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package ciphersuite
import (
"crypto/sha256"
"fmt"
"hash"
"sync/atomic"
"github.com/pion/dtls/v2/pkg/crypto/ciphersuite"
"github.com/pion/dtls/v2/pkg/crypto/clientcertificate"
"github.com/pion/dtls/v2/pkg/crypto/prf"
"github.com/pion/dtls/v2/pkg/protocol/recordlayer"
)
// Aes128Ccm is a base class used by multiple AES-CCM Ciphers
type Aes128Ccm struct {
ccm atomic.Value // *cryptoCCM
clientCertificateType clientcertificate.Type
id ID
psk bool
cryptoCCMTagLen ciphersuite.CCMTagLen
}
func newAes128Ccm(clientCertificateType clientcertificate.Type, id ID, psk bool, cryptoCCMTagLen ciphersuite.CCMTagLen) *Aes128Ccm {
return &Aes128Ccm{
clientCertificateType: clientCertificateType,
id: id,
psk: psk,
cryptoCCMTagLen: cryptoCCMTagLen,
}
}
// CertificateType returns what type of certificate this CipherSuite exchanges
func (c *Aes128Ccm) CertificateType() clientcertificate.Type {
return c.clientCertificateType
}
// ID returns the ID of the CipherSuite
func (c *Aes128Ccm) ID() ID {
return c.id
}
func (c *Aes128Ccm) String() string {
return c.id.String()
}
// HashFunc returns the hashing func for this CipherSuite
func (c *Aes128Ccm) HashFunc() func() hash.Hash {
return sha256.New
}
// AuthenticationType controls what authentication method is using during the handshake
func (c *Aes128Ccm) AuthenticationType() AuthenticationType {
if c.psk {
return AuthenticationTypePreSharedKey
}
return AuthenticationTypeCertificate
}
// IsInitialized returns if the CipherSuite has keying material and can
// encrypt/decrypt packets
func (c *Aes128Ccm) IsInitialized() bool {
return c.ccm.Load() != nil
}
// Init initializes the internal Cipher with keying material
func (c *Aes128Ccm) Init(masterSecret, clientRandom, serverRandom []byte, isClient bool) error {
const (
prfMacLen = 0
prfKeyLen = 16
prfIvLen = 4
)
keys, err := prf.GenerateEncryptionKeys(masterSecret, clientRandom, serverRandom, prfMacLen, prfKeyLen, prfIvLen, c.HashFunc())
if err != nil {
return err
}
var ccm *ciphersuite.CCM
if isClient {
ccm, err = ciphersuite.NewCCM(c.cryptoCCMTagLen, keys.ClientWriteKey, keys.ClientWriteIV, keys.ServerWriteKey, keys.ServerWriteIV)
} else {
ccm, err = ciphersuite.NewCCM(c.cryptoCCMTagLen, keys.ServerWriteKey, keys.ServerWriteIV, keys.ClientWriteKey, keys.ClientWriteIV)
}
c.ccm.Store(ccm)
return err
}
// Encrypt encrypts a single TLS RecordLayer
func (c *Aes128Ccm) Encrypt(pkt *recordlayer.RecordLayer, raw []byte) ([]byte, error) {
ccm := c.ccm.Load()
if ccm == nil {
return nil, fmt.Errorf("%w, unable to encrypt", errCipherSuiteNotInit)
}
return ccm.(*ciphersuite.CCM).Encrypt(pkt, raw)
}
// Decrypt decrypts a single TLS RecordLayer
func (c *Aes128Ccm) Decrypt(raw []byte) ([]byte, error) {
ccm := c.ccm.Load()
if ccm == nil {
return nil, fmt.Errorf("%w, unable to decrypt", errCipherSuiteNotInit)
}
return ccm.(*ciphersuite.CCM).Decrypt(raw)
}
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