi8U0bWoIhtmmc7Js6hjp-A5W_FVStuXlT1hLyjJsHeu9ZVPnfIl2MnYN83zQBKw8E4mFsVv0UXNvkVPBF_k0yXrz-ABleWLOgFGnkNU9csc3Z5aihHcwRmC_oS7PZ9Vc-l0xBCyF3YRHI-al8ppSHwFreOweF3-JP3poNAXd906_tjX2KlHSJmNqcUNiSfEluyCp02ALlRFKXUQ1HlfSupHcHySDlanfUyIzZgM9ysCvC1vfNdAuwZ44oUBMul_XPxxhzlewL2Y8PtSDLUDWGTIou8M8049D8Q","e":"AQAB","x5c":["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"],"x5t":"CmRnQVduZWtEsdOC4mauUUsSWxA","x5t#S256":"BvC0LmuM8ZIApN3TQQZWWbGO-d082Ah5d3D6vPvahGw"},{"kid":"CGt0ZWS4Lc5faiKSdi0tU0fjCAdvGROQRGU9iR7tV0A","kty":"EC","alg":"ES256","use":"sig","crv":"P-256","x":"DPW7n9yjfE6Rt-VvVmEdeu4QdW44qifocAPPDxACDDY","y":"-ejsVw8222-hg2dJWx3QV0hE4-I0Ujp7ZsWebE68JE0"},{"kid":"C65q0EKQyhpd1m4fr7SKO2He_nAxgCtAdws64d2BLt8","kty":"RSA","alg":"RS256","use":"sig","n":"ja99ybDrLvw11Z4CvNlDI-kkqJEBpSnvDf0pZF2DvBlvYmeVYL_ChqIe8E9GyHUmLMdtO_jifSgOqE5b8vILwi1kZnJR7N857uEnbWM9YTeevi_RZ-E_hr4frW2NKJ78YGvCzwLKG2GgtSjj0zuTLnSaK8fCGzqXgy6paXNhgHUSZgGwvO0YItpMlyJeqEj1wGTWz1IyA1sguF1cC7K0fojPbPoBwrhvaAeoGRPLraE0rrBsQv8iiLwnRBIez9B1j0NiUG8Iad953Y7UzaKOAw8crIEK45NIK_yxHUpxqcHLjPIcRyIyJGioRyGK7cp-_7iPLOCutQc-u46mom1_ZQ","e":"AQAB","x5c":["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"],"x5t":"5GNr3LeRXHWI4YR8-QTSsF98oTI","x5t#S256":"Dgd0_wZZqvRuf4GEISPNHREX-1ixTMIsrPeGzk0bCxs"}]}`)
91
92// Create the JWKS from the resource at the given URL.
93jwks, err := keyfunc.NewJSON(jwksJSON)
94if err != nil {
95log.Fatalf("Failed to create JWKS from JSON.\nError: %s", err)
96}
97```
98Via a given key:
99```go
100// Get an HMAC key.
101key := []byte("example secret")
102uniqueKeyID := "myKeyID"
103
104// Create the JWKS from the HMAC key.
105jwks := keyfunc.NewGiven(map[string]keyfunc.GivenKey{
106uniqueKeyID: keyfunc.NewGivenHMAC(key),
107})
108```
109
110Additional options can be passed to the [`keyfunc.Get`](https://pkg.go.dev/github.com/golang-jwt/jwt/v4/keyfunc#Get)
111function. See [`keyfunc.Options`](https://pkg.go.dev/github.com/golang-jwt/jwt/v4/keyfunc#Options) and the additional
112features mentioned at the bottom of this `README.md`.
113
114### Step 2: Use the [`JWKS.Keyfunc`](https://pkg.go.dev/github.com/golang-jwt/jwt/v4/keyfunc#JWKS.Keyfunc) method as the [`jwt.Keyfunc`](https://pkg.go.dev/github.com/golang-jwt/jwt/v4#Keyfunc) when parsing tokens
115
116```go
117// Parse the JWT.
118token, err := jwt.Parse(jwtB64, jwks.Keyfunc)
119if err != nil {
120return nil, fmt.Errorf("failed to parse token: %w", err)
121}
122```
123
124The [`JWKS.Keyfunc`](https://pkg.go.dev/github.com/MicahParks/keyfunc#JWKS.Keyfunc) method will automatically select the
125key with the matching `kid` (if present) and return its public key as the correct Go type to its caller.
126
127## Test coverage
128
129Test coverage is currently `>85%`.
130
131Testing could be improved by signing all JWTs during the tests themselves. Alternatively, using JWTs that do not expire
132would accomplish the same purpose. There are some hard-coded JWTs which are expired. This means the tests with hard
133coded JWTs cannot check for parsing and validation errors, just errors within the `jwt.Keyfunc` itself.
134
135## Additional features
136These features can be configured by populating fields in the
137[`keyfunc.Options`](https://pkg.go.dev/github.com/MicahParks/keyfunc#Options) argument to the
138[`keyfunc.Get`](https://pkg.go.dev/github.com/MicahParks/keyfunc#Get) function.
139* A background refresh of the JWKS keys can be performed.
140 * A custom background refresh interval can be specified. For an example, please see the `examples/interval`
141 directory.
142 * A custom background refresh request context timeout can be specified. Defaults to one minute. For an example,
143 please see the `examples/ctx` directory.
144 * A custom background refresh error handling function can be specified. If none is specified, errors go unhandled
145 silently. For an example, please see the `examples/recommended_options` directory.
146 * A custom rate limit can be specified to prevent too many requests for a JWKS refresh. For an example, please see
147 the `examples/recommended_options` directory.
148 * JWTs with a previously unseen `kid` can prompt an automatic refresh of the remote JWKS resource. This should be
149 paired with `RefreshRateLimit` to prevent abuse. For an example, please see the `examples/recommended_options`
150 directory.
151* A custom HTTP client can be used.
152* A custom HTTP request factory can be provided to create HTTP requests for the remote JWKS resource. For example, an
153 HTTP header can be added to indicate a User-Agent.
154* A custom HTTP response extractor can be provided to get the raw JWKS JSON from the `*http.Response`. For example, the
155 HTTP response code could be checked. Implementations are responsible for closing the response body.
156 * By default,
157 the [`keyfunc.ResponseExtractorStatusOK`](https://pkg.go.dev/github.com/MicahParks/keyfunc#ResponseExtractorStatusOK)
158 function is used. The default behavior changed in `v1.4.0`.
159* A custom whitelist of acceptable JSON Web Key `"use"` parameter values can be specified. Values not whitelisted will
160 cause an error from the [`.Keyfunc`](https://pkg.go.dev/github.com/MicahParks/keyfunc#JWKS.Keyfunc) method. This
161 whitelist can be disabled with the `JWKUseNoWhitelist` option.
162 * By default, only JSON Web Keys with a `"use"` parameter value of `"sig"`, an empty string `""`, or a completely
163 omitted `"use"` parameter will be returned. The default behavior changed in `v1.5.0`.
164 * This `"use"` whitelisting behavior is only available with `keyfunc.Get`. It is not available with
165 `keyfunc.NewJSON` or `keyfunc.NewGiven`. Please open a GitHub issue if you would like this feature added to the
166 other creation methods.
167* A map of JWT key IDs (`kid`) to keys can be given and used for the `jwt.Keyfunc`. For an example, see
168 the `examples/given` directory.
169* A copy of the latest raw JWKS `[]byte` can be returned.
170* Custom cryptographic algorithms can be used. Make sure to
171 use [`jwt.RegisterSigningMethod`](https://pkg.go.dev/github.com/golang-jwt/jwt/v4#RegisterSigningMethod) before
172 parsing JWTs. For an example, see the `examples/custom` directory.
173
174## Notes
175Trailing padding is required to be removed from base64url encoded keys inside a JWKS. This is because RFC 7517 defines
176base64url the same as RFC 7515 Section 2:
177* https://datatracker.ietf.org/doc/html/rfc7517#section-1.1
178* https://datatracker.ietf.org/doc/html/rfc7515#section-2
179
180However, this package will remove trailing padding on base64url encoded keys to account for improper implementations of
181JWKS.
182
183## References
184This project was built and tested using various RFCs and services. The services are listed below:
185* [Keycloak](https://www.keycloak.org/)
186* [Sample JWKS Service](https://jwks-service.appspot.com/)
187* connect2id's [Server JWKSet Gen](https://connect2id.com/products/server/docs/config/jwk-set)
188 ([Source](https://bitbucket.org/connect2id/server-jwkset-gen/src/master/))
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