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package secure
import (
"crypto"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rsa"
"encoding/base64"
"fmt"
"github.com/go-acme/lego/v4/acme/api/internal/nonces"
jose "gopkg.in/square/go-jose.v2"
)
// JWS Represents a JWS.
type JWS struct {
privKey crypto.PrivateKey
kid string // Key identifier
nonces *nonces.Manager
}
// NewJWS Create a new JWS.
func NewJWS(privateKey crypto.PrivateKey, kid string, nonceManager *nonces.Manager) *JWS {
return &JWS{
privKey: privateKey,
nonces: nonceManager,
kid: kid,
}
}
// SetKid Sets a key identifier.
func (j *JWS) SetKid(kid string) {
j.kid = kid
}
// SignContent Signs a content with the JWS.
func (j *JWS) SignContent(url string, content []byte) (*jose.JSONWebSignature, error) {
var alg jose.SignatureAlgorithm
switch k := j.privKey.(type) {
case *rsa.PrivateKey:
alg = jose.RS256
case *ecdsa.PrivateKey:
if k.Curve == elliptic.P256() {
alg = jose.ES256
} else if k.Curve == elliptic.P384() {
alg = jose.ES384
}
}
signKey := jose.SigningKey{
Algorithm: alg,
Key: jose.JSONWebKey{Key: j.privKey, KeyID: j.kid},
}
options := jose.SignerOptions{
NonceSource: j.nonces,
ExtraHeaders: map[jose.HeaderKey]interface{}{
"url": url,
},
}
if j.kid == "" {
options.EmbedJWK = true
}
signer, err := jose.NewSigner(signKey, &options)
if err != nil {
return nil, fmt.Errorf("failed to create jose signer: %w", err)
}
signed, err := signer.Sign(content)
if err != nil {
return nil, fmt.Errorf("failed to sign content: %w", err)
}
return signed, nil
}
// SignEABContent Signs an external account binding content with the JWS.
func (j *JWS) SignEABContent(url, kid string, hmac []byte) (*jose.JSONWebSignature, error) {
jwk := jose.JSONWebKey{Key: j.privKey}
jwkJSON, err := jwk.Public().MarshalJSON()
if err != nil {
return nil, fmt.Errorf("acme: error encoding eab jwk key: %w", err)
}
signer, err := jose.NewSigner(
jose.SigningKey{Algorithm: jose.HS256, Key: hmac},
&jose.SignerOptions{
EmbedJWK: false,
ExtraHeaders: map[jose.HeaderKey]interface{}{
"kid": kid,
"url": url,
},
},
)
if err != nil {
return nil, fmt.Errorf("failed to create External Account Binding jose signer: %w", err)
}
signed, err := signer.Sign(jwkJSON)
if err != nil {
return nil, fmt.Errorf("failed to External Account Binding sign content: %w", err)
}
return signed, nil
}
// GetKeyAuthorization Gets the key authorization for a token.
func (j *JWS) GetKeyAuthorization(token string) (string, error) {
var publicKey crypto.PublicKey
switch k := j.privKey.(type) {
case *ecdsa.PrivateKey:
publicKey = k.Public()
case *rsa.PrivateKey:
publicKey = k.Public()
}
// Generate the Key Authorization for the challenge
jwk := &jose.JSONWebKey{Key: publicKey}
thumbBytes, err := jwk.Thumbprint(crypto.SHA256)
if err != nil {
return "", err
}
// unpad the base64URL
keyThumb := base64.RawURLEncoding.EncodeToString(thumbBytes)
return token + "." + keyThumb, nil
}
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