Ilia Denisov
81 lines
2.6 KiB
Go
81 lines
2.6 KiB
Go
package authn
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import (
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"crypto/ed25519"
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"encoding/binary"
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"errors"
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)
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const (
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// EventDomainMarkerV1 binds the v1 server event signature to the Galaxy
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// gateway transport contract.
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EventDomainMarkerV1 = "galaxy-event-v1"
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)
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var (
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// ErrInvalidEventSignature reports that a gateway stream event signature is
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// not a raw Ed25519 signature for the canonical event signing input.
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ErrInvalidEventSignature = errors.New("invalid event signature")
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)
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// EventSigningFields contains the canonical v1 stream-event fields that are
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// bound into the server signing input.
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type EventSigningFields struct {
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// EventType identifies the stable client-facing event category.
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EventType string
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// EventID is the stable event correlation identifier.
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EventID string
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// TimestampMS carries the server event timestamp in milliseconds.
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TimestampMS int64
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// RequestID optionally correlates the event to the opening client request.
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RequestID string
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// TraceID optionally carries the client-supplied tracing correlation value.
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TraceID string
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// PayloadHash is the raw SHA-256 digest of event payload bytes.
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PayloadHash []byte
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}
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// BuildEventSigningInput returns the canonical byte sequence the v1 gateway
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// stream-event signature covers. String and byte fields are length-prefixed
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// with uvarint(len(field)) followed by raw bytes, while TimestampMS is
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// appended as an 8-byte big-endian uint64.
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func BuildEventSigningInput(fields EventSigningFields) []byte {
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size := len(EventDomainMarkerV1) +
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len(fields.EventType) +
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len(fields.EventID) +
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len(fields.RequestID) +
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len(fields.TraceID) +
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len(fields.PayloadHash) +
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(6 * binary.MaxVarintLen64) +
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8
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buf := make([]byte, 0, size)
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buf = appendLengthPrefixedString(buf, EventDomainMarkerV1)
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buf = appendLengthPrefixedString(buf, fields.EventType)
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buf = appendLengthPrefixedString(buf, fields.EventID)
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buf = binary.BigEndian.AppendUint64(buf, uint64(fields.TimestampMS))
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buf = appendLengthPrefixedString(buf, fields.RequestID)
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buf = appendLengthPrefixedString(buf, fields.TraceID)
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buf = appendLengthPrefixedBytes(buf, fields.PayloadHash)
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return buf
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}
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// VerifyEventSignature verifies that signature authenticates fields under
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// publicKey using the canonical v1 event signing input.
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func VerifyEventSignature(publicKey ed25519.PublicKey, signature []byte, fields EventSigningFields) error {
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if len(publicKey) != ed25519.PublicKeySize || len(signature) != ed25519.SignatureSize {
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return ErrInvalidEventSignature
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}
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if !ed25519.Verify(publicKey, BuildEventSigningInput(fields), signature) {
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return ErrInvalidEventSignature
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}
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return nil
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}
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