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. Note: there is
136 no need to use these pseudo-digests in OpenSSL 1.0.0 and later, they are
137 however retained for compatibility.
139 EVP_md_null() is a "null" message digest that does nothing: i.e. the hash it
140 returns is of zero length.
142 EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj()
143 return an B<EVP_MD> structure when passed a digest name, a digest NID or
144 an ASN1_OBJECT structure respectively. The digest table must be initialized
145 using, for example, OpenSSL_add_all_digests() for these functions to work.
149 EVP_DigestInit_ex(), EVP_DigestUpdate() and EVP_DigestFinal_ex() return 1 for
150 success and 0 for failure.
152 EVP_MD_CTX_copy_ex() returns 1 if successful or 0 for failure.
154 EVP_MD_type(), EVP_MD_pkey_type() and EVP_MD_type() return the NID of the
155 corresponding OBJECT IDENTIFIER or NID_undef if none exists.
157 EVP_MD_size(), EVP_MD_block_size(), EVP_MD_CTX_size(e), EVP_MD_size(),
158 EVP_MD_CTX_block_size() and EVP_MD_block_size() return the digest or block
161 EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_dss(),
162 EVP_dss1(), EVP_mdc2() and EVP_ripemd160() return pointers to the
163 corresponding EVP_MD structures.
165 EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj()
166 return either an B<EVP_MD> structure or NULL if an error occurs.
170 The B<EVP> interface to message digests should almost always be used in
171 preference to the low level interfaces. This is because the code then becomes
172 transparent to the digest used and much more flexible.
174 SHA1 is the digest of choice for new applications. The other digest algorithms
175 are still in common use.
177 For most applications the B<impl> parameter to EVP_DigestInit_ex() will be
178 set to NULL to use the default digest implementation.
180 The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
181 obsolete but are retained to maintain compatibility with existing code. New
182 applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
183 EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
184 instead of initializing and cleaning it up on each call and allow non default
185 implementations of digests to be specified.
187 In OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use
188 memory leaks will occur.
192 This example digests the data "Test Message\n" and "Hello World\n", using the
193 digest name passed on the command line.
196 #include <openssl/evp.h>
198 main(int argc, char *argv[])
202 char mess1[] = "Test Message\n";
203 char mess2[] = "Hello World\n";
204 unsigned char md_value[EVP_MAX_MD_SIZE];
207 OpenSSL_add_all_digests();
210 printf("Usage: mdtest digestname\n");
214 md = EVP_get_digestbyname(argv[1]);
217 printf("Unknown message digest %s\n", argv[1]);
221 EVP_MD_CTX_init(&mdctx);
222 EVP_DigestInit_ex(&mdctx, md, NULL);
223 EVP_DigestUpdate(&mdctx, mess1, strlen(mess1));
224 EVP_DigestUpdate(&mdctx, mess2, strlen(mess2));
225 EVP_DigestFinal_ex(&mdctx, md_value, &md_len);
226 EVP_MD_CTX_cleanup(&mdctx);
228 printf("Digest is: ");
229 for(i = 0; i < md_len; i++) printf("%02x", md_value[i]);
235 L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
236 L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,
237 L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)>
241 EVP_DigestInit(), EVP_DigestUpdate() and EVP_DigestFinal() are
242 available in all versions of SSLeay and OpenSSL.
244 EVP_MD_CTX_init(), EVP_MD_CTX_create(), EVP_MD_CTX_copy_ex(),
245 EVP_MD_CTX_cleanup(), EVP_MD_CTX_destroy(), EVP_DigestInit_ex()
246 and EVP_DigestFinal_ex() were added in OpenSSL 0.9.7.
248 EVP_md_null(), EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(),
249 EVP_dss(), EVP_dss1(), EVP_mdc2() and EVP_ripemd160() were
250 changed to return truely const EVP_MD * in OpenSSL 0.9.7.
252 The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
253 later, so now EVP_sha1() can be used with RSA and DSA, there is no need to
254 use EVP_dss1() any more.
256 OpenSSL 1.0 and later does not include the MD2 digest algorithm in the
257 default configuration due to its security weaknesses.