gitea/vendor/github.com/golang-jwt/jwt/ecdsa_go1.15.go

55 lines
1.3 KiB
Go

//+build go1.15
package jwt
import (
"crypto/ecdsa"
"crypto/rand"
)
// Implements the Sign method from SigningMethod
// For this signing method, key must be an ecdsa.PrivateKey struct
func (m *SigningMethodECDSA) Sign(signingString string, key interface{}) (string, error) {
// Get the key
var ecdsaKey *ecdsa.PrivateKey
switch k := key.(type) {
case *ecdsa.PrivateKey:
ecdsaKey = k
default:
return "", ErrInvalidKeyType
}
// Create the hasher
if !m.Hash.Available() {
return "", ErrHashUnavailable
}
hasher := m.Hash.New()
hasher.Write([]byte(signingString))
// Sign the string and return r, s
if r, s, err := ecdsa.Sign(rand.Reader, ecdsaKey, hasher.Sum(nil)); err == nil {
curveBits := ecdsaKey.Curve.Params().BitSize
if m.CurveBits != curveBits {
return "", ErrInvalidKey
}
keyBytes := curveBits / 8
if curveBits%8 > 0 {
keyBytes += 1
}
// We serialize the outputs (r and s) into big-endian byte arrays
// padded with zeros on the left to make sure the sizes work out.
// Output must be 2*keyBytes long.
out := make([]byte, 2*keyBytes)
r.FillBytes(out[0:keyBytes]) // r is assigned to the first half of output.
s.FillBytes(out[keyBytes:]) // s is assigned to the second half of output.
return EncodeSegment(out), nil
} else {
return "", err
}
}