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Diffstat (limited to 'src/lib/libcrypto/doc/EVP_DigestInit.pod')
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diff --git a/src/lib/libcrypto/doc/EVP_DigestInit.pod b/src/lib/libcrypto/doc/EVP_DigestInit.pod new file mode 100644 index 0000000000..236e2fa8d1 --- /dev/null +++ b/src/lib/libcrypto/doc/EVP_DigestInit.pod | |||
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| 1 | =pod | ||
| 2 | |||
| 3 | =head1 NAME | ||
| 4 | |||
| 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 - | ||
| 11 | EVP digest routines | ||
| 12 | |||
| 13 | =head1 SYNOPSIS | ||
| 14 | |||
| 15 | #include <openssl/evp.h> | ||
| 16 | |||
| 17 | void EVP_MD_CTX_init(EVP_MD_CTX *ctx); | ||
| 18 | EVP_MD_CTX *EVP_MD_CTX_create(void); | ||
| 19 | |||
| 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, | ||
| 23 | unsigned int *s); | ||
| 24 | |||
| 25 | int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx); | ||
| 26 | void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx); | ||
| 27 | |||
| 28 | int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out,const EVP_MD_CTX *in); | ||
| 29 | |||
| 30 | int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type); | ||
| 31 | int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, | ||
| 32 | unsigned int *s); | ||
| 33 | |||
| 34 | int EVP_MD_CTX_copy(EVP_MD_CTX *out,EVP_MD_CTX *in); | ||
| 35 | |||
| 36 | #define EVP_MAX_MD_SIZE (16+20) /* The SSLv3 md5+sha1 type */ | ||
| 37 | |||
| 38 | |||
| 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) | ||
| 43 | |||
| 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) | ||
| 48 | |||
| 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); | ||
| 58 | |||
| 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)) | ||
| 62 | |||
| 63 | =head1 DESCRIPTION | ||
| 64 | |||
| 65 | The EVP digest routines are a high level interface to message digests. | ||
| 66 | |||
| 67 | EVP_MD_CTX_init() initializes digest contet B<ctx>. | ||
| 68 | |||
| 69 | EVP_MD_CTX_create() allocates, initializes and returns a digest contet. | ||
| 70 | |||
| 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. | ||
| 75 | |||
| 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. | ||
| 79 | |||
| 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 | ||
| 86 | digest operation. | ||
| 87 | |||
| 88 | EVP_MD_CTX_cleanup() cleans up digest context B<ctx>, it should be called | ||
| 89 | after a digest context is no longer needed. | ||
| 90 | |||
| 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(). | ||
| 94 | |||
| 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. | ||
| 99 | |||
| 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. | ||
| 103 | |||
| 104 | EVP_DigestFinal() is similar to EVP_DigestFinal_ex() except the digest | ||
| 105 | contet B<ctx> is automatically cleaned up. | ||
| 106 | |||
| 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. | ||
| 109 | |||
| 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 | ||
| 112 | hash. | ||
| 113 | |||
| 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. | ||
| 116 | |||
| 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. | ||
| 121 | |||
| 122 | EVP_MD_CTX_md() returns the B<EVP_MD> structure corresponding to the passed | ||
| 123 | B<EVP_MD_CTX>. | ||
| 124 | |||
| 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. | ||
| 129 | |||
| 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. | ||
| 133 | |||
| 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. | ||
| 136 | |||
| 137 | EVP_md_null() is a "null" message digest that does nothing: i.e. the hash it | ||
| 138 | returns is of zero length. | ||
| 139 | |||
| 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. | ||
| 144 | |||
| 145 | =head1 RETURN VALUES | ||
| 146 | |||
| 147 | EVP_DigestInit_ex(), EVP_DigestUpdate() and EVP_DigestFinal_ex() return 1 for | ||
| 148 | success and 0 for failure. | ||
| 149 | |||
| 150 | EVP_MD_CTX_copy_ex() returns 1 if successful or 0 for failure. | ||
| 151 | |||
| 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. | ||
| 154 | |||
| 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 | ||
| 157 | size in bytes. | ||
| 158 | |||
| 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. | ||
| 162 | |||
| 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. | ||
| 165 | |||
| 166 | =head1 NOTES | ||
| 167 | |||
| 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. | ||
| 171 | |||
| 172 | SHA1 is the digest of choice for new applications. The other digest algorithms | ||
| 173 | are still in common use. | ||
| 174 | |||
| 175 | For most applications the B<impl> parameter to EVP_DigestInit_ex() will be | ||
| 176 | set to NULL to use the default digest implementation. | ||
| 177 | |||
| 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. | ||
| 184 | |||
| 185 | In OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use | ||
| 186 | memory leaks will occur. | ||
| 187 | |||
| 188 | =head1 EXAMPLE | ||
| 189 | |||
| 190 | This example digests the data "Test Message\n" and "Hello World\n", using the | ||
| 191 | digest name passed on the command line. | ||
| 192 | |||
| 193 | #include <stdio.h> | ||
| 194 | #include <openssl/evp.h> | ||
| 195 | |||
| 196 | main(int argc, char *argv[]) | ||
| 197 | { | ||
| 198 | EVP_MD_CTX mdctx; | ||
| 199 | const EVP_MD *md; | ||
| 200 | char mess1[] = "Test Message\n"; | ||
| 201 | char mess2[] = "Hello World\n"; | ||
| 202 | unsigned char md_value[EVP_MAX_MD_SIZE]; | ||
| 203 | int md_len, i; | ||
| 204 | |||
| 205 | OpenSSL_add_all_digests(); | ||
| 206 | |||
| 207 | if(!argv[1]) { | ||
| 208 | printf("Usage: mdtest digestname\n"); | ||
| 209 | exit(1); | ||
| 210 | } | ||
| 211 | |||
| 212 | md = EVP_get_digestbyname(argv[1]); | ||
| 213 | |||
| 214 | if(!md) { | ||
| 215 | printf("Unknown message digest %s\n", argv[1]); | ||
| 216 | exit(1); | ||
| 217 | } | ||
| 218 | |||
| 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); | ||
| 225 | |||
| 226 | printf("Digest is: "); | ||
| 227 | for(i = 0; i < md_len; i++) printf("%02x", md_value[i]); | ||
| 228 | printf("\n"); | ||
| 229 | } | ||
| 230 | |||
| 231 | =head1 BUGS | ||
| 232 | |||
| 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. | ||
| 236 | |||
| 237 | =head1 SEE ALSO | ||
| 238 | |||
| 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<RIPEMD160(3)|RIPEMD160(3)>, | ||
| 241 | L<SHA1(3)|SHA1(3)> | ||
| 242 | |||
| 243 | =head1 HISTORY | ||
| 244 | |||
| 245 | EVP_DigestInit(), EVP_DigestUpdate() and EVP_DigestFinal() are | ||
| 246 | available in all versions of SSLeay and OpenSSL. | ||
| 247 | |||
| 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. | ||
| 251 | |||
| 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. | ||
| 255 | |||
| 256 | =cut | ||
