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streaming_prf_factory.go
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/
streaming_prf_factory.go
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// Copyright 2022 Google LLC
//
// 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 streamingprf
import (
"errors"
"fmt"
"io"
"github.com/tink-crypto/tink-go/v2/core/primitiveset"
"github.com/tink-crypto/tink-go/v2/keyset"
tinkpb "github.com/tink-crypto/tink-go/v2/proto/tink_go_proto"
)
// New generates a new instance of the Streaming PRF primitive.
func New(h *keyset.Handle) (StreamingPRF, error) {
if h == nil {
return nil, errors.New("keyset handle can't be nil")
}
ps, err := h.PrimitivesWithKeyManager(new(HKDFStreamingPRFKeyManager))
if err != nil {
return nil, fmt.Errorf("streaming_prf_factory: cannot obtain primitive set: %v", err)
}
return newWrappedStreamingPRF(ps)
}
// wrappedStreamingPRF is a Streaming PRF implementation that uses the underlying primitive set for Streaming PRF.
type wrappedStreamingPRF struct {
ps *primitiveset.PrimitiveSet
}
// Asserts that wrappedStreamingPRF implements the StreamingPRF interface.
var _ StreamingPRF = (*wrappedStreamingPRF)(nil)
func newWrappedStreamingPRF(ps *primitiveset.PrimitiveSet) (*wrappedStreamingPRF, error) {
if rawEntries, err := ps.RawEntries(); err != nil || len(rawEntries) != 1 {
return nil, errors.New("streaming_prf_factory: only accepts keysets with 1 RAW key")
}
// ps.Entries is a map of prefix type -> []*Entry.
if len(ps.Entries) != 1 {
return nil, errors.New("streaming_prf_factory: only accepts keys with prefix type RAW")
}
if _, ok := (ps.Primary.Primitive).(StreamingPRF); !ok {
return nil, errors.New("streaming_prf_factory: not a Streaming PRF primitive")
}
if ps.Primary.PrefixType != tinkpb.OutputPrefixType_RAW {
return nil, errors.New("streaming_prf_factory: primary key prefix type is not RAW")
}
if ps.Primary.Status != tinkpb.KeyStatusType_ENABLED {
return nil, errors.New("streaming_prf_factory: primary key is not ENABLED")
}
return &wrappedStreamingPRF{ps: ps}, nil
}
func (w *wrappedStreamingPRF) Compute(input []byte) (io.Reader, error) {
primary := w.ps.Primary
p, ok := (primary.Primitive).(StreamingPRF)
if !ok {
return nil, errors.New("streaming_prf_factory: not a Streaming PRF primitive")
}
return p.Compute(input)
}