mirror of
https://github.com/openssl/openssl.git
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f7812493a0
Updates to include SHA224, SHA256, SHA384 and SHA512. In particular note the restriction on setting md to NULL with regards to thread safety. Reviewed-by: Tim Hudson <tjh@openssl.org>
100 lines
3.4 KiB
Plaintext
100 lines
3.4 KiB
Plaintext
=pod
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=head1 NAME
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SHA1, SHA1_Init, SHA1_Update, SHA1_Final, SHA224, SHA224_Init, SHA224_Update,
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SHA224_Final, SHA256, SHA256_Init, SHA256_Update, SHA256_Final, SHA384,
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SHA384_Init, SHA384_Update, SHA384_Final, SHA512, SHA512_Init, SHA512_Update,
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SHA512_Final - Secure Hash Algorithm
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=head1 SYNOPSIS
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#include <openssl/sha.h>
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int SHA1_Init(SHA_CTX *c);
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int SHA1_Update(SHA_CTX *c, const void *data, size_t len);
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int SHA1_Final(unsigned char *md, SHA_CTX *c);
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unsigned char *SHA1(const unsigned char *d, size_t n,
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unsigned char *md);
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int SHA224_Init(SHA256_CTX *c);
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int SHA224_Update(SHA256_CTX *c, const void *data, size_t len);
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int SHA224_Final(unsigned char *md, SHA256_CTX *c);
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unsigned char *SHA224(const unsigned char *d, size_t n,
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unsigned char *md);
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int SHA256_Init(SHA256_CTX *c);
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int SHA256_Update(SHA256_CTX *c, const void *data, size_t len);
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int SHA256_Final(unsigned char *md, SHA256_CTX *c);
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unsigned char *SHA256(const unsigned char *d, size_t n,
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unsigned char *md);
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int SHA384_Init(SHA512_CTX *c);
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int SHA384_Update(SHA512_CTX *c, const void *data, size_t len);
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int SHA384_Final(unsigned char *md, SHA512_CTX *c);
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unsigned char *SHA384(const unsigned char *d, size_t n,
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unsigned char *md);
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int SHA512_Init(SHA512_CTX *c);
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int SHA512_Update(SHA512_CTX *c, const void *data, size_t len);
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int SHA512_Final(unsigned char *md, SHA512_CTX *c);
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unsigned char *SHA512(const unsigned char *d, size_t n,
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unsigned char *md);
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=head1 DESCRIPTION
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Applications should use the higher level functions
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L<EVP_DigestInit(3)|EVP_DigestInit(3)> etc. instead of calling the hash
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functions directly.
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SHA-1 (Secure Hash Algorithm) is a cryptographic hash function with a
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160 bit output.
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SHA1() computes the SHA-1 message digest of the B<n>
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bytes at B<d> and places it in B<md> (which must have space for
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SHA_DIGEST_LENGTH == 20 bytes of output). If B<md> is NULL, the digest
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is placed in a static array. Note: setting B<md> to NULL is B<not thread safe>.
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The following functions may be used if the message is not completely
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stored in memory:
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SHA1_Init() initializes a B<SHA_CTX> structure.
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SHA1_Update() can be called repeatedly with chunks of the message to
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be hashed (B<len> bytes at B<data>).
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SHA1_Final() places the message digest in B<md>, which must have space
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for SHA_DIGEST_LENGTH == 20 bytes of output, and erases the B<SHA_CTX>.
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The SHA224, SHA256, SHA384 and SHA512 families of functions operate in the
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same way as for the SHA1 functions. Note that SHA224 and SHA256 use a
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B<SHA256_CTX> object instead of B<SHA_CTX>. SHA384 and SHA512 use B<SHA512_CTX>.
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The buffer B<md> must have space for the output from the SHA variant being used
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(defined by SHA224_DIGEST_LENGTH, SHA256_DIGEST_LENGTH, SHA384_DIGEST_LENGTH and
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SHA512_DIGEST_LENGTH). Also note that, as for the SHA1() function above, the
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SHA224(), SHA256(), SHA384() and SHA512() functions are not thread safe if
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B<md> is NULL.
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The predecessor of SHA-1, SHA, is also implemented, but it should be
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used only when backward compatibility is required.
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=head1 RETURN VALUES
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SHA1(), SHA224(), SHA256(), SHA384() and SHA512() return a pointer to the hash
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value.
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SHA1_Init(), SHA1_Update() and SHA1_Final() and equivalent SHA224, SHA256,
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SHA384 and SHA512 functions return 1 for success, 0 otherwise.
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=head1 CONFORMING TO
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US Federal Information Processing Standard FIPS PUB 180-4 (Secure Hash
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Standard),
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ANSI X9.30
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=head1 SEE ALSO
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L<EVP_DigestInit(3)|EVP_DigestInit(3)>
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=cut
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