Change createtree's default signature algorithm from RSA to ECDSA

As requested by
#788 (comment).

Author: Rob Percival

cmd/createtree/main.go

@@ -55,7 +55,7 @@ var (
 	treeType           = flag.String("tree_type", trillian.TreeType_LOG.String(), "Type of the new tree")
 	hashStrategy       = flag.String("hash_strategy", trillian.HashStrategy_RFC6962_SHA256.String(), "Hash strategy (aka preimage protection) of the new tree")
 	hashAlgorithm      = flag.String("hash_algorithm", sigpb.DigitallySigned_SHA256.String(), "Hash algorithm of the new tree")
-	signatureAlgorithm = flag.String("signature_algorithm", sigpb.DigitallySigned_RSA.String(), "Signature algorithm of the new tree")
+	signatureAlgorithm = flag.String("signature_algorithm", sigpb.DigitallySigned_ECDSA.String(), "Signature algorithm of the new tree")
 	displayName        = flag.String("display_name", "", "Display name of the new tree")
 	description        = flag.String("description", "", "Description of the new tree")
 	maxRootDuration    = flag.Duration("max_root_duration", 0, "Interval after which a new signed root is produced despite no submissions; zero means never")

cmd/createtree/main_test.go

@@ -38,7 +38,7 @@ var defaultTree = &trillian.Tree{
 	TreeType:           trillian.TreeType_LOG,
 	HashStrategy:       trillian.HashStrategy_RFC6962_SHA256,
 	HashAlgorithm:      sigpb.DigitallySigned_SHA256,
-	SignatureAlgorithm: sigpb.DigitallySigned_RSA,
+	SignatureAlgorithm: sigpb.DigitallySigned_ECDSA,
 	PrivateKey:         mustMarshalAny(&empty.Empty{}),
 	MaxRootDuration:    ptypes.DurationProto(0 * time.Millisecond),
 }
@@ -62,7 +62,7 @@ func mustMarshalAny(p proto.Message) *any.Any {
 func TestCreateTree(t *testing.T) {
 	nonDefaultTree := *defaultTree
 	nonDefaultTree.TreeType = trillian.TreeType_MAP
-	nonDefaultTree.SignatureAlgorithm = sigpb.DigitallySigned_ECDSA
+	nonDefaultTree.SignatureAlgorithm = sigpb.DigitallySigned_RSA
 	nonDefaultTree.DisplayName = "Llamas Map"
 	nonDefaultTree.Description = "For all your digital llama needs!"