add cosign command

1 files changed, 41 insertions, 0 deletions

diff --git a/cmd/sigsum-debug/cosign/cosign.go b/cmd/sigsum-debug/cosign/cosign.go
new file mode 100644
index 0000000..8597cc6
--- /dev/null
+++ b/cmd/sigsum-debug/cosign/cosign.go
@@ -0,0 +1,41 @@
+package cosign
+
+import (
+	"bytes"
+	"fmt"
+
+	"git.sigsum.org/sigsum-go/pkg/hex"
+	"git.sigsum.org/sigsum-go/pkg/types"
+	"git.sigsum.org/sigsum-tools-go/internal/util"
+)
+
+func Main(_ []string, optPriv, optPub string) error {
+	priv, err := util.SignerFromHex(optPriv)
+	if err != nil {
+		return fmt.Errorf("cosign: %v", err)
+	}
+	b, err := hex.Deserialize(optPub)
+	if err != nil {
+		return fmt.Errorf("cosign: %v", err)
+	}
+	if len(b) != types.PublicKeySize {
+		return fmt.Errorf("cosign: invalid public key length %d", len(b))
+	}
+	var pub types.PublicKey
+	copy(pub[:], b)
+	data, err := util.BytesFromStdin()
+	if err != nil {
+		return fmt.Errorf("cosign: %v", err)
+	}
+	var sth types.SignedTreeHead
+	if err := sth.FromASCII(bytes.NewBuffer(data)); err != nil {
+		return fmt.Errorf("cosign: %v", err)
+	}
+	witSTH, err := sth.TreeHead.Sign(priv, types.HashFn(pub[:]))
+	if err != nil {
+		return fmt.Errorf("cosign: %v", err)
+	}
+
+	fmt.Printf("%s\n", hex.Serialize(witSTH.Signature[:]))
+	return nil
+}