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- =pod
- =head1 NAME
- SHA1, SHA1_Init, SHA1_Update, SHA1_Final - Secure Hash Algorithm
- =head1 SYNOPSIS
- #include <openssl/sha.h>
- unsigned char *SHA1(const unsigned char *d, unsigned long n,
- unsigned char *md);
- int SHA1_Init(SHA_CTX *c);
- int SHA1_Update(SHA_CTX *c, const void *data,
- unsigned long len);
- int SHA1_Final(unsigned char *md, SHA_CTX *c);
- =head1 DESCRIPTION
- SHA-1 (Secure Hash Algorithm) is a cryptographic hash function with a
- 160 bit output.
- SHA1() computes the SHA-1 message digest of the B<n>
- bytes at B<d> and places it in B<md> (which must have space for
- SHA_DIGEST_LENGTH == 20 bytes of output). If B<md> is NULL, the digest
- is placed in a static array.
- The following functions may be used if the message is not completely
- stored in memory:
- SHA1_Init() initializes a B<SHA_CTX> structure.
- SHA1_Update() can be called repeatedly with chunks of the message to
- be hashed (B<len> bytes at B<data>).
- SHA1_Final() places the message digest in B<md>, which must have space
- for SHA_DIGEST_LENGTH == 20 bytes of output, and erases the B<SHA_CTX>.
- Applications should use the higher level functions
- L<EVP_DigestInit(3)|EVP_DigestInit(3)>
- etc. instead of calling the hash functions directly.
- The predecessor of SHA-1, SHA, is also implemented, but it should be
- used only when backward compatibility is required.
- =head1 RETURN VALUES
- SHA1() returns a pointer to the hash value.
- SHA1_Init(), SHA1_Update() and SHA1_Final() return 1 for success, 0 otherwise.
- =head1 CONFORMING TO
- SHA: US Federal Information Processing Standard FIPS PUB 180 (Secure Hash
- Standard),
- SHA-1: US Federal Information Processing Standard FIPS PUB 180-1 (Secure Hash
- Standard),
- ANSI X9.30
- =head1 SEE ALSO
- L<ripemd(3)|ripemd(3)>, L<hmac(3)|hmac(3)>, L<EVP_DigestInit(3)|EVP_DigestInit(3)>
- =head1 HISTORY
- SHA1(), SHA1_Init(), SHA1_Update() and SHA1_Final() are available in all
- versions of SSLeay and OpenSSL.
- =cut
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