SYNOPSIS
#include
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);
DESCRIPTION
SHA-1 (Secure Hash Algorithm) is a cryptographic hash function with a 160bit output.
SHA1()computes the SHA-1 message digest of the nbytes at d and places it in md (which must have space for SHA_DIGEST_LENGTH == 20 bytes of output). If md is NULL, the digest is placed in a static array.
The following functions may be used if the message is not completely storedin memory:
SHA1_Init()initializes a SHA_CTX structure.
SHA1_Update()can be called repeatedly with chunks of themessage to be hashed (len bytes at data).
SHA1_Final()places the message digest in md, which must have space for SHA_DIGEST_LENGTH == 20 bytes of output, anderases the SHA_CTX.
Applications should use the higher level functionsEVP_DigestInit(3)etc. instead of calling the hash functions directly.
The predecessor of SHA-1, SHA, is also implemented, but it should be usedonly when backward compatibility is required.