51 lines
1.4 KiB
Go
51 lines
1.4 KiB
Go
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package authjwt
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import (
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"crypto/rsa"
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"crypto/x509"
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"encoding/pem"
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"fmt"
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"github.com/golang-jwt/jwt/v5"
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)
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var _ Verifier = (*rsaPublicVerifier)(nil)
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type rsaPublicVerifier struct{ public *rsa.PublicKey }
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// NewRSAPublicKeyVerifier returns a Verifier backed by an RSA public key.
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// Use this in services that verify tokens but never issue them.
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func NewRSAPublicKeyVerifier(publicKey *rsa.PublicKey) Verifier {
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return &rsaPublicVerifier{public: publicKey}
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}
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// NewRSAPublicKeyVerifierFromPEM parses a PKIX or PKCS#1 PEM-encoded RSA public key.
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func NewRSAPublicKeyVerifierFromPEM(pemKey []byte) (Verifier, error) {
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block, _ := pem.Decode(pemKey)
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if block == nil {
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return nil, fmt.Errorf("no PEM block found")
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}
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pub, err := x509.ParsePKIXPublicKey(block.Bytes)
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if err != nil {
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rsaPub, err2 := x509.ParsePKCS1PublicKey(block.Bytes)
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if err2 != nil {
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return nil, fmt.Errorf("parse RSA public key: %w", err)
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}
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return NewRSAPublicKeyVerifier(rsaPub), nil
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}
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rsaPub, ok := pub.(*rsa.PublicKey)
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if !ok {
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return nil, fmt.Errorf("PEM key is not an RSA public key")
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}
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return NewRSAPublicKeyVerifier(rsaPub), nil
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}
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func (v *rsaPublicVerifier) Verify(tokenString string) (*jwt.Token, error) {
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return jwt.Parse(tokenString, func(t *jwt.Token) (any, error) {
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if _, ok := t.Method.(*jwt.SigningMethodRSA); !ok {
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return nil, fmt.Errorf("unexpected signing method %q", t.Header["alg"])
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}
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return v.public, nil
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}, jwt.WithJSONNumber())
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}
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