Add implementation of the RC2 block cipher (RFC 2268)

src/libstrongswan/crypto/crypters/crypter.c

@@ -46,12 +46,13 @@ ENUM_NEXT(encryption_algorithm_names, ENCR_CAMELLIA_CBC, ENCR_CAMELLIA_CCM_ICV16
 	"CAMELLIA_CCM_8",
 	"CAMELLIA_CCM_12",
 	"CAMELLIA_CCM_16");
-ENUM_NEXT(encryption_algorithm_names, ENCR_UNDEFINED, ENCR_TWOFISH_CBC, ENCR_CAMELLIA_CCM_ICV16,
+ENUM_NEXT(encryption_algorithm_names, ENCR_UNDEFINED, ENCR_RC2_CBC, ENCR_CAMELLIA_CCM_ICV16,
 	"UNDEFINED",
 	"DES_ECB",
 	"SERPENT_CBC",
-	"TWOFISH_CBC");
-ENUM_END(encryption_algorithm_names, ENCR_TWOFISH_CBC);
+	"TWOFISH_CBC",
+	"RC2_CBC");
+ENUM_END(encryption_algorithm_names, ENCR_RC2_CBC);
 
 /*
  * Described in header.

src/libstrongswan/crypto/crypters/crypter.h

@@ -60,7 +60,9 @@ enum encryption_algorithm_t {
 	ENCR_UNDEFINED =        1024,
 	ENCR_DES_ECB =          1025,
 	ENCR_SERPENT_CBC =      1026,
-	ENCR_TWOFISH_CBC =      1027
+	ENCR_TWOFISH_CBC =      1027,
+	/* see macros below to handle RC2 (effective) key length */
+	ENCR_RC2_CBC =          1028,
 };
 
 #define DES_BLOCK_SIZE			 8
@@ -70,6 +72,15 @@ enum encryption_algorithm_t {
 #define SERPENT_BLOCK_SIZE		16
 #define TWOFISH_BLOCK_SIZE		16
 
+/**
+ * For RC2, if the effective key size in bits is not key_size * 8, it should
+ * be encoded with the macro below. It can be decoded with the other two macros.
+ * After decoding the value should be validated.
+ */
+#define RC2_KEY_SIZE(kl, eff) ((kl) | ((eff) << 8))
+#define RC2_EFFECTIVE_KEY_LEN(ks) ((ks) >> 8)
+#define RC2_KEY_LEN(ks) ((ks) & 0xff)
+
 /**
  * enum name for encryption_algorithm_t.
  */