SHA1, SHA1_Init, SHA1_Update, SHA1_Final – Secure Hash Algorithm
unsigned char *SHA1(const unsigned char *d, unsigned long n,
unsigned char *md);
void SHA1_Init(SHA_CTX *c);
void SHA1_Update(SHA_CTX *c, const void *data,
unsigned long len);
void SHA1_Final(unsigned char *md, SHA_CTX *c);
SHA-1 (Secure Hash Algorithm) is a cryptographic hash function with a
160 bit output.
SHA1() computes the SHA-1 message digest of the n bytes 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
stored in memory:
SHA1_Init() initializes a SHA_CTX structure.
SHA1_Update() can be called repeatedly with chunks of the message 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, and erases the SHA_CTX.
Applications should use the higher level functions 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.
SHA1() returns a pointer to the hash value.
SHA1_Init(), SHA1_Update() and SHA1_Final() do not return values.
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