62 lines
1.8 KiB
Go
62 lines
1.8 KiB
Go
// Copyright IBM Corp. 2020, 2026
|
|
// SPDX-License-Identifier: BUSL-1.1
|
|
|
|
package crypto
|
|
|
|
import (
|
|
"context"
|
|
"crypto/sha256"
|
|
"fmt"
|
|
"io"
|
|
|
|
wrapping "github.com/hashicorp/go-kms-wrapping/v2"
|
|
"github.com/hashicorp/go-kms-wrapping/v2/aead"
|
|
"github.com/hashicorp/go-kms-wrapping/v2/extras/multi"
|
|
"golang.org/x/crypto/hkdf"
|
|
)
|
|
|
|
// DerivedReader returns a reader from which keys can be read, using the
|
|
// given wrapper, reader length limit, salt and context info. Salt and info can
|
|
// be nil.
|
|
//
|
|
// Example:
|
|
//
|
|
// reader, _ := NewDerivedReader(wrapper, userId, jobId)
|
|
// key := ed25519.GenerateKey(reader)
|
|
func NewDerivedReader(ctx context.Context, wrapper wrapping.Wrapper, lenLimit int64, salt, info []byte) (*io.LimitedReader, error) {
|
|
const op = "crypto.NewDerivedReader"
|
|
if wrapper == nil {
|
|
return nil, fmt.Errorf("%s: missing wrapper: %w", op, ErrInvalidParameter)
|
|
}
|
|
if lenLimit < 20 {
|
|
return nil, fmt.Errorf("%s: lenLimit must be >= 20: %w", op, ErrInvalidParameter)
|
|
}
|
|
var aeadWrapper *aead.Wrapper
|
|
switch w := wrapper.(type) {
|
|
case *multi.PooledWrapper:
|
|
raw := w.WrapperForKeyId("__base__")
|
|
var ok bool
|
|
if aeadWrapper, ok = raw.(*aead.Wrapper); !ok {
|
|
return nil, fmt.Errorf("%s: unexpected wrapper type from multiwrapper base: %w", op, ErrInvalidParameter)
|
|
}
|
|
case *aead.Wrapper:
|
|
aeadWrapper = w
|
|
default:
|
|
return nil, fmt.Errorf("%s: unknown wrapper type: %w", op, ErrInvalidParameter)
|
|
}
|
|
|
|
keyBytes, err := aeadWrapper.KeyBytes(ctx)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("%s: error reading aead key bytes: %w", op, err)
|
|
}
|
|
if keyBytes == nil {
|
|
return nil, fmt.Errorf("%s: aead wrapper missing bytes: %w", op, ErrInvalidParameter)
|
|
}
|
|
|
|
reader := hkdf.New(sha256.New, keyBytes, salt, info)
|
|
return &io.LimitedReader{
|
|
R: reader,
|
|
N: lenLimit,
|
|
}, nil
|
|
}
|