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Diffstat (limited to 'examples/decrypt3.c')
-rw-r--r-- | examples/decrypt3.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/examples/decrypt3.c b/examples/decrypt3.c new file mode 100644 index 00000000..253920fb --- /dev/null +++ b/examples/decrypt3.c @@ -0,0 +1,372 @@ +/** + * XML Security Library example: Decrypting an encrypted file using a custom keys manager. + * + * Decrypts encrypted XML file using a custom files based keys manager. + * We assume that key's name in <dsig:KeyName/> element is just + * key's file name in the current folder. + * + * Usage: + * ./decrypt3 <xml-enc> + * + * Example: + * ./decrypt3 encrypt1-res.xml + * ./decrypt3 encrypt2-res.xml + * + * This is free software; see Copyright file in the source + * distribution for preciese wording. + * + * Copyright (C) 2002-2003 Aleksey Sanin <aleksey@aleksey.com> + */ +#include <stdlib.h> +#include <string.h> +#include <ctype.h> +#include <assert.h> + +#include <libxml/tree.h> +#include <libxml/xmlmemory.h> +#include <libxml/parser.h> + +#ifndef XMLSEC_NO_XSLT +#include <libxslt/xslt.h> +#include <libxslt/security.h> +#endif /* XMLSEC_NO_XSLT */ + +#include <xmlsec/xmlsec.h> +#include <xmlsec/xmltree.h> +#include <xmlsec/xmlenc.h> +#include <xmlsec/crypto.h> + +xmlSecKeyStoreId files_keys_store_get_klass(void); +xmlSecKeysMngrPtr create_files_keys_mngr(void); +int decrypt_file(xmlSecKeysMngrPtr mngr, const char* enc_file); + +int +main(int argc, char **argv) { + xmlSecKeysMngrPtr mngr; +#ifndef XMLSEC_NO_XSLT + xsltSecurityPrefsPtr xsltSecPrefs = NULL; +#endif /* XMLSEC_NO_XSLT */ + + assert(argv); + + if(argc != 2) { + fprintf(stderr, "Error: wrong number of arguments.\n"); + fprintf(stderr, "Usage: %s <enc-file>\n", argv[0]); + return(1); + } + + /* Init libxml and libxslt libraries */ + xmlInitParser(); + LIBXML_TEST_VERSION + xmlLoadExtDtdDefaultValue = XML_DETECT_IDS | XML_COMPLETE_ATTRS; + xmlSubstituteEntitiesDefault(1); +#ifndef XMLSEC_NO_XSLT + xmlIndentTreeOutput = 1; +#endif /* XMLSEC_NO_XSLT */ + + /* Init libxslt */ +#ifndef XMLSEC_NO_XSLT + /* disable everything */ + xsltSecPrefs = xsltNewSecurityPrefs(); + xsltSetSecurityPrefs(xsltSecPrefs, XSLT_SECPREF_READ_FILE, xsltSecurityForbid); + xsltSetSecurityPrefs(xsltSecPrefs, XSLT_SECPREF_WRITE_FILE, xsltSecurityForbid); + xsltSetSecurityPrefs(xsltSecPrefs, XSLT_SECPREF_CREATE_DIRECTORY, xsltSecurityForbid); + xsltSetSecurityPrefs(xsltSecPrefs, XSLT_SECPREF_READ_NETWORK, xsltSecurityForbid); + xsltSetSecurityPrefs(xsltSecPrefs, XSLT_SECPREF_WRITE_NETWORK, xsltSecurityForbid); + xsltSetDefaultSecurityPrefs(xsltSecPrefs); +#endif /* XMLSEC_NO_XSLT */ + + /* Init xmlsec library */ + if(xmlSecInit() < 0) { + fprintf(stderr, "Error: xmlsec initialization failed.\n"); + return(-1); + } + + /* Check loaded library version */ + if(xmlSecCheckVersion() != 1) { + fprintf(stderr, "Error: loaded xmlsec library version is not compatible.\n"); + return(-1); + } + + /* Load default crypto engine if we are supporting dynamic + * loading for xmlsec-crypto libraries. Use the crypto library + * name ("openssl", "nss", etc.) to load corresponding + * xmlsec-crypto library. + */ +#ifdef XMLSEC_CRYPTO_DYNAMIC_LOADING + if(xmlSecCryptoDLLoadLibrary(BAD_CAST XMLSEC_CRYPTO) < 0) { + fprintf(stderr, "Error: unable to load default xmlsec-crypto library. Make sure\n" + "that you have it installed and check shared libraries path\n" + "(LD_LIBRARY_PATH) envornment variable.\n"); + return(-1); + } +#endif /* XMLSEC_CRYPTO_DYNAMIC_LOADING */ + + /* Init crypto library */ + if(xmlSecCryptoAppInit(NULL) < 0) { + fprintf(stderr, "Error: crypto initialization failed.\n"); + return(-1); + } + + /* Init xmlsec-crypto library */ + if(xmlSecCryptoInit() < 0) { + fprintf(stderr, "Error: xmlsec-crypto initialization failed.\n"); + return(-1); + } + + /* create keys manager and load keys */ + mngr = create_files_keys_mngr(); + if(mngr == NULL) { + return(-1); + } + + if(decrypt_file(mngr, argv[1]) < 0) { + xmlSecKeysMngrDestroy(mngr); + return(-1); + } + + /* destroy keys manager */ + xmlSecKeysMngrDestroy(mngr); + + /* Shutdown xmlsec-crypto library */ + xmlSecCryptoShutdown(); + + /* Shutdown crypto library */ + xmlSecCryptoAppShutdown(); + + /* Shutdown xmlsec library */ + xmlSecShutdown(); + + /* Shutdown libxslt/libxml */ +#ifndef XMLSEC_NO_XSLT + xsltFreeSecurityPrefs(xsltSecPrefs); + xsltCleanupGlobals(); +#endif /* XMLSEC_NO_XSLT */ + xmlCleanupParser(); + + return(0); +} + +/** + * decrypt_file: + * @mngr: the pointer to keys manager. + * @enc_file: the encrypted XML file name. + * + * Decrypts the XML file #enc_file using DES key from #key_file and + * prints results to stdout. + * + * Returns 0 on success or a negative value if an error occurs. + */ +int +decrypt_file(xmlSecKeysMngrPtr mngr, const char* enc_file) { + xmlDocPtr doc = NULL; + xmlNodePtr node = NULL; + xmlSecEncCtxPtr encCtx = NULL; + int res = -1; + + assert(mngr); + assert(enc_file); + + /* load template */ + doc = xmlParseFile(enc_file); + if ((doc == NULL) || (xmlDocGetRootElement(doc) == NULL)){ + fprintf(stderr, "Error: unable to parse file \"%s\"\n", enc_file); + goto done; + } + + /* find start node */ + node = xmlSecFindNode(xmlDocGetRootElement(doc), xmlSecNodeEncryptedData, xmlSecEncNs); + if(node == NULL) { + fprintf(stderr, "Error: start node not found in \"%s\"\n", enc_file); + goto done; + } + + /* create encryption context */ + encCtx = xmlSecEncCtxCreate(mngr); + if(encCtx == NULL) { + fprintf(stderr,"Error: failed to create encryption context\n"); + goto done; + } + + /* decrypt the data */ + if((xmlSecEncCtxDecrypt(encCtx, node) < 0) || (encCtx->result == NULL)) { + fprintf(stderr,"Error: decryption failed\n"); + goto done; + } + + /* print decrypted data to stdout */ + if(encCtx->resultReplaced != 0) { + fprintf(stdout, "Decrypted XML data:\n"); + xmlDocDump(stdout, doc); + } else { + fprintf(stdout, "Decrypted binary data (%d bytes):\n", xmlSecBufferGetSize(encCtx->result)); + if(xmlSecBufferGetData(encCtx->result) != NULL) { + fwrite(xmlSecBufferGetData(encCtx->result), + 1, + xmlSecBufferGetSize(encCtx->result), + stdout); + } + } + fprintf(stdout, "\n"); + + /* success */ + res = 0; + +done: + /* cleanup */ + if(encCtx != NULL) { + xmlSecEncCtxDestroy(encCtx); + } + + if(doc != NULL) { + xmlFreeDoc(doc); + } + return(res); +} + +/** + * create_files_keys_mngr: + * + * Creates a files based keys manager: we assume that key name is + * the key file name, + * + * Returns pointer to newly created keys manager or NULL if an error occurs. + */ +xmlSecKeysMngrPtr +create_files_keys_mngr(void) { + xmlSecKeyStorePtr keysStore; + xmlSecKeysMngrPtr mngr; + + /* create files based keys store */ + keysStore = xmlSecKeyStoreCreate(files_keys_store_get_klass()); + if(keysStore == NULL) { + fprintf(stderr, "Error: failed to create keys store.\n"); + return(NULL); + } + + /* create keys manager */ + mngr = xmlSecKeysMngrCreate(); + if(mngr == NULL) { + fprintf(stderr, "Error: failed to create keys manager.\n"); + xmlSecKeyStoreDestroy(keysStore); + return(NULL); + } + + /* add store to keys manager, from now on keys manager destroys the store if needed */ + if(xmlSecKeysMngrAdoptKeysStore(mngr, keysStore) < 0) { + fprintf(stderr, "Error: failed to add keys store to keys manager.\n"); + xmlSecKeyStoreDestroy(keysStore); + xmlSecKeysMngrDestroy(mngr); + return(NULL); + } + + /* initialize crypto library specific data in keys manager */ + if(xmlSecCryptoKeysMngrInit(mngr) < 0) { + fprintf(stderr, "Error: failed to initialize crypto data in keys manager.\n"); + xmlSecKeysMngrDestroy(mngr); + return(NULL); + } + + /* set the get key callback */ + mngr->getKey = xmlSecKeysMngrGetKey; + return(mngr); +} + +/**************************************************************************** + * + * Files Keys Store: we assume that key's name (content of the + * <dsig:KeyName/> element is a name of the file with a key (in the + * current folder). + * Attention: this probably not a good solution for high traffic systems. + * + ***************************************************************************/ +static xmlSecKeyPtr files_keys_store_find_key (xmlSecKeyStorePtr store, + const xmlChar* name, + xmlSecKeyInfoCtxPtr keyInfoCtx); +static xmlSecKeyStoreKlass files_keys_store_klass = { + sizeof(xmlSecKeyStoreKlass), + sizeof(xmlSecKeyStore), + BAD_CAST "files-based-keys-store", /* const xmlChar* name; */ + NULL, /* xmlSecKeyStoreInitializeMethod initialize; */ + NULL, /* xmlSecKeyStoreFinalizeMethod finalize; */ + files_keys_store_find_key, /* xmlSecKeyStoreFindKeyMethod findKey; */ + + /* reserved for the future */ + NULL, /* void* reserved0; */ + NULL, /* void* reserved1; */ +}; + +/** + * files_keys_store_get_klass: + * + * The files based keys store klass: we assume that key name is the + * key file name, + * + * Returns files based keys store klass. + */ +xmlSecKeyStoreId +files_keys_store_get_klass(void) { + return(&files_keys_store_klass); +} + +/** + * files_keys_store_find_key: + * @store: the pointer to simple keys store. + * @name: the desired key name. + * @keyInfoCtx: the pointer to <dsig:KeyInfo/> node processing context. + * + * Lookups key in the @store. The caller is responsible for destroying + * returned key with #xmlSecKeyDestroy function. + * + * Returns pointer to key or NULL if key not found or an error occurs. + */ +static xmlSecKeyPtr +files_keys_store_find_key(xmlSecKeyStorePtr store, const xmlChar* name, xmlSecKeyInfoCtxPtr keyInfoCtx) { + xmlSecKeyPtr key; + const xmlChar* p; + + assert(store); + assert(keyInfoCtx); + + /* it's possible to do not have the key name or desired key type + * but we could do nothing in this case */ + if((name == NULL) || (keyInfoCtx->keyReq.keyId == xmlSecKeyDataIdUnknown)){ + return(NULL); + } + + /* we don't want to open files in a folder other than "current"; + * to prevent it limit the characters in the key name to alpha/digit, + * '.', '-' or '_'. + */ + for(p = name; (*p) != '\0'; ++p) { + if(!isalnum((*p)) && ((*p) != '.') && ((*p) != '-') && ((*p) != '_')) { + return(NULL); + } + } + + if((keyInfoCtx->keyReq.keyId == xmlSecKeyDataDsaId) || (keyInfoCtx->keyReq.keyId == xmlSecKeyDataRsaId)) { + /* load key from a pem file, if key is not found then it's an error (is it?) */ + key = xmlSecCryptoAppKeyLoad(name, xmlSecKeyDataFormatPem, NULL, NULL, NULL); + if(key == NULL) { + fprintf(stderr,"Error: failed to load public pem key from \"%s\"\n", name); + return(NULL); + } + } else { + /* otherwise it's a binary key, if key is not found then it's an error (is it?) */ + key = xmlSecKeyReadBinaryFile(keyInfoCtx->keyReq.keyId, name); + if(key == NULL) { + fprintf(stderr,"Error: failed to load key from binary file \"%s\"\n", name); + return(NULL); + } + } + + /* set key name */ + if(xmlSecKeySetName(key, name) < 0) { + fprintf(stderr,"Error: failed to set key name for key from \"%s\"\n", name); + xmlSecKeyDestroy(key); + return(NULL); + } + + return(key); +} + |