| // Copyright 2018 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 aead |
| |
| import ( |
| "fmt" |
| |
| "github.com/google/tink/go/core/cryptofmt" |
| "github.com/google/tink/go/core/primitiveset" |
| "github.com/google/tink/go/internal/internalregistry" |
| "github.com/google/tink/go/internal/monitoringutil" |
| "github.com/google/tink/go/keyset" |
| "github.com/google/tink/go/monitoring" |
| "github.com/google/tink/go/tink" |
| ) |
| |
| // New returns an AEAD primitive from the given keyset handle. |
| func New(handle *keyset.Handle) (tink.AEAD, error) { |
| ps, err := handle.Primitives() |
| if err != nil { |
| return nil, fmt.Errorf("aead_factory: cannot obtain primitive set: %s", err) |
| } |
| return newWrappedAead(ps) |
| } |
| |
| // wrappedAead is an AEAD implementation that uses the underlying primitive set for encryption |
| // and decryption. |
| type wrappedAead struct { |
| ps *primitiveset.PrimitiveSet |
| encLogger monitoring.Logger |
| decLogger monitoring.Logger |
| } |
| |
| func newWrappedAead(ps *primitiveset.PrimitiveSet) (*wrappedAead, error) { |
| if _, ok := (ps.Primary.Primitive).(tink.AEAD); !ok { |
| return nil, fmt.Errorf("aead_factory: not an AEAD primitive") |
| } |
| |
| for _, primitives := range ps.Entries { |
| for _, p := range primitives { |
| if _, ok := (p.Primitive).(tink.AEAD); !ok { |
| return nil, fmt.Errorf("aead_factory: not an AEAD primitive") |
| } |
| } |
| } |
| encLogger, decLogger, err := createLoggers(ps) |
| if err != nil { |
| return nil, err |
| } |
| return &wrappedAead{ |
| ps: ps, |
| encLogger: encLogger, |
| decLogger: decLogger, |
| }, nil |
| } |
| |
| func createLoggers(ps *primitiveset.PrimitiveSet) (monitoring.Logger, monitoring.Logger, error) { |
| if len(ps.Annotations) == 0 { |
| return &monitoringutil.DoNothingLogger{}, &monitoringutil.DoNothingLogger{}, nil |
| } |
| client := internalregistry.GetMonitoringClient() |
| keysetInfo, err := monitoringutil.KeysetInfoFromPrimitiveSet(ps) |
| if err != nil { |
| return nil, nil, err |
| } |
| encLogger, err := client.NewLogger(&monitoring.Context{ |
| Primitive: "aead", |
| APIFunction: "encrypt", |
| KeysetInfo: keysetInfo, |
| }) |
| if err != nil { |
| return nil, nil, err |
| } |
| decLogger, err := client.NewLogger(&monitoring.Context{ |
| Primitive: "aead", |
| APIFunction: "decrypt", |
| KeysetInfo: keysetInfo, |
| }) |
| if err != nil { |
| return nil, nil, err |
| } |
| return encLogger, decLogger, nil |
| } |
| |
| // Encrypt encrypts the given plaintext with the given associatedData. |
| // It returns the concatenation of the primary's identifier and the ciphertext. |
| func (a *wrappedAead) Encrypt(plaintext, associatedData []byte) ([]byte, error) { |
| primary := a.ps.Primary |
| p, ok := (primary.Primitive).(tink.AEAD) |
| if !ok { |
| return nil, fmt.Errorf("aead_factory: not an AEAD primitive") |
| } |
| ct, err := p.Encrypt(plaintext, associatedData) |
| if err != nil { |
| a.encLogger.LogFailure() |
| return nil, err |
| } |
| a.encLogger.Log(primary.KeyID, len(plaintext)) |
| if len(primary.Prefix) == 0 { |
| return ct, nil |
| } |
| output := make([]byte, 0, len(primary.Prefix)+len(ct)) |
| output = append(output, primary.Prefix...) |
| output = append(output, ct...) |
| return output, nil |
| } |
| |
| // Decrypt decrypts the given ciphertext and authenticates it with the given |
| // associatedData. It returns the corresponding plaintext if the |
| // ciphertext is authenticated. |
| func (a *wrappedAead) Decrypt(ciphertext, associatedData []byte) ([]byte, error) { |
| // try non-raw keys |
| prefixSize := cryptofmt.NonRawPrefixSize |
| if len(ciphertext) > prefixSize { |
| prefix := ciphertext[:prefixSize] |
| ctNoPrefix := ciphertext[prefixSize:] |
| entries, err := a.ps.EntriesForPrefix(string(prefix)) |
| if err == nil { |
| for i := 0; i < len(entries); i++ { |
| p, ok := (entries[i].Primitive).(tink.AEAD) |
| if !ok { |
| return nil, fmt.Errorf("aead_factory: not an AEAD primitive") |
| } |
| |
| pt, err := p.Decrypt(ctNoPrefix, associatedData) |
| if err == nil { |
| a.decLogger.Log(entries[i].KeyID, len(ctNoPrefix)) |
| return pt, nil |
| } |
| } |
| } |
| } |
| // try raw keys |
| entries, err := a.ps.RawEntries() |
| if err == nil { |
| for i := 0; i < len(entries); i++ { |
| p, ok := (entries[i].Primitive).(tink.AEAD) |
| if !ok { |
| return nil, fmt.Errorf("aead_factory: not an AEAD primitive") |
| } |
| |
| pt, err := p.Decrypt(ciphertext, associatedData) |
| if err == nil { |
| a.decLogger.Log(entries[i].KeyID, len(ciphertext)) |
| return pt, nil |
| } |
| } |
| } |
| // nothing worked |
| a.decLogger.LogFailure() |
| return nil, fmt.Errorf("aead_factory: decryption failed") |
| } |