143 lines
3.4 KiB
Go
143 lines
3.4 KiB
Go
// +build go1.4
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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 RSAPSS family of signing methods signing methods
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type SigningMethodRSAPSS struct {
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*SigningMethodRSA
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Options *rsa.PSSOptions
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// VerifyOptions is optional. If set overrides Options for rsa.VerifyPPS.
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// Used to accept tokens signed with rsa.PSSSaltLengthAuto, what doesn't follow
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// https://tools.ietf.org/html/rfc7518#section-3.5 but was used previously.
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// See https://github.com/dgrijalva/jwt-go/issues/285#issuecomment-437451244 for details.
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VerifyOptions *rsa.PSSOptions
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}
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// Specific instances for RS/PS and company.
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var (
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SigningMethodPS256 *SigningMethodRSAPSS
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SigningMethodPS384 *SigningMethodRSAPSS
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SigningMethodPS512 *SigningMethodRSAPSS
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)
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func init() {
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// PS256
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SigningMethodPS256 = &SigningMethodRSAPSS{
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SigningMethodRSA: &SigningMethodRSA{
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Name: "PS256",
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Hash: crypto.SHA256,
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},
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Options: &rsa.PSSOptions{
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SaltLength: rsa.PSSSaltLengthEqualsHash,
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},
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VerifyOptions: &rsa.PSSOptions{
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SaltLength: rsa.PSSSaltLengthAuto,
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},
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}
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RegisterSigningMethod(SigningMethodPS256.Alg(), func() SigningMethod {
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return SigningMethodPS256
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})
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// PS384
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SigningMethodPS384 = &SigningMethodRSAPSS{
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SigningMethodRSA: &SigningMethodRSA{
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Name: "PS384",
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Hash: crypto.SHA384,
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},
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Options: &rsa.PSSOptions{
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SaltLength: rsa.PSSSaltLengthEqualsHash,
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},
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VerifyOptions: &rsa.PSSOptions{
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SaltLength: rsa.PSSSaltLengthAuto,
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},
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}
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RegisterSigningMethod(SigningMethodPS384.Alg(), func() SigningMethod {
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return SigningMethodPS384
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})
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// PS512
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SigningMethodPS512 = &SigningMethodRSAPSS{
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SigningMethodRSA: &SigningMethodRSA{
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Name: "PS512",
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Hash: crypto.SHA512,
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},
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Options: &rsa.PSSOptions{
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SaltLength: rsa.PSSSaltLengthEqualsHash,
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},
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VerifyOptions: &rsa.PSSOptions{
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SaltLength: rsa.PSSSaltLengthAuto,
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},
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}
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RegisterSigningMethod(SigningMethodPS512.Alg(), func() SigningMethod {
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return SigningMethodPS512
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})
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}
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// Implements the Verify method from SigningMethod
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// For this verify method, key must be an rsa.PublicKey struct
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func (m *SigningMethodRSAPSS) 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 *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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opts := m.Options
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if m.VerifyOptions != nil {
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opts = m.VerifyOptions
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}
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return rsa.VerifyPSS(rsaKey, m.Hash, hasher.Sum(nil), sig, opts)
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}
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// Implements the Sign method from SigningMethod
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// For this signing method, key must be an rsa.PrivateKey struct
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func (m *SigningMethodRSAPSS) Sign(signingString string, key interface{}) (string, error) {
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var rsaKey *rsa.PrivateKey
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switch k := key.(type) {
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case *rsa.PrivateKey:
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rsaKey = k
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default:
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return "", ErrInvalidKeyType
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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.SignPSS(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil), m.Options); 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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