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-rwxr-xr-xsrc/charon/lib/asn1/pem.c343
1 files changed, 343 insertions, 0 deletions
diff --git a/src/charon/lib/asn1/pem.c b/src/charon/lib/asn1/pem.c
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+++ b/src/charon/lib/asn1/pem.c
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+/*
+ * 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_hash_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;
+}
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