PEM encoding for GMP RSA public and private keys

src/libstrongswan/plugins/pem/Makefile.am

@@ -11,6 +11,7 @@ endif
 
 libstrongswan_pem_la_SOURCES = \
 	pem_plugin.h pem_plugin.c \
-	pem_builder.c pem_builder.h
+	pem_builder.c pem_builder.h \
+	pem_encoder.c pem_encoder.h
 
 libstrongswan_pem_la_LDFLAGS = -module -avoid-version

src/libstrongswan/plugins/pem/pem_encoder.c

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2010 Andreas Steffen
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "pem_encoder.h"
+
+#define BYTES_PER_LINE	48
+
+/**
+ * See header.
+ */
+bool pem_encoder_encode(key_encoding_type_t type, chunk_t *encoding,
+						va_list args)
+{
+	chunk_t asn1;
+	char *label;
+	u_char *pos;
+	size_t len, written, pem_chars, pem_lines;
+
+	switch (type)
+	{
+		case KEY_PUB_PEM:
+			if (!key_encoding_args(args, KEY_PART_RSA_PUB_ASN1_DER,
+								   &asn1, KEY_PART_END))
+			{
+				return FALSE;
+			}
+			label ="PUBLIC KEY";
+			break;
+		case KEY_PRIV_PEM:
+			if (!key_encoding_args(args, KEY_PART_RSA_PRIV_ASN1_DER,
+								   &asn1, KEY_PART_END))
+			{
+				return FALSE;
+			}
+			label ="RSA PRIVATE KEY";
+			break;
+		default:
+			return FALSE;
+	}
+
+	/* compute and allocate maximum size of PEM object */
+	pem_chars = 4*(asn1.len + 2)/3;
+	pem_lines = (asn1.len + BYTES_PER_LINE - 1) / BYTES_PER_LINE; 
+	*encoding = chunk_alloc(5 + 2*(6 + strlen(label) + 6) + 3 + pem_chars + pem_lines);
+	pos = encoding->ptr;
+	len = encoding->len;
+
+	/* write PEM header */
+	written = snprintf(pos, len, "-----BEGIN %s-----\n", label);
+	pos += written;
+	len -= written;	
+
+	/* write PEM body */
+	while (pem_lines--)
+	{
+		chunk_t asn1_line, pem_line;
+
+		asn1_line = chunk_create(asn1.ptr, min(asn1.len, BYTES_PER_LINE));
+		asn1.ptr += asn1_line.len;
+		asn1.len -= asn1_line.len;
+		pem_line =  chunk_to_base64(asn1_line, pos);
+		pos += pem_line.len;
+		len -= pem_line.len;
+		*pos = '\n';
+		pos++;
+		len--;
+	}
+
+	/* write PEM trailer */
+	written = snprintf(pos, len, "-----END %s-----", label);
+	pos += written;
+	len -= written;	
+
+	/* replace termination null character with newline */
+    *pos = '\n';
+	pos++;
+	len--;
+
+	/* compute effective length of PEM object */
+	encoding->len = pos - encoding->ptr;
+	return TRUE;
+}
+

src/libstrongswan/plugins/pem/pem_encoder.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2010 Andreas Steffen
+ * Hochschule fuer Technik Rapperswil
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup pem_encoder pem_encoder
+ * @{ @ingroup pem_p
+ */
+
+#ifndef PEM_ENCODER_H_
+#define PEM_ENCODER_H_
+
+#include <credentials/keys/key_encoding.h>
+
+/**
+ * Encoding from ASN.1 to PEM format.
+ */
+bool pem_encoder_encode(key_encoding_type_t type, chunk_t *encoding,
+						va_list args);
+
+#endif /** PEM_ENCODER_H_ @}*/
+

src/libstrongswan/plugins/pem/pem_plugin.c

@@ -16,7 +16,9 @@
 #include "pem_plugin.h"
 
 #include <library.h>
+
 #include "pem_builder.h"
+#include "pem_encoder.h"
 
 typedef struct private_pem_plugin_t private_pem_plugin_t;
 
@@ -100,6 +102,9 @@ plugin_t *pem_plugin_create()
 	lib->creds->add_builder(lib->creds, CRED_CERTIFICATE, CERT_PLUTO_CRL,
 							(builder_function_t)pem_certificate_load);
 
+	/* register PEM encoder */
+	lib->encoding->add_encoder(lib->encoding, pem_encoder_encode);
+
 	return &this->public.plugin;
 }