forked from mirror/jwt
148 lines
3.5 KiB
Go
148 lines
3.5 KiB
Go
package jwt
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import (
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"crypto"
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"crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"encoding/pem"
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"errors"
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)
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type SigningMethodRSA struct {
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Name string
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Hash crypto.Hash
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}
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var (
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SigningMethodRS256 *SigningMethodRSA
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SigningMethodRS384 *SigningMethodRSA
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SigningMethodRS512 *SigningMethodRSA
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)
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func init() {
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// RS256
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SigningMethodRS256 = &SigningMethodRSA{"RS256", crypto.SHA256}
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RegisterSigningMethod(SigningMethodRS256.Alg(), func() SigningMethod {
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return SigningMethodRS256
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})
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// RS384
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SigningMethodRS384 = &SigningMethodRSA{"RS384", crypto.SHA384}
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RegisterSigningMethod(SigningMethodRS384.Alg(), func() SigningMethod {
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return SigningMethodRS384
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})
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// RS512
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SigningMethodRS512 = &SigningMethodRSA{"RS512", crypto.SHA512}
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RegisterSigningMethod(SigningMethodRS512.Alg(), func() SigningMethod {
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return SigningMethodRS512
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})
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}
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func (m *SigningMethodRSA) Alg() string {
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return m.Name
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}
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func (m *SigningMethodRSA) Verify(signingString, signature string, key []byte) error {
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var err error
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// Decode the signature
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var sig []byte
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if sig, err = DecodeSegment(signature); err != nil {
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return err
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}
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// Parse public key
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var rsaKey *rsa.PublicKey
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if rsaKey, err = m.parsePublicKey(key); err != nil {
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return err
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}
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// Create hasher
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hasher := m.Hash.New()
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hasher.Write([]byte(signingString))
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// Verify the signature
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return rsa.VerifyPKCS1v15(rsaKey, m.Hash, hasher.Sum(nil), sig)
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}
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// Implements the Sign method from SigningMethod
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// For this signing method, must be PEM encoded PKCS1 or PKCS8 RSA private key
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func (m *SigningMethodRSA) Sign(signingString string, key []byte) (string, error) {
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var err error
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// Parse private key
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var rsaKey *rsa.PrivateKey
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if rsaKey, err = m.parsePrivateKey(key); err != nil {
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return "", err
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}
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// Create the hasher
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hasher := m.Hash.New()
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hasher.Write([]byte(signingString))
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// Sign the string and return the encoded bytes
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if sigBytes, err := rsa.SignPKCS1v15(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil)); err == nil {
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return EncodeSegment(sigBytes), nil
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} else {
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return "", err
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}
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}
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// Parse PEM encoded PKCS1 or PKCS8 public key
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func (m *SigningMethodRSA) parsePublicKey(key []byte) (*rsa.PublicKey, error) {
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var err error
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// Parse PEM block
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var block *pem.Block
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if block, _ = pem.Decode(key); block == nil {
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return nil, errors.New("Invalid Key: Key must be PEM encoded PKCS1 or PKCS8 private key")
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}
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// Parse the key
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var parsedKey interface{}
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if parsedKey, err = x509.ParsePKIXPublicKey(block.Bytes); err != nil {
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if cert, err := x509.ParseCertificate(block.Bytes); err == nil {
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return nil, err
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} else {
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parsedKey = cert.PublicKey
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}
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}
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var pkey *rsa.PublicKey
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var ok bool
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if pkey, ok = parsedKey.(*rsa.PublicKey); !ok {
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return nil, errors.New("Key is not a valid RSA public key")
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}
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return pkey, nil
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}
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// Parse PEM encoded PKCS1 or PKCS8 private key
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func (m *SigningMethodRSA) parsePrivateKey(key []byte) (*rsa.PrivateKey, error) {
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var err error
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// Parse PEM block
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var block *pem.Block
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if block, _ = pem.Decode(key); block == nil {
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return nil, errors.New("Invalid Key: Key must be PEM encoded PKCS1 or PKCS8 private key")
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}
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var parsedKey interface{}
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if parsedKey, err = x509.ParsePKCS1PrivateKey(block.Bytes); err != nil {
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if parsedKey, err = x509.ParsePKCS8PrivateKey(block.Bytes); err != nil {
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return nil, err
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}
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}
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var pkey *rsa.PrivateKey
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var ok bool
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if pkey, ok = parsedKey.(*rsa.PrivateKey); !ok {
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return nil, errors.New("Key is not a valid RSA private key")
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}
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return pkey, nil
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}
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