2 files changed, 98 insertions, 0 deletions
diff --git a/pkg/policy/default.go b/pkg/policy/default.go
new file mode 100644
index 0000000..6f35fa4
--- /dev/null
+++ b/pkg/policy/default.go
@@ -0,0 +1,66 @@
+package policy
+
+import (
+	"fmt"
+
+	"git.sigsum.org/sigsum-lib-go/pkg/types"
+)
+
+type DefaultPolicy struct{}
+
+// Verify checks if the cosigned tree head satisifies the policy "one log and
+// a majority of witnesses".  Any unverifiable cosignatures are removed.
+func (dp *DefaultPolicy) Verify(*types.CosignedTreeHead) error {
+	return fmt.Errorf("TODO")
+}
+
+func (dp *DefaultPolicy) Logs() []Log {
+	return []Log{
+		Log{
+			Name:   "Test log operated by ln5",
+			LogURL: "https://poc.sigsum.org/glasswing-butterfly/sigsum/v0",
+			PublicKey: types.PublicKey{
+				74, 179, 210, 181,
+				30, 71, 220, 157,
+				228, 204, 228, 189,
+				235, 169, 224, 134,
+				34, 233, 58, 47,
+				127, 137, 180, 203,
+				119, 25, 127, 198,
+				176, 4, 77, 231,
+			},
+			ShardStart: 1639579652,
+			TrustUntil: 1648771200, // Apr 1 2022
+		},
+	}
+}
+
+func (dp *DefaultPolicy) Witnesses() []Witness {
+	return []Witness{
+		Witness{
+			Name: "Test witness operated by rgdd",
+			PublicKey: types.PublicKey{
+				129, 45, 190, 240,
+				21, 107, 7, 158,
+				45, 4, 135, 71,
+				178, 24, 156, 191,
+				166, 79, 150, 226,
+				32, 74, 23, 203,
+				35, 203, 82, 128,
+				128, 135, 21, 3,
+			},
+			TrustUntil: 1648771200, // Apr 1 2022
+		},
+	}
+}
+
+// ShardHint returns the smallest shard hint that all logs accept
+func (dp *DefaultPolicy) ShardHint() uint64 {
+	var shardHint uint64
+	for _, l := range dp.Logs() {
+		if l.ShardStart > shardHint {
+			shardHint = l.ShardStart
+		}
+	}
+	return shardHint
+}
diff --git a/pkg/policy/policy.go b/pkg/policy/policy.go
new file mode 100644
index 0000000..b4fe920
--- /dev/null
+++ b/pkg/policy/policy.go
@@ -0,0 +1,32 @@
+package policy
+
+import (
+	"git.sigsum.org/sigsum-lib-go/pkg/types"
+)
+
+type Policy interface {
+	// Logs returns the list of known logs.  It is needed so that an
+	// appropriate log can be picked when submitting a signed checksum.
+	Logs() []Log
+
+	// ShardHint returns a recommended shard hint.
+	ShardHint() uint64
+
+	// Verify checks if a cosigned tree head is trustworthy.  On success,
+	// any invalid or unknown cosignatures may be removed.
+	Verify(*types.CosignedTreeHead) error
+}
+
+type Log struct {
+	Name       string
+	LogURL     string
+	PublicKey  types.PublicKey
+	ShardStart uint64
+	TrustUntil uint64
+}
+
+type Witness struct {
+	Name       string
+	PublicKey  types.PublicKey
+	TrustUntil uint64
+}