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52 lines
2.2 KiB
Go
52 lines
2.2 KiB
Go
package noiseutil
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import (
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"errors"
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"fmt"
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"math"
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"github.com/flynn/noise"
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)
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// RejectHeadroom is the wrap gap for senders racing the counter, sized large enough for any routine count.
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const RejectHeadroom = uint64(1) << 40
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// RejectAfterMessages is the nonce ceiling: encrypting stops RejectHeadroom short of the wrap.
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const RejectAfterMessages = math.MaxUint64 - RejectHeadroom
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// ErrMessageCounterExhausted is returned by EncryptDanger once the nonce reaches RejectAfterMessages.
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var ErrMessageCounterExhausted = errors.New("message counter exhausted")
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// CipherState is the post-handshake AEAD cipher used for the data plane.
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// Each supported cipher has its own concrete implementation in this package with the nonce endianness hardcoded,
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// so the encrypt/decrypt fast path avoids interface dispatch on the byte order.
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type CipherState interface {
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// EncryptDanger encrypts and authenticates a given payload.
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//
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// out is a destination slice to hold the output of the EncryptDanger operation.
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// - ad is additional data, which will be authenticated and appended to out, but not encrypted.
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// - plaintext is encrypted, authenticated and appended to out.
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// - n is a nonce value which must never be re-used with this key.
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// - nb is a scratch buffer used to assemble the nonce.
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EncryptDanger(out, ad, plaintext []byte, n uint64, nb []byte) ([]byte, error)
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// DecryptDanger authenticates and decrypts a given payload, with the same argument shape as EncryptDanger.
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DecryptDanger(out, ad, ciphertext []byte, n uint64, nb []byte) ([]byte, error)
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// Overhead returns the AEAD tag size, or 0 if the receiver is nil.
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Overhead() int
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}
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// NewCipherState wraps the post-handshake noise.CipherState in the per-cipher type that matches cipherFunc.
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// cipherFunc must be the same cipher used to build the noise CipherSuite that produced s.
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func NewCipherState(s *noise.CipherState, cipherFunc noise.CipherFunc) CipherState {
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switch cipherFunc.CipherName() {
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case CipherAESGCM.CipherName():
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return NewCipherStateAESGCM(s)
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case noise.CipherChaChaPoly.CipherName():
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return NewCipherStateChaChaPoly(s)
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default:
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panic(fmt.Sprintf("noiseutil: unsupported cipher %q", cipherFunc.CipherName()))
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}
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}
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