mjwt/signer.go

117 lines
3.5 KiB
Go

package mjwt
import (
"crypto/rsa"
"crypto/x509"
"github.com/golang-jwt/jwt/v4"
"io"
"os"
"time"
)
// defaultMJwtSigner implements Signer and uses an rsa.PrivateKey and issuer name
// to generate MJWT tokens
type defaultMJwtSigner struct {
issuer string
key *rsa.PrivateKey
verify *defaultMJwtVerifier
}
var _ Signer = &defaultMJwtSigner{}
var _ Verifier = &defaultMJwtSigner{}
// NewMJwtSigner creates a new defaultMJwtSigner using the issuer name and rsa.PrivateKey
func NewMJwtSigner(issuer string, key *rsa.PrivateKey) Signer {
return &defaultMJwtSigner{
issuer: issuer,
key: key,
verify: newMJwtVerifier(&key.PublicKey),
}
}
// NewMJwtSignerFromFileOrCreate creates a new defaultMJwtSigner using the path
// of a rsa.PrivateKey file. If the file does not exist then the file is created
// and a new private key is generated.
func NewMJwtSignerFromFileOrCreate(issuer, file string, random io.Reader, bits int) (Signer, error) {
privateKey, err := readOrCreatePrivateKey(file, random, bits)
if err != nil {
return nil, err
}
return NewMJwtSigner(issuer, privateKey), nil
}
// NewMJwtSignerFromFile creates a new defaultMJwtSigner using the path of a
// rsa.PrivateKey file.
func NewMJwtSignerFromFile(issuer, file string) (Signer, error) {
raw, err := os.ReadFile(file)
if err != nil {
return nil, err
}
key, err := x509.ParsePKCS1PrivateKey(raw)
if err != nil {
return nil, err
}
return NewMJwtSigner(issuer, key), nil
}
// Issuer returns the name of the issuer
func (d *defaultMJwtSigner) Issuer() string { return d.issuer }
// GenerateJwt generates and returns a JWT string using the sub, id, duration and claims
func (d *defaultMJwtSigner) GenerateJwt(sub, id string, aud jwt.ClaimStrings, dur time.Duration, claims Claims) (string, error) {
return d.SignJwt(wrapClaims[Claims](d, sub, id, aud, dur, claims))
}
// SignJwt signs a jwt.Claims compatible struct, this is used internally by
// GenerateJwt but is available for signing custom structs
func (d *defaultMJwtSigner) SignJwt(wrapped jwt.Claims) (string, error) {
token := jwt.NewWithClaims(jwt.SigningMethodRS512, wrapped)
return token.SignedString(d.key)
}
// VerifyJwt validates and parses MJWT tokens see defaultMJwtVerifier.VerifyJwt()
func (d *defaultMJwtSigner) VerifyJwt(token string, claims baseTypeClaim) (*jwt.Token, error) {
return d.verify.VerifyJwt(token, claims)
}
func (d *defaultMJwtSigner) PrivateKey() *rsa.PrivateKey { return d.key }
func (d *defaultMJwtSigner) PublicKey() *rsa.PublicKey { return d.verify.pub }
// readOrCreatePrivateKey returns the private key it the file already exists,
// generates a new private key and saves it to the file, or returns an error if
// reading or generating failed.
func readOrCreatePrivateKey(file string, random io.Reader, bits int) (*rsa.PrivateKey, error) {
// read the file or return nil
f, err := readOrEmptyFile(file)
if err != nil {
return nil, err
}
if f == nil {
// generate a new key
key, err := rsa.GenerateKey(random, bits)
if err != nil {
return nil, err
}
// write the key to the file
err = os.WriteFile(file, x509.MarshalPKCS1PrivateKey(key), 0600)
return key, err
} else {
// try to parse the private key
return x509.ParsePKCS1PrivateKey(f)
}
}
// readOrEmptyFile returns bytes and errors from os.ReadFile or (nil, nil) if the
// file does not exist.
func readOrEmptyFile(file string) ([]byte, error) {
raw, err := os.ReadFile(file)
if err == nil {
return raw, nil
}
if os.IsNotExist(err) {
return nil, nil
}
return nil, err
}