BUFFER Library
==============================================================================
-[Note: I wrote this when I saw a Malloc version of strdup() in there which
- I'd written myself anyway. I was so annoyed at not noticing this I decided to
- document it :-) Steve.]
-
The buffer library handles simple character arrays. Buffers are used for various
purposes in the library, most notably memory BIOs.
The library uses the BUF_MEM structure defined in buffer.h:
typedef struct buf_mem_st
- {
+{
int length; /* current number of bytes */
char *data;
int max; /* size of buffer */
- } BUF_MEM;
+} BUF_MEM;
'length' is the current size of the buffer in bytes, 'max' is the amount of
memory allocated to the buffer. There are three functions which handle these
In each case the 'value' of the extension is placed directly in the extension.
Currently supported extensions in this category are: nsBaseUrl, nsRevocationUrl
-nsCaRevocationUrl, nsRenewalUrl, nsCaPolicyUrl, nsSslServerName and
-nsComment.
+nsCaRevocationUrl, nsRenewalUrl, nsCaPolicyUrl, nsSslServerName and nsComment.
For example:
NOTE: for a CA to be considered valid it must have the CA option set to
TRUE. An end user certificate MUST NOT have the CA value set to true.
-According to PKIX recommendations it should exclude the extension entirely
+According to PKIX recommendations it should exclude the extension entirely,
however some software may require CA set to FALSE for end entity certificates.
Subject Key Identifier.
but cannot be set. These include private key usage period, CRL number, and
CRL reason.
+==============================================================================
+ PKCS#12 Library
+==============================================================================
+
+This section describes the internal PKCS#12 support. There are very few
+differences between the old external library and the new internal code at
+present. This may well change because the external library will not be updated
+much in future.
+
+This version now includes a couple of high level PKCS#12 functions which
+generally "do the right thing" and should make it much easier to handle PKCS#12
+structures.
+
+HIGH LEVEL FUNCTIONS.
+
+For most applications you only need concern yourself with the high level
+functions. They can parse and generate simple PKCS#12 files as produced by
+Netscape and MSIE or indeed any compliant PKCS#12 file containing a single
+private key and certificate pair.
+
+1. Initialisation and cleanup.
+
+No special initialisation is needed for the internal PKCS#12 library: the
+standard SSLeay_add_all_algorithms() is sufficient. If you do not wish to
+add all algorithms then you can manually initialise the PKCS#12 library with:
+
+PKSC12_PBE_add();
+
+The memory allocated by the PKCS#12 libray is freed up when EVP_cleanup() is
+called or it can be directly freed with:
+
+EVP_PBE_cleanup();
+
+after this call (or EVP_cleanup() ) no more PKCS#12 library functions should
+be called.
+
+2. I/O functions.
+
+i2d_PKCS12_bio(bp, p12)
+
+This writes out a PKCS12 structure to a BIO.
+
+i2d_PKCS12_fp(fp, p12)
+
+This is the same but for a FILE pointer.
+
+d2i_PKCS12_bio(bp, p12)
+
+This reads in a PKCS12 structure from a BIO.
+
+d2i_PKCS12_fp(fp, p12)
+
+This is the same but for a FILE pointer.
+
+3. Parsing and creation functions.
+
+3.1 Parsing with PKCS12_parse().
+
+int PKCS12_parse(PKCS12 *p12, char *pass, EVP_PKEY **pkey, X509 **cert,
+ STACK **ca);
+
+This function takes a PKCS12 structure and a password (ASCII, null terminated)
+and returns the private key, the corresponding certificate and any CA
+certificates. If any of these is not required it can be passed as a NULL.
+The 'ca' parameter should be either NULL, a pointer to NULL or a valid STACK
+structure. Typically to read in a PKCS#12 file you might do:
+
+p12 = d2i_PKCS12_fp(fp, NULL);
+PKCS12_parse(p12, password, &pkey, &cert, NULL); /* CAs not wanted */
+PKCS12_free(p12);
+
+3.2 PKCS#12 creation with PKCS12_create().
+
+PKCS12 *PKCS12_create(char *pass, char *name, EVP_PKEY *pkey, X509 *cert,
+ STACK *ca, int nid_key, int nid_cert, int iter,
+ int mac_iter, int keytype);
+
+This function will create a PKCS12 structure from a given password, name,
+private key, certificate and optional STACK of CA certificates. The remaining
+5 parameters can be set to 0 and sensible defaults will be used.
+
+The parameters nid_key and nid_cert are the key and certificate encryption
+algorithms, iter is the encryption iteration count, mac_iter is the MAC
+iteration count and keytype is the type of private key. If you really want
+to know what these last 5 parameters do then read the low level section.
+
+Typically to create a PKCS#12 file the following could be used:
+
+p12 = PKCS12_create(pass, "My Certificate", pkey, cert, NULL, 0,0,0,0,0);
+i2d_PKCS12_fp(fp, p12);
+PKCS12_free(p12);
+
+LOW LEVEL FUNCTIONS.
+
+In some cases the high level functions do not provide the necessary
+functionality. For example if you want to generate or parse more complex PKCS#12
+files. The sample pkcs12 application uses the low level functions to display
+details about the internal structure of a PKCS#12 file.
+
+Introduction.
+
+This is a brief description of how a PKCS#12 file is represented internally:
+some knowledge of PKCS#12 is assumed.
+
+A PKCS#12 object contains several levels.
+
+At the lowest level is a PKCS12_SAFEBAG. This can contain a certificate, a
+CRL, a private key, encrypted or unencrypted, a set of safebags (so the
+structure can be nested) or other secrets (not documented at present).
+A safebag can optionally have attributes, currently these are: a unicode
+friendlyName (a Unicode string) or a localKeyID (a string of bytes).
+
+At the next level is an authSafe which is a set of safebags collected into
+a PKCS#7 ContentInfo. This can be just plain data, or encrypted itself.
+
+At the top level is the PKCS12 structure itself which contains a set of
+authSafes in an embedded PKCS#7 Contentinfo of type data. In addition it
+contains a MAC which is a kind of password protected digest to preserve
+integrity (so any unencrypted stuff below can't be tampered with).
+
+The reason for these levels is so various objects can be encrypted in various
+ways. For example you might want to encrypt a set of private keys with
+triple-DES and then include the related certificates either unencrypted or with
+lower encryption. Yes it's the dreaded crypto laws at work again which
+allow strong encryption on private keys and only weak encryption on other stuff.
+
+To build one of these things you turn all certificates and keys into safebags
+(with optional attributes). You collect the safebags into (one or more) STACKS
+and convert these into authsafes (encrypted or unencrypted). The authsafes are
+collected into a STACK and added to a PKCS12 structure. Finally a MAC inserted.
+
+Pulling one apart is basically the reverse process. The MAC is verified against
+the given password. The authsafes are extracted and each authsafe split into
+a set of safebags (possibly involving decryption). Finally the safebags are
+decomposed into the original keys and certificates and the attributes used to
+match up private key and certificate pairs.
+
+Anyway here are the functions that do the dirty work.
+
+1. Construction functions.
+
+1.1 Safebag functions.
+
+M_PKCS12_x5092certbag(x509)
+
+This macro takes an X509 structure and returns a certificate bag. The
+X509 structure can be freed up after calling this function.
+
+M_PKCS12_x509crl2certbag(crl)
+
+As above but for a CRL.
+
+PKCS8_PRIV_KEY_INFO *PKEY2PKCS8(EVP_PKEY *pkey)
+
+Take a private key and convert it into a PKCS#8 PrivateKeyInfo structure.
+Works for both RSA and DSA private keys. NB since the PKCS#8 PrivateKeyInfo
+structure contains a private key data in plain text form it should be free'd up
+as soon as it has been encrypted for security reasons (freeing up the structure
+zeros out the sensitive data). This can be done with PKCS8_PRIV_KEY_INFO_free().
+
+PKCS8_add_keyusage(PKCS8_PRIV_KEY_INFO *p8, int usage)
+
+This sets the key type when a key is imported into MSIE or Outlook 98. Two
+values are currently supported: KEY_EX and KEY_SIG. KEY_EX is an exchange type
+key that can also be used for signing but its size is limited in the export
+versions of MS software to 512 bits, it is also the default. KEY_SIG is a
+signing only key but the keysize is unlimited (well 16K is supposed to work).
+If you are using the domestic version of MSIE then you can ignore this because
+KEY_EX is not limited and can be used for both.
+
+PKCS12_SAFEBAG *PKCS12_MAKE_KEYBAG(PKCS8_PRIV_KEY_INFO *p8)
+
+Convert a PKCS8 private key structure into a keybag. This routine embeds the p8
+structure in the keybag so p8 should not be freed up or used after it is called.
+The p8 structure will be freed up when the safebag is freed.
+
+PKCS12_SAFEBAG *PKCS12_MAKE_SHKEYBAG(int pbe_nid, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, PKCS8_PRIV_KEY_INFO *p8)
+
+Convert a PKCS#8 structure into a shrouded key bag (encrypted). p8 is not
+embedded and can be freed up after use.
+
+int PKCS12_add_localkeyid(PKCS12_SAFEBAG *bag, unsigned char *name, int namelen)
+int PKCS12_add_friendlyname(PKCS12_SAFEBAG *bag, unsigned char *name, int namelen)
+
+Add a local key id or a friendlyname to a safebag.
+
+1.2 Authsafe functions.
+
+PKCS7 *PKCS12_pack_p7data(STACK *sk)
+Take a stack of safebags and convert them into an unencrypted authsafe. The
+stack of safebags can be freed up after calling this function.
+
+PKCS7 *PKCS12_pack_p7encdata(int pbe_nid, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, STACK *bags);
+
+As above but encrypted.
+
+1.3 PKCS12 functions.
+
+PKCS12 *PKCS12_init(int mode)
+
+Initialise a PKCS12 structure (currently mode should be NID_pkcs7_data).
+
+M_PKCS12_pack_authsafes(p12, safes)
+
+This macro takes a STACK of authsafes and adds them to a PKCS#12 structure.
+
+int PKCS12_set_mac(PKCS12 *p12, unsigned char *pass, int passlen, unsigned char *salt, int saltlen, int iter, EVP_MD *md_type);
+
+Add a MAC to a PKCS12 structure. If EVP_MD is NULL use SHA-1, the spec suggests
+that SHA-1 should be used.
+
+2. Extraction Functions.
+
+2.1 Safebags.
+
+M_PKCS12_bag_type(bag)
+
+Return the type of "bag". Returns one of the following
+
+NID_keyBag
+NID_pkcs8ShroudedKeyBag 7
+NID_certBag 8
+NID_crlBag 9
+NID_secretBag 10
+NID_safeContentsBag 11
+
+M_PKCS12_cert_bag_type(bag)
+
+Returns type of certificate bag, following are understood.
+
+NID_x509Certificate 14
+NID_sdsiCertificate 15
+
+M_PKCS12_crl_bag_type(bag)
+
+Returns crl bag type, currently only NID_crlBag is recognised.
+
+M_PKCS12_certbag2x509(bag)
+
+This macro extracts an X509 certificate from a certificate bag.
+
+M_PKCS12_certbag2x509crl(bag)
+
+As above but for a CRL.
+
+EVP_PKEY * PKCS82PKEY(PKCS8_PRIV_KEY_INFO *p8)
+
+Extract a private key from a PKCS8 private key info structure.
+
+M_PKCS12_decrypt_skey(bag, pass, passlen)
+
+Decrypt a shrouded key bag and return a PKCS8 private key info structure.
+Works with both RSA and DSA keys
+
+char *PKCS12_get_friendlyname(bag)
+
+Returns the friendlyName of a bag if present or NULL if none. The returned
+string is a null terminated ASCII string allocated with Malloc(). It should
+thus be freed up with Free() after use.
+
+2.2 AuthSafe functions.
+
+M_PKCS12_unpack_p7data(p7)
+
+Extract a STACK of safe bags from a PKCS#7 data ContentInfo.
+
+#define M_PKCS12_unpack_p7encdata(p7, pass, passlen)
+
+As above but for an encrypted content info.
+
+2.3 PKCS12 functions.
+
+M_PKCS12_unpack_authsafes(p12)
+
+Extract a STACK of authsafes from a PKCS12 structure.
+
+M_PKCS12_mac_present(p12)
+
+Check to see if a MAC is present.
+
+int PKCS12_verify_mac(PKCS12 *p12, unsigned char *pass, int passlen)
+
+Verify a MAC on a PKCS12 structure. Returns an error if MAC not present.
+
+
+Notes.
+
+1. All the function return 0 or NULL on error.
+2. Encryption based functions take a common set of parameters. These are
+described below.
+
+pass, passlen
+ASCII password and length. The password on the MAC is called the "integrity
+password" the encryption password is called the "privacy password" in the
+PKCS#12 documentation. The passwords do not have to be the same. If -1 is
+passed for the length it is worked out by the function itself (currently
+this is sometimes done whatever is passed as the length but that may change).
+
+salt, saltlen
+A 'salt' if salt is NULL a random salt is used. If saltlen is also zero a
+default length is used.
+
+iter
+Iteration count. This is a measure of how many times an internal function is
+called to encrypt the data. The larger this value is the longer it takes, it
+makes dictionary attacks on passwords harder. NOTE: Some implementations do
+not support an iteration count on the MAC. If the password for the MAC and
+encryption is the same then there is no point in having a high iteration
+count for encryption if the MAC has no count. The MAC could be attacked
+and the password used for the main decryption.
+
+pbe_nid
+This is the NID of the password based encryption method used. The following are
+supported.
+NID_pbe_WithSHA1And128BitRC4
+NID_pbe_WithSHA1And40BitRC4
+NID_pbe_WithSHA1And3_Key_TripleDES_CBC
+NID_pbe_WithSHA1And2_Key_TripleDES_CBC
+NID_pbe_WithSHA1And128BitRC2_CBC
+NID_pbe_WithSHA1And40BitRC2_CBC
+
+Which you use depends on the implementation you are exporting to. "Export grade"(i.e. cryptograhically challenged) products cannot support all algorithms.
+Typically you may be able to use any encryption on shrouded key bags but they
+must then be placed in an unencrypted authsafe. Other authsafes may only support
+40bit encryption. Of course if you are using SSLeay throughout you can strongly
+encrypt everything and have high iteration counts on everything.
+
+3. For decryption routines only the password and length are needed.
+
+4. Unlike the external version the nid's of objects are the values of the
+constants: that is NID_certBag is the real nid, therefore there is no
+PKCS12_obj_offset() function. Note the object constants are not the same as
+those of the external version. If you use these constants then you will need
+to recompile your code.
+
+5. With the exception of PKCS12_MAKE_KEYBAG(), after calling any function or
+macro of the form PKCS12_MAKE_SOMETHING(other) the "other" structure can be
+reused or freed up safely.
+
projects / openssl.git / blobdiff