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package jwt
import (
"sync"
)
var signingMethods = map[string]func() SigningMethod{}
var signingMethodLock = new(sync.RWMutex)
// SigningMethod can be used add new methods for signing or verifying tokens. It
// takes a decoded signature as an input in the Verify function and produces a
// signature in Sign. The signature is then usually base64 encoded as part of a
// JWT.
type SigningMethod interface {
Verify(signingString string, sig []byte, key interface{}) error // Returns nil if signature is valid
Sign(signingString string, key interface{}) ([]byte, error) // Returns signature or error
Alg() string // returns the alg identifier for this method (example: 'HS256')
}
// RegisterSigningMethod registers the "alg" name and a factory function for signing method.
// This is typically done during init() in the method's implementation
func RegisterSigningMethod(alg string, f func() SigningMethod) {
signingMethodLock.Lock()
defer signingMethodLock.Unlock()
signingMethods[alg] = f
}
// GetSigningMethod retrieves a signing method from an "alg" string
func GetSigningMethod(alg string) (method SigningMethod) {
signingMethodLock.RLock()
defer signingMethodLock.RUnlock()
if methodF, ok := signingMethods[alg]; ok {
method = methodF()
}
return
}
// GetAlgorithms returns a list of registered "alg" names
func GetAlgorithms() (algs []string) {
signingMethodLock.RLock()
defer signingMethodLock.RUnlock()
for alg := range signingMethods {
algs = append(algs, alg)
}
return
}
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