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@dgrijalva @simonjefford @martinlindhe
102 lines (83 sloc) 2.38 KB
package jwt
import (
"crypto"
"crypto/rand"
"crypto/rsa"
)
// Implements the RSA family of signing methods signing methods
// Expects *rsa.PrivateKey for signing and *rsa.PublicKey for validation
type SigningMethodRSA struct {
Name string
Hash crypto.Hash
}
// Specific instances for RS256 and company
var (
SigningMethodRS256 *SigningMethodRSA
SigningMethodRS384 *SigningMethodRSA
SigningMethodRS512 *SigningMethodRSA
)
func init() {
// RS256
SigningMethodRS256 = &SigningMethodRSA{"RS256", crypto.SHA256}
RegisterSigningMethod(SigningMethodRS256.Alg(), func() SigningMethod {
return SigningMethodRS256
})
// RS384
SigningMethodRS384 = &SigningMethodRSA{"RS384", crypto.SHA384}
RegisterSigningMethod(SigningMethodRS384.Alg(), func() SigningMethod {
return SigningMethodRS384
})
// RS512
SigningMethodRS512 = &SigningMethodRSA{"RS512", crypto.SHA512}
RegisterSigningMethod(SigningMethodRS512.Alg(), func() SigningMethod {
return SigningMethodRS512
})
}
func (m *SigningMethodRSA) Alg() string {
return m.Name
}
// Implements the Verify method from SigningMethod
// For this signing method, must be an *rsa.PublicKey structure.
func (m *SigningMethodRSA) Verify(signingString, signature string, key interface{}) error {
var err error
// Decode the signature
var sig []byte
if sig, err = DecodeSegment(signature); err != nil {
return err
}
var rsaKey *rsa.PublicKey
var ok bool
if rsaKey, ok = key.(*rsa.PublicKey); !ok {
return ErrInvalidKeyType
}
// Create hasher
if !m.Hash.Available() {
return ErrHashUnavailable
}
hasher := m.Hash.New()
hasher.Write([]byte(signingString))
// Verify the signature
return rsa.VerifyPKCS1v15(rsaKey, m.Hash, hasher.Sum(nil), sig)
}
// Implements the Sign method from SigningMethod
// For this signing method, must be an *rsa.PrivateKey structure.
func (m *SigningMethodRSA) Sign(signingString string, key interface{}) (string, error) {
var rsaKey *rsa.PrivateKey
var ok bool
// Validate type of key
if rsaKey, ok = key.(*rsa.PrivateKey); !ok {
return "", ErrInvalidKey
}
// Create the hasher
if !m.Hash.Available() {
return "", ErrHashUnavailable
}
hasher := m.Hash.New()
hasher.Write([]byte(signingString))
// Sign the string and return the encoded bytes
if sigBytes, err := rsa.SignPKCS1v15(rand.Reader, rsaKey, m.Hash, hasher.Sum(nil)); err == nil {
return EncodeSegment(sigBytes), nil
} else {
return "", err
}
}
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