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/*
* Minio Go Library for Amazon S3 Compatible Cloud Storage
* Copyright 2018 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package encrypt
import (
"crypto/md5"
"encoding/base64"
"encoding/json"
"errors"
"net/http"
"golang.org/x/crypto/argon2"
)
const (
// sseGenericHeader is the AWS SSE header used for SSE-S3 and SSE-KMS.
sseGenericHeader = "X-Amz-Server-Side-Encryption"
// sseKmsKeyID is the AWS SSE-KMS key id.
sseKmsKeyID = sseGenericHeader + "-Aws-Kms-Key-Id"
// sseEncryptionContext is the AWS SSE-KMS Encryption Context data.
sseEncryptionContext = sseGenericHeader + "-Encryption-Context"
// sseCustomerAlgorithm is the AWS SSE-C algorithm HTTP header key.
sseCustomerAlgorithm = sseGenericHeader + "-Customer-Algorithm"
// sseCustomerKey is the AWS SSE-C encryption key HTTP header key.
sseCustomerKey = sseGenericHeader + "-Customer-Key"
// sseCustomerKeyMD5 is the AWS SSE-C encryption key MD5 HTTP header key.
sseCustomerKeyMD5 = sseGenericHeader + "-Customer-Key-MD5"
// sseCopyCustomerAlgorithm is the AWS SSE-C algorithm HTTP header key for CopyObject API.
sseCopyCustomerAlgorithm = "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm"
// sseCopyCustomerKey is the AWS SSE-C encryption key HTTP header key for CopyObject API.
sseCopyCustomerKey = "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key"
// sseCopyCustomerKeyMD5 is the AWS SSE-C encryption key MD5 HTTP header key for CopyObject API.
sseCopyCustomerKeyMD5 = "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-MD5"
)
// PBKDF creates a SSE-C key from the provided password and salt.
// PBKDF is a password-based key derivation function
// which can be used to derive a high-entropy cryptographic
// key from a low-entropy password and a salt.
type PBKDF func(password, salt []byte) ServerSide
// DefaultPBKDF is the default PBKDF. It uses Argon2id with the
// recommended parameters from the RFC draft (1 pass, 64 MB memory, 4 threads).
var DefaultPBKDF PBKDF = func(password, salt []byte) ServerSide {
sse := ssec{}
copy(sse[:], argon2.IDKey(password, salt, 1, 64*1024, 4, 32))
return sse
}
// Type is the server-side-encryption method. It represents one of
// the following encryption methods:
// - SSE-C: server-side-encryption with customer provided keys
// - KMS: server-side-encryption with managed keys
// - S3: server-side-encryption using S3 storage encryption
type Type string
const (
// SSEC represents server-side-encryption with customer provided keys
SSEC Type = "SSE-C"
// KMS represents server-side-encryption with managed keys
KMS Type = "KMS"
// S3 represents server-side-encryption using S3 storage encryption
S3 Type = "S3"
)
// ServerSide is a form of S3 server-side-encryption.
type ServerSide interface {
// Type returns the server-side-encryption method.
Type() Type
// Marshal adds encryption headers to the provided HTTP headers.
// It marks an HTTP request as server-side-encryption request
// and inserts the required data into the headers.
Marshal(h http.Header)
}
// NewSSE returns a server-side-encryption using S3 storage encryption.
// Using SSE-S3 the server will encrypt the object with server-managed keys.
func NewSSE() ServerSide { return s3{} }
// NewSSEKMS returns a new server-side-encryption using SSE-KMS and the provided Key Id and context.
func NewSSEKMS(keyID string, context interface{}) (ServerSide, error) {
if context == nil {
return kms{key: keyID, hasContext: false}, nil
}
serializedContext, err := json.Marshal(context)
if err != nil {
return nil, err
}
return kms{key: keyID, context: serializedContext, hasContext: true}, nil
}
// NewSSEC returns a new server-side-encryption using SSE-C and the provided key.
// The key must be 32 bytes long.
func NewSSEC(key []byte) (ServerSide, error) {
if len(key) != 32 {
return nil, errors.New("encrypt: SSE-C key must be 256 bit long")
}
sse := ssec{}
copy(sse[:], key)
return sse, nil
}
// SSE transforms a SSE-C copy encryption into a SSE-C encryption.
// It is the inverse of SSECopy(...).
//
// If the provided sse is no SSE-C copy encryption SSE returns
// sse unmodified.
func SSE(sse ServerSide) ServerSide {
if sse == nil || sse.Type() != SSEC {
return sse
}
if sse, ok := sse.(ssecCopy); ok {
return ssec(sse)
}
return sse
}
// SSECopy transforms a SSE-C encryption into a SSE-C copy
// encryption. This is required for SSE-C key rotation or a SSE-C
// copy where the source and the destination should be encrypted.
//
// If the provided sse is no SSE-C encryption SSECopy returns
// sse unmodified.
func SSECopy(sse ServerSide) ServerSide {
if sse == nil || sse.Type() != SSEC {
return sse
}
if sse, ok := sse.(ssec); ok {
return ssecCopy(sse)
}
return sse
}
type ssec [32]byte
func (s ssec) Type() Type { return SSEC }
func (s ssec) Marshal(h http.Header) {
keyMD5 := md5.Sum(s[:])
h.Set(sseCustomerAlgorithm, "AES256")
h.Set(sseCustomerKey, base64.StdEncoding.EncodeToString(s[:]))
h.Set(sseCustomerKeyMD5, base64.StdEncoding.EncodeToString(keyMD5[:]))
}
type ssecCopy [32]byte
func (s ssecCopy) Type() Type { return SSEC }
func (s ssecCopy) Marshal(h http.Header) {
keyMD5 := md5.Sum(s[:])
h.Set(sseCopyCustomerAlgorithm, "AES256")
h.Set(sseCopyCustomerKey, base64.StdEncoding.EncodeToString(s[:]))
h.Set(sseCopyCustomerKeyMD5, base64.StdEncoding.EncodeToString(keyMD5[:]))
}
type s3 struct{}
func (s s3) Type() Type { return S3 }
func (s s3) Marshal(h http.Header) { h.Set(sseGenericHeader, "AES256") }
type kms struct {
key string
context []byte
hasContext bool
}
func (s kms) Type() Type { return KMS }
func (s kms) Marshal(h http.Header) {
h.Set(sseGenericHeader, "aws:kms")
h.Set(sseKmsKeyID, s.key)
if s.hasContext {
h.Set(sseEncryptionContext, base64.StdEncoding.EncodeToString(s.context))
}
}
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