rename all remaining packages to internal/ (#12418)

This is to ensure that there are no projects
that try to import `minio/minio/pkg` into
their own repo. Any such common packages should
go to `https://github.com/minio/pkg`

internal/crypto/key.go

@@ -0,0 +1,179 @@
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package crypto
+
+import (
+	"bytes"
+	"context"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/binary"
+	"errors"
+	"io"
+	"path"
+
+	"github.com/minio/minio/internal/fips"
+	"github.com/minio/minio/internal/logger"
+	"github.com/minio/sio"
+)
+
+// ObjectKey is a 256 bit secret key used to encrypt the object.
+// It must never be stored in plaintext.
+type ObjectKey [32]byte
+
+// GenerateKey generates a unique ObjectKey from a 256 bit external key
+// and a source of randomness. If random is nil the default PRNG of the
+// system (crypto/rand) is used.
+func GenerateKey(extKey []byte, random io.Reader) (key ObjectKey) {
+	if random == nil {
+		random = rand.Reader
+	}
+	if len(extKey) != 32 { // safety check
+		logger.CriticalIf(context.Background(), errors.New("crypto: invalid key length"))
+	}
+	var nonce [32]byte
+	if _, err := io.ReadFull(random, nonce[:]); err != nil {
+		logger.CriticalIf(context.Background(), errOutOfEntropy)
+	}
+	sha := sha256.New()
+	sha.Write(extKey)
+	sha.Write(nonce[:])
+	sha.Sum(key[:0])
+	return key
+}
+
+// GenerateIV generates a new random 256 bit IV from the provided source
+// of randomness. If random is nil the default PRNG of the system
+// (crypto/rand) is used.
+func GenerateIV(random io.Reader) (iv [32]byte) {
+	if random == nil {
+		random = rand.Reader
+	}
+	if _, err := io.ReadFull(random, iv[:]); err != nil {
+		logger.CriticalIf(context.Background(), errOutOfEntropy)
+	}
+	return iv
+}
+
+// SealedKey represents a sealed object key. It can be stored
+// at an untrusted location.
+type SealedKey struct {
+	Key       [64]byte // The encrypted and authenticted object-key.
+	IV        [32]byte // The random IV used to encrypt the object-key.
+	Algorithm string   // The sealing algorithm used to encrypt the object key.
+}
+
+// Seal encrypts the ObjectKey using the 256 bit external key and IV. The sealed
+// key is also cryptographically bound to the object's path (bucket/object) and the
+// domain (SSE-C or SSE-S3).
+func (key ObjectKey) Seal(extKey []byte, iv [32]byte, domain, bucket, object string) SealedKey {
+	if len(extKey) != 32 {
+		logger.CriticalIf(context.Background(), errors.New("crypto: invalid key length"))
+	}
+	var (
+		sealingKey   [32]byte
+		encryptedKey bytes.Buffer
+	)
+	mac := hmac.New(sha256.New, extKey[:])
+	mac.Write(iv[:])
+	mac.Write([]byte(domain))
+	mac.Write([]byte(SealAlgorithm))
+	mac.Write([]byte(path.Join(bucket, object))) // use path.Join for canonical 'bucket/object'
+	mac.Sum(sealingKey[:0])
+	if n, err := sio.Encrypt(&encryptedKey, bytes.NewReader(key[:]), sio.Config{Key: sealingKey[:], CipherSuites: fips.CipherSuitesDARE()}); n != 64 || err != nil {
+		logger.CriticalIf(context.Background(), errors.New("Unable to generate sealed key"))
+	}
+	sealedKey := SealedKey{
+		IV:        iv,
+		Algorithm: SealAlgorithm,
+	}
+	copy(sealedKey.Key[:], encryptedKey.Bytes())
+	return sealedKey
+}
+
+// Unseal decrypts a sealed key using the 256 bit external key. Since the sealed key
+// may be cryptographically bound to the object's path the same bucket/object as during sealing
+// must be provided. On success the ObjectKey contains the decrypted sealed key.
+func (key *ObjectKey) Unseal(extKey []byte, sealedKey SealedKey, domain, bucket, object string) error {
+	var (
+		unsealConfig sio.Config
+	)
+	switch sealedKey.Algorithm {
+	default:
+		return Errorf("The sealing algorithm '%s' is not supported", sealedKey.Algorithm)
+	case SealAlgorithm:
+		mac := hmac.New(sha256.New, extKey[:])
+		mac.Write(sealedKey.IV[:])
+		mac.Write([]byte(domain))
+		mac.Write([]byte(SealAlgorithm))
+		mac.Write([]byte(path.Join(bucket, object))) // use path.Join for canonical 'bucket/object'
+		unsealConfig = sio.Config{MinVersion: sio.Version20, Key: mac.Sum(nil), CipherSuites: fips.CipherSuitesDARE()}
+	case InsecureSealAlgorithm:
+		sha := sha256.New()
+		sha.Write(extKey[:])
+		sha.Write(sealedKey.IV[:])
+		unsealConfig = sio.Config{MinVersion: sio.Version10, Key: sha.Sum(nil), CipherSuites: fips.CipherSuitesDARE()}
+	}
+
+	if out, err := sio.DecryptBuffer(key[:0], sealedKey.Key[:], unsealConfig); len(out) != 32 || err != nil {
+		return ErrSecretKeyMismatch
+	}
+	return nil
+}
+
+// DerivePartKey derives an unique 256 bit key from an ObjectKey and the part index.
+func (key ObjectKey) DerivePartKey(id uint32) (partKey [32]byte) {
+	var bin [4]byte
+	binary.LittleEndian.PutUint32(bin[:], id)
+
+	mac := hmac.New(sha256.New, key[:])
+	mac.Write(bin[:])
+	mac.Sum(partKey[:0])
+	return partKey
+}
+
+// SealETag seals the etag using the object key.
+// It does not encrypt empty ETags because such ETags indicate
+// that the S3 client hasn't sent an ETag = MD5(object) and
+// the backend can pick an ETag value.
+func (key ObjectKey) SealETag(etag []byte) []byte {
+	if len(etag) == 0 { // don't encrypt empty ETag - only if client sent ETag = MD5(object)
+		return etag
+	}
+	var buffer bytes.Buffer
+	mac := hmac.New(sha256.New, key[:])
+	mac.Write([]byte("SSE-etag"))
+	if _, err := sio.Encrypt(&buffer, bytes.NewReader(etag), sio.Config{Key: mac.Sum(nil), CipherSuites: fips.CipherSuitesDARE()}); err != nil {
+		logger.CriticalIf(context.Background(), errors.New("Unable to encrypt ETag using object key"))
+	}
+	return buffer.Bytes()
+}
+
+// UnsealETag unseals the etag using the provided object key.
+// It does not try to decrypt the ETag if len(etag) == 16
+// because such ETags indicate that the S3 client hasn't sent
+// an ETag = MD5(object) and the backend has picked an ETag value.
+func (key ObjectKey) UnsealETag(etag []byte) ([]byte, error) {
+	if !IsETagSealed(etag) {
+		return etag, nil
+	}
+	mac := hmac.New(sha256.New, key[:])
+	mac.Write([]byte("SSE-etag"))
+	return sio.DecryptBuffer(make([]byte, 0, len(etag)), etag, sio.Config{Key: mac.Sum(nil), CipherSuites: fips.CipherSuitesDARE()})
+}