curve25519: Support loading Ed25519 public keys from simple blobs

src/libstrongswan/credentials/builder.c

@@ -73,6 +73,7 @@ ENUM(builder_part_names, BUILD_FROM_FILE, BUILD_END,
 	"BUILD_SAFE_PRIMES",
 	"BUILD_SHARES",
 	"BUILD_THRESHOLD",
+	"BUILD_EDDSA_PUB",
 	"BUILD_EDDSA_PRIV_ASN1_DER",
 	"BUILD_END",
 );

src/libstrongswan/credentials/builder.h

@@ -156,6 +156,8 @@ enum builder_part_t {
 	BUILD_SHARES,
 	/** minimum number of participating private key shares */
 	BUILD_THRESHOLD,
+	/** EdDSA public key blob */
+	BUILD_EDDSA_PUB,
 	/** DER encoded ASN.1 EdDSA private key */
 	BUILD_EDDSA_PRIV_ASN1_DER,
 	/** end of variable argument builder list */

src/libstrongswan/plugins/curve25519/curve25519_public_key.c

@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2018 Tobias Brunner
  * Copyright (C) 2016 Andreas Steffen
  * HSR Hochschule fuer Technik Rapperswil
  *
@@ -200,50 +201,16 @@ static const asn1Object_t pubkeyObjects[] = {
 #define ED25519_SUBJECT_PUBLIC_KEY				2
 
 /**
- * See header.
+ * Parse the ASN.1-encoded subjectPublicKeyInfo
  */
-curve25519_public_key_t *curve25519_public_key_load(key_type_t type,
+static bool parse_public_key_info(private_curve25519_public_key_t *this,
-													va_list args)
+								  chunk_t blob)
 {
-	private_curve25519_public_key_t *this;
-	chunk_t blob = chunk_empty, object;
 	asn1_parser_t *parser;
+	chunk_t object;
 	bool success = FALSE;
 	int objectID, oid;
 
-	while (TRUE)
-	{
-		switch (va_arg(args, builder_part_t))
-		{
-			case BUILD_BLOB_ASN1_DER:
-				blob = va_arg(args, chunk_t);
-				continue;
-			case BUILD_END:
-				break;
-			default:
-				return NULL;
-		}
-		break;
-	}
-
-	INIT(this,
-		.public = {
-			.key = {
-				.get_type = _get_type,
-				.verify = _verify,
-				.encrypt = _encrypt_,
-				.equals = public_key_equals,
-				.get_keysize = _get_keysize,
-				.get_fingerprint = _get_fingerprint,
-				.has_fingerprint = public_key_has_fingerprint,
-				.get_encoding = _get_encoding,
-				.get_ref = _get_ref,
-				.destroy = _destroy,
-			},
-		},
-		.ref = 1,
-	);
-
 	parser = asn1_parser_create(pubkeyObjects, blob);
 
 	while (parser->iterate(parser, &objectID, &object))
@@ -276,7 +243,59 @@ curve25519_public_key_t *curve25519_public_key_load(key_type_t type,
 
 end:
 	parser->destroy(parser);
-	if (!success)
+	return success;
+}
+
+/**
+ * See header.
+ */
+curve25519_public_key_t *curve25519_public_key_load(key_type_t type,
+													va_list args)
+{
+	private_curve25519_public_key_t *this;
+	chunk_t asn1 = chunk_empty, blob = chunk_empty;
+
+	while (TRUE)
+	{
+		switch (va_arg(args, builder_part_t))
+		{
+			case BUILD_BLOB_ASN1_DER:
+				asn1 = va_arg(args, chunk_t);
+				continue;
+			case BUILD_EDDSA_PUB:
+				blob = va_arg(args, chunk_t);
+				continue;
+			case BUILD_END:
+				break;
+			default:
+				return NULL;
+		}
+		break;
+	}
+
+	INIT(this,
+		.public = {
+			.key = {
+				.get_type = _get_type,
+				.verify = _verify,
+				.encrypt = _encrypt_,
+				.equals = public_key_equals,
+				.get_keysize = _get_keysize,
+				.get_fingerprint = _get_fingerprint,
+				.has_fingerprint = public_key_has_fingerprint,
+				.get_encoding = _get_encoding,
+				.get_ref = _get_ref,
+				.destroy = _destroy,
+			},
+		},
+		.ref = 1,
+	);
+
+	if (blob.len == ED25519_KEY_LEN)
+	{
+		this->pubkey = chunk_clone(blob);
+	}
+	else if (!asn1.len || !parse_public_key_info(this, asn1))
 	{
 		destroy(this);
 		return NULL;