- using asn1 pluto stuff now

Source/lib/asn1/pem.c

@@ -0,0 +1,343 @@
+/*
+ * Copyright (C) 2005 Jan Hutter, Martin Willi
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <stddef.h>
+#include <sys/types.h>
+
+#include "pem.h"
+#include "ttodata.h"
+
+#include <crypto/hashers/hasher.h>
+#include <crypto/crypters/crypter.h>
+
+
+/*
+ * check the presence of a pattern in a character string
+ */
+static bool present(const char* pattern, chunk_t* ch)
+{
+	u_int pattern_len = strlen(pattern);
+
+	if (ch->len >= pattern_len && strncmp(ch->ptr, pattern, pattern_len) == 0)
+	{
+		ch->ptr += pattern_len;
+		ch->len -= pattern_len;
+		return TRUE;
+	}
+	return FALSE;
+}
+
+/*
+ * compare string with chunk
+ */
+static bool match(const char *pattern, const chunk_t *ch)
+{
+	return ch->len == strlen(pattern) && strncmp(pattern, ch->ptr, ch->len) == 0;
+}
+
+/*
+ * find a boundary of the form -----tag name-----
+ */
+static bool find_boundary(const char* tag, chunk_t *line)
+{
+	chunk_t name = CHUNK_INITIALIZER;
+
+	if (!present("-----", line))
+		return FALSE;
+	if (!present(tag, line))
+		return FALSE;
+	if (*line->ptr != ' ')
+		return FALSE;
+	line->ptr++;  line->len--;
+	
+	/* extract name */
+	name.ptr = line->ptr;
+	while (line->len > 0)
+	{
+		if (present("-----", line))
+		{
+			return TRUE;
+		}
+		line->ptr++;  line->len--;  name.len++;
+	}
+	return FALSE;
+}
+
+/*
+ * eat whitespace
+ */
+static void eat_whitespace(chunk_t *src)
+{
+	while (src->len > 0 && (*src->ptr == ' ' || *src->ptr == '\t'))
+	{
+		src->ptr++;  src->len--;
+	}
+}
+
+/*
+ * extracts a token ending with a given termination symbol
+ */
+static bool extract_token(chunk_t *token, char termination, chunk_t *src)
+{
+	u_char *eot = memchr(src->ptr, termination, src->len);
+	
+	/* initialize empty token */
+	*token = CHUNK_INITIALIZER;
+	
+	if (eot == NULL) /* termination symbol not found */
+	{
+		return FALSE;
+	}
+	
+	/* extract token */
+	token->ptr = src->ptr;
+	token->len = (u_int)(eot - src->ptr);
+	
+	/* advance src pointer after termination symbol */
+	src->ptr = eot + 1;
+	src->len -= (token->len + 1);
+	
+	return TRUE;
+}
+
+/*
+ * extracts a name: value pair from the PEM header
+ */
+static bool extract_parameter(chunk_t *name, chunk_t *value, chunk_t *line)
+{
+	/* extract name */
+	if (!extract_token(name,':', line))
+	{
+		return FALSE;
+	}
+	
+	eat_whitespace(line);
+	
+	/* extract value */
+	*value = *line;
+	return TRUE;
+}
+
+/*
+ *  fetches a new line terminated by \n or \r\n
+ */
+static bool fetchline(chunk_t *src, chunk_t *line)
+{
+	if (src->len == 0) /* end of src reached */
+		return FALSE;
+
+	if (extract_token(line, '\n', src))
+	{
+		if (line->len > 0 && *(line->ptr + line->len -1) == '\r')
+			line->len--;  /* remove optional \r */
+	}
+	else /*last line ends without newline */
+	{
+		*line = *src;
+		src->ptr += src->len;
+		src->len = 0;
+	}
+	return TRUE;
+}
+
+/*
+ * decrypts a DES-EDE-CBC encrypted data block
+ */
+static status_t pem_decrypt(chunk_t *blob, chunk_t *iv, char *passphrase)
+{
+	hasher_t *hasher;
+	crypter_t *crypter;
+	chunk_t hash;
+	chunk_t decrypted;
+	chunk_t pass = {passphrase, strlen(passphrase)};
+	chunk_t key = {alloca(24), 24};
+	u_int8_t padding, *last_padding_pos, *first_padding_pos;
+	
+	/* build key from passphrase and IV */
+	hasher = hasher_create(HASH_MD5);
+	hash.len = hasher->get_block_size(hasher);
+	hash.ptr = alloca(hash.len);
+	hasher->get_hash(hasher, pass, NULL);
+	hasher->get_hash(hasher, *iv, hash.ptr);
+	
+	memcpy(key.ptr, hash.ptr, hash.len);
+	
+	hasher->get_hash(hasher, hash, NULL);
+	hasher->get_hash(hasher, pass, NULL);
+	hasher->get_hash(hasher, *iv, hash.ptr);
+	
+	memcpy(key.ptr + hash.len, hash.ptr, key.len - hash.len);
+	
+	hasher->destroy(hasher);
+	
+	/* decrypt blob */
+	crypter = crypter_create(ENCR_3DES, 0);
+	crypter->set_key(crypter, key);
+	crypter->decrypt(crypter, *blob, *iv, &decrypted);
+	memcpy(blob->ptr, decrypted.ptr, blob->len);
+	chunk_free(&decrypted);
+	
+	/* determine amount of padding */
+	last_padding_pos = blob->ptr + blob->len - 1;
+	padding = *last_padding_pos;
+	first_padding_pos = (padding > blob->len) ? blob->ptr : last_padding_pos - padding;
+
+	/* check the padding pattern */
+	while (--last_padding_pos > first_padding_pos)
+	{
+		if (*last_padding_pos != padding)
+			return FALSE;
+	}
+	/* remove padding */
+	blob->len -= padding;
+	return TRUE;
+}
+
+/*  Converts a PEM encoded file into its binary form
+ *
+ *  RFC 1421 Privacy Enhancement for Electronic Mail, February 1993
+ *  RFC 934 Message Encapsulation, January 1985
+ */
+status_t pemtobin(chunk_t *blob, char *pass)
+{
+	typedef enum {
+		PEM_PRE    = 0,
+		PEM_MSG    = 1,
+		PEM_HEADER = 2,
+		PEM_BODY   = 3,
+		PEM_POST   = 4,
+		PEM_ABORT  = 5
+	} state_t;
+
+	bool encrypted = FALSE;
+
+	state_t state  = PEM_PRE;
+
+	chunk_t src    = *blob;
+	chunk_t dst    = *blob;
+	chunk_t line   = CHUNK_INITIALIZER;
+	chunk_t iv     = CHUNK_INITIALIZER;
+
+	u_char iv_buf[16]; /* MD5 digest size */
+
+	/* zero size of converted blob */
+	dst.len = 0;
+
+	/* zero size of IV */
+	iv.ptr = iv_buf;
+	iv.len = 0;
+
+	while (fetchline(&src, &line))
+	{
+		if (state == PEM_PRE)
+		{
+			if (find_boundary("BEGIN", &line))
+			{
+				state = PEM_MSG;
+			}
+			continue;
+		}
+		else
+		{
+			if (find_boundary("END", &line))
+			{
+				state = PEM_POST;
+				break;
+			}
+			if (state == PEM_MSG)
+			{
+				state = (memchr(line.ptr, ':', line.len) == NULL) ? PEM_BODY : PEM_HEADER;
+			}
+			if (state == PEM_HEADER)
+			{
+				chunk_t name  = CHUNK_INITIALIZER;
+				chunk_t value = CHUNK_INITIALIZER;
+
+				/* an empty line separates HEADER and BODY */
+				if (line.len == 0)
+				{
+					state = PEM_BODY;
+					continue;
+				}
+
+				/* we are looking for a name: value pair */
+				if (!extract_parameter(&name, &value, &line))
+					continue;
+
+				if (match("Proc-Type", &name) && *value.ptr == '4')
+					encrypted = TRUE;
+				else if (match("DEK-Info", &name))
+				{
+					const char *ugh = NULL;
+					size_t len = 0;
+					chunk_t dek;
+
+					if (!extract_token(&dek, ',', &value))
+						dek = value;
+
+					/* we support DES-EDE3-CBC encrypted files, only */
+					if (!match("DES-EDE3-CBC", &dek))
+						return NOT_SUPPORTED;
+
+					eat_whitespace(&value);
+					ugh = ttodata(value.ptr, value.len, 16, iv.ptr, 16, &len);
+					if (ugh)
+						return PARSE_ERROR;
+
+					iv.len = len;
+				}
+			}
+			else /* state is PEM_BODY */
+			{
+				const char *ugh = NULL;
+				size_t len = 0;
+				chunk_t data;
+				
+				/* remove any trailing whitespace */
+				if (!extract_token(&data ,' ', &line))
+				{
+					data = line;
+				}
+				
+				ugh = ttodata(data.ptr, data.len, 64, dst.ptr, blob->len - dst.len, &len);
+				if (ugh)
+				{
+					state = PEM_ABORT;
+					break;
+				}
+				else
+				{
+					dst.ptr += len;
+					dst.len += len;
+				}
+			}
+		}
+	}
+	/* set length to size of binary blob */
+	blob->len = dst.len;
+
+	if (state != PEM_POST)
+		return PARSE_ERROR;
+
+	if (encrypted)
+		return pem_decrypt(blob, &iv, pass);
+	else
+		return SUCCESS;
+}