1SHA256_INIT(3)                      OpenSSL                     SHA256_INIT(3)
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NAME

6       SHA1, SHA1_Init, SHA1_Update, SHA1_Final, SHA224, SHA224_Init,
7       SHA224_Update, SHA224_Final, SHA256, SHA256_Init, SHA256_Update,
8       SHA256_Final, SHA384, SHA384_Init, SHA384_Update, SHA384_Final, SHA512,
9       SHA512_Init, SHA512_Update, SHA512_Final - Secure Hash Algorithm
10

SYNOPSIS

12        #include <openssl/sha.h>
13
14        int SHA1_Init(SHA_CTX *c);
15        int SHA1_Update(SHA_CTX *c, const void *data, size_t len);
16        int SHA1_Final(unsigned char *md, SHA_CTX *c);
17        unsigned char *SHA1(const unsigned char *d, size_t n,
18                            unsigned char *md);
19
20        int SHA224_Init(SHA256_CTX *c);
21        int SHA224_Update(SHA256_CTX *c, const void *data, size_t len);
22        int SHA224_Final(unsigned char *md, SHA256_CTX *c);
23        unsigned char *SHA224(const unsigned char *d, size_t n,
24                              unsigned char *md);
25
26        int SHA256_Init(SHA256_CTX *c);
27        int SHA256_Update(SHA256_CTX *c, const void *data, size_t len);
28        int SHA256_Final(unsigned char *md, SHA256_CTX *c);
29        unsigned char *SHA256(const unsigned char *d, size_t n,
30                              unsigned char *md);
31
32        int SHA384_Init(SHA512_CTX *c);
33        int SHA384_Update(SHA512_CTX *c, const void *data, size_t len);
34        int SHA384_Final(unsigned char *md, SHA512_CTX *c);
35        unsigned char *SHA384(const unsigned char *d, size_t n,
36                              unsigned char *md);
37
38        int SHA512_Init(SHA512_CTX *c);
39        int SHA512_Update(SHA512_CTX *c, const void *data, size_t len);
40        int SHA512_Final(unsigned char *md, SHA512_CTX *c);
41        unsigned char *SHA512(const unsigned char *d, size_t n,
42                              unsigned char *md);
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DESCRIPTION

45       Applications should use the higher level functions EVP_DigestInit(3)
46       etc. instead of calling the hash functions directly.
47
48       SHA-1 (Secure Hash Algorithm) is a cryptographic hash function with a
49       160 bit output.
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51       SHA1() computes the SHA-1 message digest of the n bytes at d and places
52       it in md (which must have space for SHA_DIGEST_LENGTH == 20 bytes of
53       output). If md is NULL, the digest is placed in a static array. Note:
54       setting md to NULL is not thread safe.
55
56       The following functions may be used if the message is not completely
57       stored in memory:
58
59       SHA1_Init() initializes a SHA_CTX structure.
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61       SHA1_Update() can be called repeatedly with chunks of the message to be
62       hashed (len bytes at data).
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64       SHA1_Final() places the message digest in md, which must have space for
65       SHA_DIGEST_LENGTH == 20 bytes of output, and erases the SHA_CTX.
66
67       The SHA224, SHA256, SHA384 and SHA512 families of functions operate in
68       the same way as for the SHA1 functions. Note that SHA224 and SHA256 use
69       a SHA256_CTX object instead of SHA_CTX. SHA384 and SHA512 use
70       SHA512_CTX.  The buffer md must have space for the output from the SHA
71       variant being used (defined by SHA224_DIGEST_LENGTH,
72       SHA256_DIGEST_LENGTH, SHA384_DIGEST_LENGTH and SHA512_DIGEST_LENGTH).
73       Also note that, as for the SHA1() function above, the SHA224(),
74       SHA256(), SHA384() and SHA512() functions are not thread safe if md is
75       NULL.
76
77       The predecessor of SHA-1, SHA, is also implemented, but it should be
78       used only when backward compatibility is required.
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RETURN VALUES

81       SHA1(), SHA224(), SHA256(), SHA384() and SHA512() return a pointer to
82       the hash value.
83
84       SHA1_Init(), SHA1_Update() and SHA1_Final() and equivalent SHA224,
85       SHA256, SHA384 and SHA512 functions return 1 for success, 0 otherwise.
86

CONFORMING TO

88       US Federal Information Processing Standard FIPS PUB 180-4 (Secure Hash
89       Standard), ANSI X9.30
90

SEE ALSO

92       EVP_DigestInit(3)
93

95       Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
96
97       Licensed under the OpenSSL license (the "License").  You may not use
98       this file except in compliance with the License.  You can obtain a copy
99       in the file LICENSE in the source distribution or at
100       <https://www.openssl.org/source/license.html>.
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1041.1.1c                            2019-05-28                    SHA256_INIT(3)
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