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secret.go
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secret.go
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package crypt
import (
"crypto/sha256"
"github.com/aukilabs/go-tooling/pkg/errors"
)
type hdsClient interface {
Secret() string
}
type cacher func(func() ([]byte, error)) ([]byte, error)
// A secret provider using Hagall token from HDS client.
type HagallSecretProvider struct {
client hdsClient
cacher
}
// Returns a new HagallSecretProvider.
func NewHagallSecretProvider(client hdsClient) HagallSecretProvider {
return HagallSecretProvider{
client: client,
cacher: keyCacher(client),
}
}
// GetKey generates a 256-bit key using sha256 hash of Hagall secret with cache.
func (h HagallSecretProvider) GetKey() ([]byte, error) {
return h.cacher(h.getKey)
}
// getKey generates a 256-bit key using sha256 hash of Hagall secret.
func (h HagallSecretProvider) getKey() ([]byte, error) {
return sha256hash([]byte(h.client.Secret()))
}
func sha256hash(buf []byte) ([]byte, error) {
hash := sha256.New()
_, err := hash.Write([]byte(buf))
if err != nil {
return nil, errors.New("failed to hash secret").Wrap(err)
}
return hash.Sum(nil), nil
}
// keyCacher returns cacher function that caches key generated from fn.
// Cache is invalidated when client secret changes.
func keyCacher(client hdsClient) cacher {
var cachedSecret string
var cachedKey []byte
return func(fn func() ([]byte, error)) ([]byte, error) {
var err error
if len(cachedKey) == 0 ||
cachedSecret != client.Secret() {
cachedKey, err = fn()
if err != nil {
return nil, err
}
cachedSecret = client.Secret()
}
return cachedKey, nil
}
}