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//go:build !noazurekms
// +build !noazurekms
package azurekms
import (
"context"
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rsa"
"fmt"
"math/big"
"net/url"
"strings"
"time"
"github.com/Azure/azure-sdk-for-go/sdk/keyvault/azkeys"
"github.com/pkg/errors"
"go.step.sm/crypto/kms/apiv1"
"go.step.sm/crypto/kms/uri"
)
var now = func() time.Time {
return time.Now().UTC()
}
// pointer returns the pointer of v.
func pointer[T any](v T) *T {
return &v
}
// defaultContext returns the default context used in requests to azure.
func defaultContext() (context.Context, context.CancelFunc) {
return context.WithTimeout(context.Background(), 15*time.Second)
}
// getKeyName returns the uri of the key vault key.
func getKeyName(vault, name string, key *azkeys.JSONWebKey) string {
if key != nil && key.KID != nil {
if u, err := url.Parse(string(*key.KID)); err == nil {
host := strings.SplitN(u.Host, ".", 2)
path := strings.Split(u.Path, "/")
if len(host) == 2 && len(path) == 4 {
values := url.Values{
"vault": []string{host[0]},
"name": []string{path[2]},
}
uu := uri.New(Scheme, values)
uu.RawQuery = url.Values{"version": []string{path[3]}}.Encode()
return uu.String()
}
}
}
// Fallback to URI without version id.
// This will return the latest version of the key.
values := url.Values{
"vault": []string{vault},
"name": []string{name},
}
return uri.New(Scheme, values).String()
}
// parseKeyName returns the key vault, name and version from URIs like:
//
// - azurekms:vault=key-vault;name=key-name
// - azurekms:vault=key-vault;name=key-name?version=key-id
// - azurekms:vault=key-vault;name=key-name?version=key-id&hsm=true
//
// The key-id defines the version of the key, if it is not passed the latest
// version will be used.
//
// HSM can also be passed to define the protection level if this is not given in
// CreateQuery.
func parseKeyName(rawURI string, defaults defaultOptions) (vault, name, version string, hsm bool, err error) {
var u *uri.URI
u, err = uri.ParseWithScheme(Scheme, rawURI)
if err != nil {
return
}
if name = u.Get("name"); name == "" {
err = errors.Errorf("key uri %q is not valid: name is missing", rawURI)
return
}
if vault = u.Get("vault"); vault == "" {
if defaults.Vault == "" {
name = ""
err = errors.Errorf("key uri %q is not valid: vault is missing", rawURI)
return
}
vault = defaults.Vault
}
if u.Get("hsm") == "" {
hsm = (defaults.ProtectionLevel == apiv1.HSM)
} else {
hsm = u.GetBool("hsm")
}
version = u.Get("version")
return
}
func convertKey(key *azkeys.JSONWebKey) (crypto.PublicKey, error) {
if key == nil || key.Kty == nil {
return nil, errors.New("invalid key: missing kty value")
}
switch *key.Kty {
case azkeys.JSONWebKeyTypeEC, azkeys.JSONWebKeyTypeECHSM:
return ecPublicKey(key.Crv, key.X, key.Y)
case azkeys.JSONWebKeyTypeRSA, azkeys.JSONWebKeyTypeRSAHSM:
return rsaPublicKey(key.N, key.E)
case azkeys.JSONWebKeyTypeOct, azkeys.JSONWebKeyTypeOctHSM:
return octPublicKey(key.K)
default:
return nil, fmt.Errorf("invalid key: unsupported kty %q", *key.Kty)
}
}
func ecPublicKey(crv *azkeys.JSONWebKeyCurveName, x, y []byte) (crypto.PublicKey, error) {
if crv == nil {
return nil, errors.New("invalid EC key: missing crv value")
}
if len(x) == 0 || len(y) == 0 {
return nil, errors.New("invalid EC key: missing x or y values")
}
var curve elliptic.Curve
var curveSize int
switch *crv {
case azkeys.JSONWebKeyCurveNameP256:
curve = elliptic.P256()
curveSize = 32
case azkeys.JSONWebKeyCurveNameP384:
curve = elliptic.P384()
curveSize = 48
case azkeys.JSONWebKeyCurveNameP521:
curve = elliptic.P521()
curveSize = 66 // (521/8 + 1)
case azkeys.JSONWebKeyCurveNameP256K:
return nil, fmt.Errorf(`invalid EC key: crv %q is not supported`, *crv)
default:
return nil, fmt.Errorf("invalid EC key: crv %q is not supported", *crv)
}
if len(x) != curveSize || len(y) != curveSize {
return nil, errors.New("invalid EC key: x or y length is not valid")
}
key := &ecdsa.PublicKey{
Curve: curve,
X: new(big.Int).SetBytes(x),
Y: new(big.Int).SetBytes(y),
}
if !curve.IsOnCurve(key.X, key.Y) {
return nil, errors.New("invalid EC key: point (x, y) does not lie on the curve")
}
return key, nil
}
func rsaPublicKey(n, e []byte) (crypto.PublicKey, error) {
if len(n) == 0 || len(e) == 0 {
return nil, errors.New("invalid RSA key: missing n or e values")
}
return &rsa.PublicKey{
N: new(big.Int).SetBytes(n),
E: int(new(big.Int).SetBytes(e).Int64()),
}, nil
}
func octPublicKey(k []byte) (crypto.PublicKey, error) {
if k == nil {
return nil, errors.New("invalid oct key: missing k value")
}
return k, nil
}
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