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Diffstat (limited to 'Build/source/texk/dvipdfm-x/xsrc/pdfencrypt.c')
-rw-r--r-- | Build/source/texk/dvipdfm-x/xsrc/pdfencrypt.c | 539 |
1 files changed, 539 insertions, 0 deletions
diff --git a/Build/source/texk/dvipdfm-x/xsrc/pdfencrypt.c b/Build/source/texk/dvipdfm-x/xsrc/pdfencrypt.c new file mode 100644 index 00000000000..464f97e2b3d --- /dev/null +++ b/Build/source/texk/dvipdfm-x/xsrc/pdfencrypt.c @@ -0,0 +1,539 @@ +/* + + This is dvipdfmx, an eXtended version of dvipdfm by Mark A. Wicks. + + Copyright (C) 2002-2012 by Jin-Hwan Cho and Shunsaku Hirata, + the dvipdfmx project team. + + 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. + + 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. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. +*/ + +#if HAVE_CONFIG_H +#include "config.h" +#endif + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> + +#ifdef WIN32 +#include <conio.h> +#define getch _getch +#else /* !WIN32 */ +#include <unistd.h> +#endif /* WIN32 */ + +#include "system.h" +#include "mem.h" +#include "error.h" +#include "pdfobj.h" +#include "dpxcrypt.h" + +#include "pdfencrypt.h" + +#define MAX_KEY_LEN 16 +#define MAX_STR_LEN 32 + +static unsigned char algorithm, revision, key_size; +static unsigned long permission; + +static unsigned char key_data[MAX_KEY_LEN], id_string[MAX_KEY_LEN]; +static unsigned char opwd_string[MAX_STR_LEN], upwd_string[MAX_STR_LEN]; + +static unsigned long current_label = 0; +static unsigned current_generation = 0; + +static ARC4_KEY key; +static MD5_CONTEXT md5_ctx; + +static unsigned char md5_buf[MAX_KEY_LEN], key_buf[MAX_KEY_LEN]; +static unsigned char in_buf[MAX_STR_LEN], out_buf[MAX_STR_LEN]; + +static const unsigned char padding_string[MAX_STR_LEN] = { + 0x28, 0xbf, 0x4e, 0x5e, 0x4e, 0x75, 0x8a, 0x41, + 0x64, 0x00, 0x4e, 0x56, 0xff, 0xfa, 0x01, 0x08, + 0x2e, 0x2e, 0x00, 0xb6, 0xd0, 0x68, 0x3e, 0x80, + 0x2f, 0x0c, 0xa9, 0xfe, 0x64, 0x53, 0x69, 0x7a +}; + +static char owner_passwd[MAX_PWD_LEN], user_passwd[MAX_PWD_LEN]; + +static unsigned char verbose = 0; + +void pdf_enc_set_verbose (void) +{ + if (verbose < 255) verbose++; +} + +#define PRODUCER "%s-%s, Copyright \251 2002-2010 by Jin-Hwan Cho, Matthias Franz, and Shunsaku Hirata" +void pdf_enc_compute_id_string (char *dviname, char *pdfname) +{ + char *date_string, *producer; + time_t current_time; + struct tm *bd_time; + + MD5_init(&md5_ctx); + + date_string = NEW (15, char); + time(¤t_time); + bd_time = localtime(¤t_time); + sprintf (date_string, "%04d%02d%02d%02d%02d%02d", + bd_time -> tm_year+1900, bd_time -> tm_mon+1, bd_time -> tm_mday, + bd_time -> tm_hour, bd_time -> tm_min, bd_time -> tm_sec); + MD5_write(&md5_ctx, (unsigned char *)date_string, strlen(date_string)); + RELEASE (date_string); + + producer = NEW (strlen(PRODUCER)+strlen(PACKAGE)+strlen(VERSION), char); + sprintf(producer, PRODUCER, PACKAGE, VERSION); + MD5_write(&md5_ctx, (unsigned char *)producer, strlen(producer)); + RELEASE (producer); + + if (dviname) + MD5_write(&md5_ctx, (unsigned char *)dviname, strlen(dviname)); + if (pdfname) + MD5_write(&md5_ctx, (unsigned char *)pdfname, strlen(pdfname)); + MD5_final(id_string, &md5_ctx); +} + +static void passwd_padding (unsigned char *src, unsigned char *dst) +{ + register int len = strlen((char *)src); + + if (len > MAX_STR_LEN) + len = MAX_STR_LEN; + + memcpy(dst, src, len); + memcpy(dst+len, padding_string, MAX_STR_LEN-len); +} + +static void compute_owner_password (void) +{ + register unsigned char i, j; + /* + * Algorithm 3.3 Computing the encryption dictionary's O (owner password) + * value + * + * 1. Pad or truncate the owner password string as described in step 1 + * of Algorithm 3.2. If there is no owner password, use the user + * password instead. (See implementation note 17 in Appendix H.) + */ + passwd_padding((unsigned char *)(strlen(owner_passwd) > 0 ? owner_passwd : user_passwd), in_buf); + /* + * 2. Initialize the MD5 hash function and pass the result of step 1 + * as input to this function. + */ + MD5_init(&md5_ctx); + MD5_write(&md5_ctx, in_buf, MAX_STR_LEN); + MD5_final(md5_buf, &md5_ctx); + /* + * 3. (Revision 3 only) Do the following 50 times: Take the output + * from the previous MD5 hash and pass it as input into a new + * MD5 hash. + */ + if (revision == 3) + for (i = 0; i < 50; i++) { + /* + * NOTE: We truncate each MD5 hash as in the following step. + * Otherwise Adobe Reader won't decrypt the PDF file. + */ + MD5_init(&md5_ctx); + MD5_write(&md5_ctx, md5_buf, key_size); + MD5_final(md5_buf, &md5_ctx); + } + /* + * 4. Create an RC4 encryption key using the first n bytes of the output + * from the final MD5 hash, where n is always 5 for revision 2 but + * for revision 3 depends on the value of the encryption dictionary's + * Length entry. + */ + ARC4_set_key(&key, key_size, md5_buf); + /* + * 5. Pad or truncate the user password string as described in step 1 + * of Algorithm 3.2. + */ + passwd_padding((unsigned char *)user_passwd, in_buf); + /* + * 6. Encrypt the result of step 5, using an RC4 encryption function + * with the encryption key obtained in step 4. + */ + ARC4(&key, MAX_STR_LEN, in_buf, out_buf); + /* + * 7. (Revision 3 only) Do the following 19 times: Take the output + * from the previous invocation of the RC4 function and pass it + * as input to a new invocation of the function; use an encryption + * key generated by taking each byte of the encryption key obtained + * in step 4 and performing an XOR (exclusive or) operation between + * that byte and the single-byte value of the iteration counter + * (from 1 to 19). + */ + if (revision == 3) + for (i = 1; i <= 19; i++) { + memcpy(in_buf, out_buf, MAX_STR_LEN); + for (j = 0; j < key_size; j++) + key_buf[j] = md5_buf[j] ^ i; + ARC4_set_key(&key, key_size, key_buf); + ARC4(&key, MAX_STR_LEN, in_buf, out_buf); + } + /* + * 8. Store the output from the final invocation of the RC4 function + * as the value of the O entry in the encryption dictionary. + */ + memcpy(opwd_string, out_buf, MAX_STR_LEN); +} + +static void compute_encryption_key (unsigned char *pwd) +{ + register unsigned char i; + /* + * Algorithm 3.2 Computing an encryption key + * + * 1. Pad or truncate the password string to exactly 32 bytes. If the + * password string is more than 32 bytes long, use only its first + * 32 bytes; if it is less than 32 bytes long, pad it by appending + * the required number of additional bytes from the beginning of + * the following padding string: + * + * < 28 BF 4E 5E 4E 75 8A 41 64 00 4E 56 FF FA 01 08 + * 2E 2E 00 B6 D0 68 3E 80 2F 0C A9 FE 64 53 69 7A > + * + * That is, if the password string is n bytes long, append the + * first 32 - n bytes of the padding string to the end of the + * password string. If the password string is empty (zero-length), + * meaning there is no user password, substitute the entire + * padding string in its place. + */ + passwd_padding(pwd, in_buf); + /* + * 2. Initialize the MD5 hash function and pass the result of step 1 + * as input to this fuction. + */ + MD5_init(&md5_ctx); + MD5_write(&md5_ctx, in_buf, MAX_STR_LEN); + /* + * 3. Pass the value of the encryption dictionary's O entry to the + * MD5 hash function. (Algorithm 3.3 shows how the O value is + * computed.) + */ + MD5_write(&md5_ctx, opwd_string, MAX_STR_LEN); + /* + * 4. Treat the value of the P entry as an unsigned 4-byte integer + * and pass these bytes to the MD5 hash function, low-order byte + * first. + */ + in_buf[0] = (unsigned char)(permission) & 0xFF; + in_buf[1] = (unsigned char)(permission >> 8) & 0xFF; + in_buf[2] = (unsigned char)(permission >> 16) & 0xFF; + in_buf[3] = (unsigned char)(permission >> 24) & 0xFF; + MD5_write(&md5_ctx, in_buf, 4); + /* + * 5. Pass the first element of the file's file identifier array + * (the value of the ID entry in the document's trailer dictionary; + * see Table 3.12 on page 68) to the MD5 hash function and + * finish the hash. + */ + MD5_write(&md5_ctx, id_string, MAX_KEY_LEN); + MD5_final(md5_buf, &md5_ctx); + /* + * 6. (Revision 3 only) Do the following 50 times; Take the output from + * the previous MD5 hash and pass it as input into a new MD5 hash. + */ + if (revision == 3) + for (i = 0; i < 50; i++) { + /* + * NOTE: We truncate each MD5 hash as in the following step. + * Otherwise Adobe Reader won't decrypt the PDF file. + */ + MD5_init(&md5_ctx); + MD5_write(&md5_ctx, md5_buf, key_size); + MD5_final(md5_buf, &md5_ctx); + } + /* + * 7. Set the encryption key to the first n bytes of the output from + * the final MD5 hash, where n is always 5 for revision 2 but for + * revision 3 depends on the value of the encryption dictionary's + * Length entry. + */ + memcpy(key_data, md5_buf, key_size); +} + +static void compute_user_password (void) +{ + register unsigned char i, j; + /* + * Algorithm 3.4 Computing the encryption dictionary's U (user password) + * value (Revision 2) + * + * 1. Create an encryption key based on the user password string, as + * described in Algorithm 3.2. + * + * 2. Encrypt the 32-byte padding string shown in step 1 of Algorithm + * 3.2, using an RC4 encryption fuction with the encryption key from + * the preceeding step. + * + * 3. Store the result of step 2 as the value of the U entry in the + * encryption dictionary. + */ + /* + * Algorithm 3.5 Computing the encryption dictionary's U (user password) + * value (Revision 3) + * + * 1. Create an encryption key based on the user password string, as + * described in Algorithm 3.2. + * + * 2. Initialize the MD5 hash function and pass the 32-byte padding + * string shown in step 1 of Algorithm 3.2 as input to this function. + * + * 3. Pass the first element of the file's file identifier array (the + * value of the ID entry in the document's trailer dictionary; see + * Table 3.12 on page 68) to the hash function and finish the hash. + * + * 4. Encrypt the 16-byte result of the hash, using an RC4 encryption + * function with the encryption key from step 1. + * + * 5. Do the following 19 times: Take the output from the previous + * invocation of the RC4 function and pass it as input to a new + * invocation of the function; use an encryption key generated by + * taking each byte of the original encryption key (obtained in + * step 1) and performing an XOR (exclusive or) operation between + * that byte and the single-byte value of the iteration counter + * (from 1 to 19). + * + * 6. Append 16 bytes of arbitrary padding to the output from the + * final invocation of the RC4 function and store the 32-byte + * result as the value of the U entry in the encryption dictionary. + */ + compute_encryption_key((unsigned char *)user_passwd); + + switch (revision) { + case 2: + ARC4_set_key(&key, key_size, key_data); + ARC4(&key, MAX_STR_LEN, padding_string, out_buf); + break; + case 3: + MD5_init(&md5_ctx); + MD5_write(&md5_ctx, padding_string, MAX_STR_LEN); + + MD5_write(&md5_ctx, id_string, MAX_KEY_LEN); + MD5_final(md5_buf, &md5_ctx); + + ARC4_set_key(&key, key_size, key_data); + ARC4(&key, MAX_KEY_LEN, md5_buf, out_buf); + + for (i = 1; i <= 19; i++) { + memcpy(in_buf, out_buf, MAX_KEY_LEN); + for (j = 0; j < key_size; j++) + key_buf[j] = key_data[j] ^ i; + ARC4_set_key(&key, key_size, key_buf); + ARC4(&key, MAX_KEY_LEN, in_buf, out_buf); + } + break; + default: + ERROR("Invalid revision number.\n"); + } + + memcpy(upwd_string, out_buf, MAX_STR_LEN); +} + +#ifdef WIN32 +static char *getpass (const char *prompt) +{ + static char pwd_buf[128]; + size_t i; + + fputs(prompt, stderr); + fflush(stderr); + for (i = 0; i < sizeof(pwd_buf)-1; i++) { + pwd_buf[i] = getch(); + if (pwd_buf[i] == '\r') + break; + fputs("*", stderr); + fflush(stderr); + } + pwd_buf[i] = '\0'; + fputs("\n", stderr); + return pwd_buf; +} +#endif + +void pdf_enc_set_passwd (unsigned bits, unsigned perm, const char *owner_pw, const char *user_pw) +{ + char *retry_passwd; + + if (owner_pw) { + strncpy(owner_passwd, owner_pw, MAX_PWD_LEN); + } else + while (1) { + strncpy(owner_passwd, getpass("Owner password: "), MAX_PWD_LEN); + retry_passwd = getpass("Re-enter owner password: "); + if (!strncmp(owner_passwd, retry_passwd, MAX_PWD_LEN)) + break; + fputs("Password is not identical.\nTry again.\n", stderr); + fflush(stderr); + } + + if (user_pw) { + strncpy(user_passwd, user_pw, MAX_PWD_LEN); + } else + while (1) { + strncpy(user_passwd, getpass("User password: "), MAX_PWD_LEN); + retry_passwd = getpass("Re-enter user password: "); + if (!strncmp(user_passwd, retry_passwd, MAX_PWD_LEN)) + break; + fputs("Password is not identical.\nTry again.\n", stderr); + fflush(stderr); + } + + key_size = (unsigned char)(bits / 8); + algorithm = (key_size == 5 ? 1 : 2); + permission = (unsigned long)perm | 0x000000C0; + revision = ((algorithm == 1 && permission < 0x100) ? 2 : 3); + if (revision == 3) + permission |= 0xFFFFF000; + + compute_owner_password(); + compute_user_password(); +} + +void pdf_encrypt_data (unsigned char *data, unsigned long len) +{ + unsigned char *result; + + memcpy(in_buf, key_data, key_size); + in_buf[key_size] = (unsigned char)(current_label) & 0xFF; + in_buf[key_size+1] = (unsigned char)(current_label >> 8) & 0xFF; + in_buf[key_size+2] = (unsigned char)(current_label >> 16) & 0xFF; + in_buf[key_size+3] = (unsigned char)(current_generation) & 0xFF; + in_buf[key_size+4] = (unsigned char)(current_generation >> 8) & 0xFF; + + MD5_init(&md5_ctx); + MD5_write(&md5_ctx, in_buf, key_size+5); + MD5_final(md5_buf, &md5_ctx); + + result = NEW (len, unsigned char); + ARC4_set_key(&key, (key_size > 10 ? MAX_KEY_LEN : key_size+5), md5_buf); + ARC4(&key, len, data, result); + memcpy(data, result, len); + RELEASE (result); +} + +pdf_obj *pdf_encrypt_obj (void) +{ + pdf_obj *doc_encrypt; + +#ifdef DEBUG + fprintf (stderr, "(pdf_encrypt_obj)"); +#endif + + doc_encrypt = pdf_new_dict (); + + /* KEY : Filter + * TYPE : name + * VALUE: (Required) The name of the security handler for this document; + * see below. Default value: Standard, for the built-in security + * handler. + */ + pdf_add_dict (doc_encrypt, + pdf_new_name ("Filter"), + pdf_new_name ("Standard")); + /* KEY : V + * TYPE : number + * VALUE: (Optional but strongly recommended) A code specifying the + * algorithm to be used in encrypting and decrypting the document: + * 0 An algorithm that is undocumented and no longer supported, + * and whose use is strongly discouraged. + * 1 Algorithm 3.1 on page 73, with an encryption key length + * of 40 bits; see below. + * 2 (PDF 1.4) Algorithm 3.1 on page 73, but allowing encryption + * key lengths greater than 40 bits. + * 3 (PDF 1.4) An unpublished algorithm allowing encryption key + * lengths ranging from 40 to 128 bits. (This algorithm is + * unpublished as an export requirement of the U.S. Department + * of Commerce.) + * The default value if this entry is omitted is 0, but a value + * of 1 or greater is strongly recommended. + */ + pdf_add_dict (doc_encrypt, + pdf_new_name ("V"), + pdf_new_number (algorithm)); + /* KEY : Length + * TYPE : integer + * VALUE: (Optional; PDF 1.4; only if V is 2 or 3) The length of the + * encryption key, in bits. The value must be a multiple of 8, + * in the range 40 to 128. Default value: 40. + */ + if (algorithm > 1) + pdf_add_dict (doc_encrypt, + pdf_new_name ("Length"), + pdf_new_number (key_size * 8)); + /* KEY : R + * TYPE : number + * VALUE: (Required) A number specifying which revision of the standard + * security handler should be used to interpret this dictionary. + * The revison number should be 2 if the document is encrypted + * with a V value less than 2; otherwise this value should be 3. + */ + pdf_add_dict (doc_encrypt, + pdf_new_name ("R"), + pdf_new_number (revision)); + /* KEY : O + * TYPE : string + * VALUE: (Required) A 32-byte string, based on both the owner and + * user passwords, that is used in computing the encryption + * key and in determining whether a valid owner password was + * entered. + */ + pdf_add_dict (doc_encrypt, + pdf_new_name ("O"), + pdf_new_string (opwd_string, 32)); + /* KEY : U + * TYPE : string + * VALUE: (Required) A 32-byte string, based on the user password, + * that is used in determining whether to prompt the user + * for a password and, if so, whether a valid user or owner + * password was entered. + */ + pdf_add_dict (doc_encrypt, + pdf_new_name ("U"), + pdf_new_string (upwd_string, 32)); + /* KEY : P + * TYPE : integer + * VALUE: (Required) A set of flags specifying which operations are + * permitted when the document is opened with user access. + */ + pdf_add_dict (doc_encrypt, + pdf_new_name ("P"), + pdf_new_number (permission)); + + return doc_encrypt; +} + +pdf_obj *pdf_enc_id_array (void) +{ + pdf_obj *id = pdf_new_array(); + pdf_add_array(id, pdf_new_string(id_string, MAX_KEY_LEN)); + pdf_add_array(id, pdf_new_string(id_string, MAX_KEY_LEN)); + return id; +} + +void pdf_enc_set_label (unsigned long label) +{ + current_label = label; +} + +void pdf_enc_set_generation (unsigned generation) +{ + current_generation = generation; +} |