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Small refactoring of record encryption code

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This commit is contained in:
Henry Case 2018-08-10 20:48:54 +01:00
parent ad86d61c42
commit 1782162852
1 changed files with 12 additions and 11 deletions
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23
conn.go
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@ -472,12 +472,6 @@ func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) {
case aead: case aead:
// explicitIVLen is always 0 for TLS1.3 // explicitIVLen is always 0 for TLS1.3
payloadLen := len(b.data) - recordHeaderLen - explicitIVLen payloadLen := len(b.data) - recordHeaderLen - explicitIVLen
overhead := c.Overhead()
if hc.version >= VersionTLS13 {
overhead++ // TODO(kk): why this is done?
}
b.resize(len(b.data) + overhead)
nonce := b.data[recordHeaderLen : recordHeaderLen+explicitIVLen] nonce := b.data[recordHeaderLen : recordHeaderLen+explicitIVLen]
if len(nonce) == 0 { if len(nonce) == 0 {
nonce = hc.seq[:] nonce = hc.seq[:]
@ -491,17 +485,24 @@ func (hc *halfConn) encrypt(b *block, explicitIVLen int) (bool, alert) {
copy(hc.additionalData[8:], b.data[:3]) copy(hc.additionalData[8:], b.data[:3])
binary.BigEndian.PutUint16(hc.additionalData[11:], uint16(payloadLen)) binary.BigEndian.PutUint16(hc.additionalData[11:], uint16(payloadLen))
additionalData = hc.additionalData[:] additionalData = hc.additionalData[:]
b.resize(len(b.data) + c.Overhead())
} else { } else {
// opaque type // In TLS1.3 1 byte of content type is encrypted
payload = payload[:len(payload)+1] innerPlaintextLen := payloadLen + 1
payload[len(payload)-1] = b.data[0] payload = payload[:innerPlaintextLen]
payload[innerPlaintextLen-1] = b.data[0]
// opaque_type
b.data[0] = byte(recordTypeApplicationData) b.data[0] = byte(recordTypeApplicationData)
// Add AD header, see 5.2 of RFC8446 // Add AD header, see 5.2 of RFC8446
additionalData = make([]byte, 5) additionalData = make([]byte, 5)
additionalData[0] = byte(recordTypeApplicationData) additionalData[0] = b.data[0]
binary.BigEndian.PutUint16(additionalData[1:], VersionTLS12) binary.BigEndian.PutUint16(additionalData[1:], VersionTLS12)
binary.BigEndian.PutUint16(additionalData[3:], uint16(payloadLen+overhead)) binary.BigEndian.PutUint16(additionalData[3:], uint16(innerPlaintextLen+c.Overhead()))
// make room for TLSCiphertext.encrypted_record
b.resize(innerPlaintextLen + recordHeaderLen + c.Overhead())
} }
c.Seal(payload[:0], nonce, payload, additionalData) c.Seal(payload[:0], nonce, payload, additionalData)