5 EVP_MD_CTX_init, EVP_MD_CTX_create, EVP_DigestInit_ex, EVP_DigestUpdate,
6 EVP_DigestFinal_ex, EVP_MD_CTX_cleanup, EVP_MD_CTX_destroy, EVP_MAX_MD_SIZE,
7 EVP_MD_CTX_copy_ex, EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size,
8 EVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size, EVP_MD_CTX_block_size, EVP_MD_CTX_type,
9 EVP_md_null, EVP_md2, EVP_md5, EVP_sha, EVP_sha1, EVP_dss, EVP_dss1, EVP_mdc2,
10 EVP_ripemd160, EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj -
15 #include <openssl/evp.h>
17 void EVP_MD_CTX_init(EVP_MD_CTX *ctx);
18 EVP_MD_CTX *EVP_MD_CTX_create(void);
20 int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
21 int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
22 int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md,
25 int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx);
26 void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx);
28 int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out,const EVP_MD_CTX *in);
30 int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
31 int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md,
34 int EVP_MD_CTX_copy(EVP_MD_CTX *out,EVP_MD_CTX *in);
36 #define EVP_MAX_MD_SIZE (16+20) /* The SSLv3 md5+sha1 type */
39 #define EVP_MD_type(e) ((e)->type)
40 #define EVP_MD_pkey_type(e) ((e)->pkey_type)
41 #define EVP_MD_size(e) ((e)->md_size)
42 #define EVP_MD_block_size(e) ((e)->block_size)
44 #define EVP_MD_CTX_md(e) (e)->digest)
45 #define EVP_MD_CTX_size(e) EVP_MD_size((e)->digest)
46 #define EVP_MD_CTX_block_size(e) EVP_MD_block_size((e)->digest)
47 #define EVP_MD_CTX_type(e) EVP_MD_type((e)->digest)
49 const EVP_MD *EVP_md_null(void);
50 const EVP_MD *EVP_md2(void);
51 const EVP_MD *EVP_md5(void);
52 const EVP_MD *EVP_sha(void);
53 const EVP_MD *EVP_sha1(void);
54 const EVP_MD *EVP_dss(void);
55 const EVP_MD *EVP_dss1(void);
56 const EVP_MD *EVP_mdc2(void);
57 const EVP_MD *EVP_ripemd160(void);
59 const EVP_MD *EVP_get_digestbyname(const char *name);
60 #define EVP_get_digestbynid(a) EVP_get_digestbyname(OBJ_nid2sn(a))
61 #define EVP_get_digestbyobj(a) EVP_get_digestbynid(OBJ_obj2nid(a))
65 The EVP digest routines are a high level interface to message digests.
67 EVP_MD_CTX_init() initializes digest contet B<ctx>.
69 EVP_MD_CTX_create() allocates, initializes and returns a digest contet.
71 EVP_DigestInit_ex() sets up digest context B<ctx> to use a digest
72 B<type> from ENGINE B<impl>. B<ctx> must be initialized before calling this
73 function. B<type> will typically be supplied by a functionsuch as EVP_sha1().
74 If B<impl> is NULL then the default implementation of digest B<type> is used.
76 EVP_DigestUpdate() hashes B<cnt> bytes of data at B<d> into the
77 digest context B<ctx>. This function can be called several times on the
78 same B<ctx> to hash additional data.
80 EVP_DigestFinal_ex() retrieves the digest value from B<ctx> and places
81 it in B<md>. If the B<s> parameter is not NULL then the number of
82 bytes of data written (i.e. the length of the digest) will be written
83 to the integer at B<s>, at most B<EVP_MAX_MD_SIZE> bytes will be written.
84 After calling EVP_DigestFinal_ex() no additional calls to EVP_DigestUpdate()
85 can be made, but EVP_DigestInit_ex() can be called to initialize a new
88 EVP_MD_CTX_cleanup() cleans up digest context B<ctx>, it should be called
89 after a digest context is no longer needed.
91 EVP_MD_CTX_destroy() cleans up digest context B<ctx> and frees up the
92 space allocated to it, it should be called only on a context created
93 using EVP_MD_CTX_create().
95 EVP_MD_CTX_copy_ex() can be used to copy the message digest state from
96 B<in> to B<out>. This is useful if large amounts of data are to be
97 hashed which only differ in the last few bytes. B<out> must be initialized
98 before calling this function.
100 EVP_DigestInit() behaves in the same way as EVP_DigestInit_ex() except
101 the passed context B<ctx> does not have to be initialized, and it always
102 uses the default digest implementation.
104 EVP_DigestFinal() is similar to EVP_DigestFinal_ex() except the digest
105 contet B<ctx> is automatically cleaned up.
107 EVP_MD_CTX_copy() is similar to EVP_MD_CTX_copy_ex() except the destination
108 B<out> does not have to be initialized.
110 EVP_MD_size() and EVP_MD_CTX_size() return the size of the message digest
111 when passed an B<EVP_MD> or an B<EVP_MD_CTX> structure, i.e. the size of the
114 EVP_MD_block_size() and EVP_MD_CTX_block_size() return the block size of the
115 message digest when passed an B<EVP_MD> or an B<EVP_MD_CTX> structure.
117 EVP_MD_type() and EVP_MD_CTX_type() return the NID of the OBJECT IDENTIFIER
118 representing the given message digest when passed an B<EVP_MD> structure.
119 For example EVP_MD_type(EVP_sha1()) returns B<NID_sha1>. This function is
120 normally used when setting ASN1 OIDs.
122 EVP_MD_CTX_md() returns the B<EVP_MD> structure corresponding to the passed
125 EVP_MD_pkey_type() returns the NID of the public key signing algorithm associated
126 with this digest. For example EVP_sha1() is associated with RSA so this will
127 return B<NID_sha1WithRSAEncryption>. This "link" between digests and signature
128 algorithms may not be retained in future versions of OpenSSL.
130 EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_mdc2() and EVP_ripemd160()
131 return B<EVP_MD> structures for the MD2, MD5, SHA, SHA1, MDC2 and RIPEMD160 digest
132 algorithms respectively. The associated signature algorithm is RSA in each case.
134 EVP_dss() and EVP_dss1() return B<EVP_MD> structures for SHA and SHA1 digest
135 algorithms but using DSS (DSA) for the signature algorithm.
137 EVP_md_null() is a "null" message digest that does nothing: i.e. the hash it
138 returns is of zero length.
140 EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj()
141 return an B<EVP_MD> structure when passed a digest name, a digest NID or
142 an ASN1_OBJECT structure respectively. The digest table must be initialized
143 using, for example, OpenSSL_add_all_digests() for these functions to work.
147 EVP_DigestInit_ex(), EVP_DigestUpdate() and EVP_DigestFinal_ex() return 1 for
148 success and 0 for failure.
150 EVP_MD_CTX_copy_ex() returns 1 if successful or 0 for failure.
152 EVP_MD_type(), EVP_MD_pkey_type() and EVP_MD_type() return the NID of the
153 corresponding OBJECT IDENTIFIER or NID_undef if none exists.
155 EVP_MD_size(), EVP_MD_block_size(), EVP_MD_CTX_size(e), EVP_MD_size(),
156 EVP_MD_CTX_block_size() and EVP_MD_block_size() return the digest or block
159 EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_dss(),
160 EVP_dss1(), EVP_mdc2() and EVP_ripemd160() return pointers to the
161 corresponding EVP_MD structures.
163 EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj()
164 return either an B<EVP_MD> structure or NULL if an error occurs.
168 The B<EVP> interface to message digests should almost always be used in
169 preference to the low level interfaces. This is because the code then becomes
170 transparent to the digest used and much more flexible.
172 SHA1 is the digest of choice for new applications. The other digest algorithms
173 are still in common use.
175 For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
176 set to NULL to use the default digest implementation.
178 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
179 obsolete but are retained to maintain compatibility with existing code. New
180 applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
181 EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
182 instead of initializing and cleaning it up on each call and allow non default
183 implementations of digests to be specified.
185 In OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use
186 memory leaks will occur.
190 This example digests the data "Test Message\n" and "Hello World\n", using the
191 digest name passed on the command line.
194 #include <openssl/evp.h>
196 main(int argc, char *argv[])
200 char mess1[] = "Test Message\n";
201 char mess2[] = "Hello World\n";
202 unsigned char md_value[EVP_MAX_MD_SIZE];
205 OpenSSL_add_all_digests();
208 printf("Usage: mdtest digestname\n");
212 md = EVP_get_digestbyname(argv[1]);
215 printf("Unknown message digest %s\n", argv[1]);
219 EVP_MD_CTX_init(&mdctx);
220 EVP_DigestInit_ex(&mdctx, md, NULL);
221 EVP_DigestUpdate(&mdctx, mess1, strlen(mess1));
222 EVP_DigestUpdate(&mdctx, mess2, strlen(mess2));
223 EVP_DigestFinal_ex(&mdctx, md_value, &md_len);
224 EVP_MD_CTX_cleanup(&mdctx);
226 printf("Digest is: ");
227 for(i = 0; i < md_len; i++) printf("%02x", md_value[i]);
233 The link between digests and signing algorithms results in a situation where
234 EVP_sha1() must be used with RSA and EVP_dss1() must be used with DSS
235 even though they are identical digests.
239 L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
240 L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,
241 L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)>
245 EVP_DigestInit(), EVP_DigestUpdate() and EVP_DigestFinal() are
246 available in all versions of SSLeay and OpenSSL.
248 EVP_MD_CTX_init(), EVP_MD_CTX_create(), EVP_MD_CTX_copy_ex(),
249 EVP_MD_CTX_cleanup(), EVP_MD_CTX_destroy(), EVP_DigestInit_ex()
250 and EVP_DigestFinal_ex() were added in OpenSSL 0.9.7.
252 EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(),
253 EVP_dss(), EVP_dss1(), EVP_mdc2() and EVP_ripemd160() were
254 changed to return truely const EVP_MD * in OpenSSL 0.9.7.