Implement a "magic wormhole" file-sharing solution

1 files changed, 0 insertions, 139 deletions

diff --git a/internal/cryptoutil/cryptoutil.go b/internal/cryptoutil/cryptoutil.go
deleted file mode 100644
index 0429b02..0000000
--- a/internal/cryptoutil/cryptoutil.go
+++ /dev/null
@@ -1,139 +0,0 @@
-// Package cryptoutil contains friendly wrappers around the algorithms from the
-// standard library's crypto package.
-package cryptoutil
-
-import (
-	"crypto/hkdf"
-	"crypto/hmac"
-	"crypto/pbkdf2"
-	"crypto/rand"
-	"crypto/sha512"
-	"crypto/subtle"
-	"encoding/binary"
-	"encoding/hex"
-	"errors"
-	"io"
-)
-
-const (
-	defaultIterations = 4718580 // from cmd/finditers
-
-	oneSaltSize = 64
-	hashSize    = 64
-	certSize    = sha512.Size
-)
-
-// SaltSize is the expected salt length for HashIter.
-const SaltSize = 2 * oneSaltSize
-
-// A PasswordHash must be PasswordHashSize bytes.
-const PasswordHashSize = SaltSize + hashSize
-
-// A PasswordHash is derived from the user's password and can be passed to
-// CheckPassword to verify if two passwords match. A PasswordHash must be
-// PasswordHashSize bytes.
-type PasswordHash []byte
-
-func (h PasswordHash) String() string { return hex.EncodeToString(h) }
-
-// A RawKey is generated from a password hash and can be used to derive further
-// key material.
-type RawKey struct {
-	key []byte
-}
-
-// An HMACKey must be HMACKeySize bytes.
-const HMACKeySize = sha512.BlockSize
-
-// An HMAC key can be used to symmetrically sign and verify messages
-// using HMAC-SHA512. An HMACKey must be HMACKeyLen bytes.
-type HMACKey []byte
-
-// A SignedMessage is a message that has been cryptographically signed
-// with HMAC-SHA512.
-type SignedMessage []byte
-
-// An EncryptedMessage is encrypted with AES-256-CTR-HMAC-SHA512.
-type EncryptedMessage []byte
-
-// HashIter runs PBKDF2-SHA512 for iter iterations. Useful for benchmarking. The
-// salt must be SaltSize bytes.
-func HashIter(password string, salt []byte, iter int) ([]byte, error) {
-	return pbkdf2.Key(sha512.New, password, salt, iter, sha512.Size)
-}
-
-func hashWithSalt(password string, salt []byte) (RawKey, []byte, error) {
-	hash, err := HashIter(password, salt[:oneSaltSize], defaultIterations)
-	if err != nil {
-		return RawKey{}, nil, err
-	}
-	key, err := hkdf.Extract(sha512.New, hash, salt[oneSaltSize:])
-	if err != nil {
-		return RawKey{}, nil, err
-	}
-	pwHash, err := hkdf.Expand(sha512.New, key, "pwhash", hashSize)
-	if err != nil {
-		return RawKey{}, nil, err
-	}
-	return RawKey{key}, pwHash, nil
-}
-
-// Hash hashes a user password using PBKDF2-SHA512.
-func Hash(password string) (PasswordHash, error) {
-	salt := make([]byte, SaltSize, SaltSize+hashSize)
-	rand.Read(salt)
-	_, pwHash, err := hashWithSalt(password, salt)
-	if err != nil {
-		return nil, err
-	}
-	return append(salt, pwHash...), nil
-}
-
-// CheckPassword verifies password against a PasswordHash and returns an
-// EncryptionKey derived from the password if successful.
-func (h PasswordHash) CheckPassword(password string) (RawKey, error) {
-	salt, expectedHash := h[:SaltSize], h[SaltSize:]
-	key, pwHash, err := hashWithSalt(password, salt)
-	if err != nil {
-		return RawKey{}, err
-	}
-	if subtle.ConstantTimeCompare(pwHash, expectedHash) == 0 {
-		return RawKey{}, errors.New("incorrect password")
-	}
-	return key, nil
-}
-
-func (k HMACKey) mac(out, msg []byte, info string) []byte {
-	mac := hmac.New(sha512.New, k)
-	buf := make([]byte, 0, binary.MaxVarintLen64)
-	mac.Write(binary.AppendUvarint(buf, uint64(len(info))))
-	io.WriteString(mac, info)
-	mac.Write(msg)
-	return mac.Sum(out)
-}
-
-// Sign generates an HMAC-SHA512 signature and appends it to msg. The info and
-// additionalData are also authenticated, but are not included in the returned
-// signed message.
-func (k HMACKey) Sign(msg []byte, info string) SignedMessage {
-	return k.mac(msg, msg, info)
-}
-
-// Verify checks whether the given message has a valid signature, and returns
-// the raw message if it does. The additionalData must match the data passed
-// to Sign.
-func (k HMACKey) Verify(msg SignedMessage, info string) ([]byte, bool) {
-	if len(msg) < certSize {
-		return nil, false
-	}
-	msg, sig := msg[:len(msg)-certSize], msg[len(msg)-certSize:]
-	if !hmac.Equal(sig, k.mac(nil, msg, info)) {
-		return nil, false
-	}
-	return msg, true
-}
-
-// EncryptionKey derives an EncryptionKey.
-func (k RawKey) EncryptionKey() (EncryptionKey, error) {
-	return hkdf.Expand(sha512.New, k.key, "encrypt", sha512.Size)
-}