115 lines
2.6 KiB
Go
115 lines
2.6 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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)
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// Implements the RSA family of signing methods signing methods
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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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// Specific instances for RS256 and company
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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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// Implements the Verify method from SigningMethod
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// For this signing method, must be either a PEM encoded PKCS1 or PKCS8 RSA public key as
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// []byte, or an rsa.PublicKey structure.
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func (m *SigningMethodRSA) Verify(signingString, signature string, key interface{}) 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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var rsaKey *rsa.PublicKey
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switch k := key.(type) {
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case []byte:
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if rsaKey, err = ParseRSAPublicKeyFromPEM(k); err != nil {
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return err
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}
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case *rsa.PublicKey:
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rsaKey = k
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default:
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return ErrInvalidKey
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}
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// Create hasher
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if !m.Hash.Available() {
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return ErrHashUnavailable
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}
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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 either a PEM encoded PKCS1 or PKCS8 RSA private key as
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// []byte, or an rsa.PrivateKey structure.
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func (m *SigningMethodRSA) Sign(signingString string, key interface{}) (string, error) {
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var err error
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var rsaKey *rsa.PrivateKey
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switch k := key.(type) {
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case []byte:
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if rsaKey, err = ParseRSAPrivateKeyFromPEM(k); err != nil {
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return "", err
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}
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case *rsa.PrivateKey:
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rsaKey = k
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default:
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return "", ErrInvalidKey
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}
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// Create the hasher
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if !m.Hash.Available() {
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return "", ErrHashUnavailable
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}
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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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