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package jose
import (
"crypto/rand"
"crypto/rsa"
"errors"
)
func init() {
RegisterJws(&RsaUsingSha{keySizeBits: 256})
RegisterJws(&RsaUsingSha{keySizeBits: 384})
RegisterJws(&RsaUsingSha{keySizeBits: 512})
}
// RSA using SHA signature algorithm implementation
type RsaUsingSha struct{
keySizeBits int
}
func (alg *RsaUsingSha) Name() string {
switch alg.keySizeBits {
case 256: return RS256
case 384: return RS384
default: return RS512
}
}
func (alg *RsaUsingSha) Verify(securedInput, signature []byte, key interface{}) error {
if pubKey,ok:=key.(*rsa.PublicKey);ok {
return rsa.VerifyPKCS1v15(pubKey, hashFunc(alg.keySizeBits), sha(alg.keySizeBits, securedInput), signature)
}
return errors.New("RsaUsingSha.Verify(): expects key to be '*rsa.PublicKey'")
}
func (alg *RsaUsingSha) Sign(securedInput []byte, key interface{}) (signature []byte, err error) {
if privKey,ok:=key.(*rsa.PrivateKey);ok {
return rsa.SignPKCS1v15(rand.Reader, privKey, hashFunc(alg.keySizeBits), sha(alg.keySizeBits, securedInput))
}
return nil,errors.New("RsaUsingSha.Sign(): expects key to be '*rsa.PrivateKey'")
}
func sha(keySizeBits int, input []byte) (hash []byte) {
hasher := hashAlg(keySizeBits)
hasher.Write(input)
return hasher.Sum(nil)
}
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