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package client
import (
"fmt"
"crypto"
"crypto/ed25519"
"crypto/tls"
"github.com/google/trillian/merkle"
"github.com/google/trillian/merkle/rfc6962"
"github.com/system-transparency/stfe"
)
func VerifySignedDebugInfoV1(sdi *stfe.StItem, scheme tls.SignatureScheme, key crypto.PublicKey, message []byte) error {
if err := supportedScheme(scheme, key); err != nil {
return err
}
if !ed25519.Verify(key.(ed25519.PublicKey), message, sdi.SignedDebugInfoV1.Signature) {
return fmt.Errorf("bad signature")
}
return nil
}
// VerifySignedTreeHeadV1 verifies an STH signature
func VerifySignedTreeHeadV1(sth *stfe.StItem, scheme tls.SignatureScheme, key crypto.PublicKey) error {
serialized, err := sth.SignedTreeHeadV1.TreeHead.Marshal()
if err != nil {
return fmt.Errorf("failed marshaling tree head: %v", err)
}
if err := supportedScheme(scheme, key); err != nil {
return err
}
if !ed25519.Verify(key.(ed25519.PublicKey), serialized, sth.SignedTreeHeadV1.Signature) {
return fmt.Errorf("bad signature")
}
return nil
}
// VerifyConsistencyProofV1 verifies that a consistency proof is valid without
// checking any sth signature
func VerifyConsistencyProofV1(proof, first, second *stfe.StItem) error {
path := make([][]byte, 0, len(proof.ConsistencyProofV1.ConsistencyPath))
for _, nh := range proof.ConsistencyProofV1.ConsistencyPath {
path = append(path, nh.Data)
}
return merkle.NewLogVerifier(rfc6962.DefaultHasher).VerifyConsistencyProof(
int64(proof.ConsistencyProofV1.TreeSize1),
int64(proof.ConsistencyProofV1.TreeSize2),
first.SignedTreeHeadV1.TreeHead.RootHash.Data,
second.SignedTreeHeadV1.TreeHead.RootHash.Data,
path,
)
}
// VerifyInclusionProofV1 verifies that an inclusion proof is valid without checking
// any sth signature
func VerifyInclusionProofV1(proof *stfe.StItem, rootHash, leafHash []byte) error {
path := make([][]byte, 0, len(proof.InclusionProofV1.InclusionPath))
for _, nh := range proof.InclusionProofV1.InclusionPath {
path = append(path, nh.Data)
}
return merkle.NewLogVerifier(rfc6962.DefaultHasher).VerifyInclusionProof(
int64(proof.InclusionProofV1.LeafIndex),
int64(proof.InclusionProofV1.TreeSize),
path,
rootHash,
leafHash,
)
}
// supportedScheme checks whether the client library supports the log's
// signature scheme and public key type
func supportedScheme(scheme tls.SignatureScheme, key crypto.PublicKey) error {
if _, ok := key.(ed25519.PublicKey); ok && scheme == tls.Ed25519 {
return nil
}
switch t := key.(type) {
default:
return fmt.Errorf("unsupported scheme(%v) and key(%v)", scheme, t)
}
}
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