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@@ -43,60 +43,60 @@ EVP_DigestInit, EVP_DigestUpdate, EVP_DigestFinal - EVP digest routines
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The EVP digest routines are a high level interface to message digests.
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B<EVP_DigestInit()> initialises a digest context B<ctx> to use a digest
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EVP_DigestInit() initialises a digest context B<ctx> to use a digest
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B<type>: this will typically be supplied by a function such as
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B<EVP_sha1()>.
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EVP_sha1().
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B<EVP_DigestUpdate()> hashes B<cnt> bytes of data at B<d> into the
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EVP_DigestUpdate() hashes B<cnt> bytes of data at B<d> into the
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digest context B<ctx>. This funtion can be called several times on the
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same B<ctx> to hash additional data.
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B<EVP_DigestFinal()> retrieves the digest value from B<ctx> and places
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EVP_DigestFinal() retrieves the digest value from B<ctx> and places
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it in B<md>. If the B<s> parameter is not NULL then the number of
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bytes of data written (i.e. the length of the digest) will be written
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to the integer at B<s>, at most B<EVP_MAX_MD_SIZE> bytes will be written.
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After calling B<EVP_DigestFinal> no additional calls to B<EVP_DigestUpdate>
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can be made, but B<EVP_DigestInit> can be called to initialiase a new
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After calling EVP_DigestFinal() no additional calls to EVP_DigestUpdate()
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can be made, but EVP_DigestInit() can be called to initialiase a new
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digest operation.
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B<EVP_MD_CTX_copy> can be used to copy the message digest state from
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EVP_MD_CTX_copy() can be used to copy the message digest state from
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B<in> to B<out>. This is useful if large amounts of data are to be
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hashed which only differ in the last few bytes.
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B<EVP_MD_size> and B<EVP_MD_CTX_size> return the size of the message digest
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EVP_MD_size() and EVP_MD_CTX_size() return the size of the message digest
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when passed an B<EVP_MD> or an B<EVP_MD_CTX> structure, i.e. the size of the
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hash.
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B<EVP_MD_block_size> and B<EVP_MD_CTX_block_size> return the block size of the
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EVP_MD_block_size() and EVP_MD_CTX_block_size() return the block size of the
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message digest when passed an B<EVP_MD> or an B<EVP_MD_CTX> structure.
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B<EVP_MD_type> and B<EVP_MD_CTX_type> return the NID of the OBJECT IDENTIFIER
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EVP_MD_type() and EVP_MD_CTX_type() return the NID of the OBJECT IDENTIFIER
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representing the given message digest when passed an B<EVP_MD> structure.
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For example B<EVP_MD_type(EVP_sha1())> returns B<NID_sha1>. This function is
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For example EVP_MD_type(EVP_sha1()) returns B<NID_sha1>. This function is
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normally used when setting ASN1 OIDs.
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B<EVP_MD_CTX_type> return the B<EVP_MD> structure corresponding to the passed
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EVP_MD_CTX_type() returns the B<EVP_MD> structure corresponding to the passed
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B<EVP_MD_CTX>.
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B<EVP_MD_pkey_type> returns the NID of the public key signing algorithm associated
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with this digest. For example B<EVP_sha1()> is associated with RSA so this will
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EVP_MD_pkey_type() returns the NID of the public key signing algorithm associated
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with this digest. For example EVP_sha1() is associated with RSA so this will
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return B<NID_sha1WithRSAEncryption>. This "link" between digests and signature
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algorithms may not be retained in future versions of OpenSSL.
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B<EVP_md2>, B<EVP_md5>, B<EVP_sha>, B<EVP_sha1>, B<EVP_mdc2> and B<EVP_ripemd160>
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EVP_md2(), EVP_md5(), EVP_sha(), EVP_sha1(), EVP_mdc2() and EVP_ripemd160()
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return B<EVP_MD> structures for the MD2, MD5, SHA, SHA1, MDC2 and RIPEMD160 digest
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algorithms respectively. The associated signature algorithm is RSA in each case.
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B<EVP_dss> and B<EVP_dss1> return B<EVP_MD> structures for SHA and SHA1 digest
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EVP_dss() and EVP_dss1() return B<EVP_MD> structures for SHA and SHA1 digest
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algorithms but using DSS (DSA) for the signature algorithm.
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B<EVP_md_null> is a "null" message digest that does nothing: i.e. the hash it
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EVP_md_null() is a "null" message digest that does nothing: i.e. the hash it
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returns is of zero length.
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B<EVP_get_digestbyname>, B<EVP_get_digestbynid> and B<EVP_get_digestbyobj>
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EVP_get_digestbyname(), EVP_get_digestbynid() and EVP_get_digestbyobj()
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return an B<EVP_MD> structure when passed a digest name, a digest NID or
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and ASN1_OBJECT structure respectively. The digest table must be initialised
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using, for example, B<OpenSSL_add_all_digests()> for these functions to work.
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using, for example, OpenSSL_add_all_digests() for these functions to work.
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=head1 RETURN VALUES
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@@ -178,7 +178,7 @@ internal digest operations will never fail some future hardware based operations
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might.
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The link between digests and signing algorithms results in a situation where
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B<EVP_sha1()> must be used with RSA and B<EVP_dss1()> must be used with DSS
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EVP_sha1() must be used with RSA and EVP_dss1() must be used with DSS
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even though they are identical digests.
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The size of an B<EVP_MD_CTX> structure is determined at compile time: this results
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@@ -186,6 +186,13 @@ in code that must be recompiled if the size of B<EVP_MD_CTX> increases.
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=head1 SEE ALSO
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L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
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L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,
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L<sha(3)|sha(3)>
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=head1 HISTORY
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EVP_DigestInit(), EVP_DigestUpdate() and EVP_DigestFinal() are
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available in all versions of SSLeay and OpenSSL.
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=cut
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