func pkcs1v15HashInfo(hash crypto.Hash, inLen int) (hashLen int, prefix []byte, err error) {
hashLen = hash.Size()
if inLen != hashLen {
return 0, nil, errors.New("input must be hashed message")
}
prefix, ok := hashPrefixes[hash]
if !ok {
return 0, nil, errors.New("unsupported hash function")
}
return
}
// EncodeDigest encodes a hash algorithm and a digest to be put in an assertion header.
func EncodeDigest(hash crypto.Hash, hashDigest []byte) (string, error) {
algo := ""
switch hash {
case crypto.SHA256:
algo = "sha256"
default:
return "", fmt.Errorf("unsupported hash")
}
if len(hashDigest) != hash.Size() {
return "", fmt.Errorf("hash digest by %s should be %d bytes", algo, hash.Size())
}
return fmt.Sprintf("%s %s", algo, base64.RawURLEncoding.EncodeToString(hashDigest)), nil
}
// SignPSS calculates the signature of hashed using RSASSA-PSS [1].
// Note that hashed must be the result of hashing the input message using the
// given hash funcion. The opts argument may be nil, in which case sensible
// defaults are used.
func SignPSS(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte, opts *PSSOptions) (s []byte, err error) {
saltLength := opts.saltLength()
switch saltLength {
case PSSSaltLengthAuto:
saltLength = (priv.N.BitLen()+7)/8 - 2 - hash.Size()
case PSSSaltLengthEqualsHash:
saltLength = hash.Size()
}
salt := make([]byte, saltLength)
if _, err = io.ReadFull(rand, salt); err != nil {
return
}
return signPSSWithSalt(rand, priv, hash, hashed, salt)
}
func checkDigest(headers map[string]interface{}, name string, h crypto.Hash) ([]byte, error) {
digestStr, err := checkNotEmptyString(headers, name)
if err != nil {
return nil, err
}
b, err := base64.RawURLEncoding.DecodeString(digestStr)
if err != nil {
return nil, fmt.Errorf("%q header cannot be decoded: %v", name, err)
}
if len(b) != h.Size() {
return nil, fmt.Errorf("%q header does not have the expected bit length: %d", name, len(b)*8)
}
return b, nil
}
func (h Hash) Validate() report.Report {
var hash crypto.Hash
switch h.Function {
case "sha512":
hash = crypto.SHA512
default:
return report.ReportFromError(ErrHashUnrecognized, report.EntryError)
}
if len(h.Sum) != hex.EncodedLen(hash.Size()) {
return report.ReportFromError(ErrHashWrongSize, report.EntryError)
}
return report.Report{}
}
func (h Hash) AssertValid() error {
var hash crypto.Hash
switch h.Function {
case "sha512":
hash = crypto.SHA512
default:
return ErrHashUnrecognized
}
if len(h.Sum) != hex.EncodedLen(hash.Size()) {
return ErrHashWrongSize
}
return nil
}
func pkcs1v15HashInfo(hash crypto.Hash, inLen int) (hashLen int, prefix []byte, err error) {
// Special case: crypto.Hash(0) is used to indicate that the data is
// signed directly.
if hash == 0 {
return inLen, nil, nil
}
hashLen = hash.Size()
if inLen != hashLen {
return 0, nil, errors.New("crypto/rsa: input must be hashed message")
}
prefix, ok := hashPrefixes[hash]
if !ok {
return 0, nil, errors.New("crypto/rsa: unsupported hash function")
}
return
}
func ssl30MAC(hash crypto.Hash, key, input, ad []byte) []byte {
padLength := 48
if hash.Size() == 20 {
padLength = 40
}
h := hash.New()
h.Write(key)
h.Write(ssl30Pad1[:padLength])
h.Write(ad)
h.Write(input)
digestBuf := h.Sum(nil)
h.Reset()
h.Write(key)
h.Write(ssl30Pad2[:padLength])
h.Write(digestBuf)
return h.Sum(digestBuf[:0])
}
// This function creates a new TOTP object
// This is the function which is needed to start the whole process
// account: usually the user email
// issuer: the name of the company/service
// hash: is the crypto function used: crypto.SHA1, crypto.SHA256, crypto.SHA512
// digits: is the token amount of digits (6 or 7 or 8)
// steps: the amount of second the token is valid
// it autmatically generates a secret key using the golang crypto rand package. If there is not enough entropy the function returns an error
// The key is not encrypted in this package. It's a secret key. Therefore if you transfer the key bytes in the network,
// please take care of protecting the key or in fact all the bytes.
func NewTOTP(account, issuer string, hash crypto.Hash, digits int) (*Totp, error) {
keySize := hash.Size()
key := make([]byte, keySize)
total, err := rand.Read(key)
if err != nil {
return nil, errors.New(fmt.Sprintf("TOTP failed to create because there is not enough entropy, we got only %d random bytes", total))
}
// sanitize the digits range otherwise it may create invalid tokens !
if digits < 6 || digits > 8 {
digits = 8
}
return makeTOTP(key, account, issuer, hash, digits)
}
// verifyPSS verifies a PSS signature with the given salt length.
func verifyPSS(pub *PublicKey, hash crypto.Hash, hashed []byte, sig []byte, saltLen int) error {
nBits := pub.N.BitLen()
if len(sig) != (nBits+7)/8 {
return ErrVerification
}
s := new(big.Int).SetBytes(sig)
m := encrypt(new(big.Int), pub, s)
emBits := nBits - 1
emLen := (emBits + 7) / 8
if emLen < len(m.Bytes()) {
return ErrVerification
}
em := make([]byte, emLen)
copyWithLeftPad(em, m.Bytes())
if saltLen == PSSSaltLengthEqualsHash {
saltLen = hash.Size()
}
return emsaPSSVerify(hashed, em, emBits, saltLen, hash.New())
}
