libressl-SHA1 - Secure Hash Algorithm

---

SHA1(3) Library Functions Manual SHA1(3)

NAME

SHA1, SHA1_Init, SHA1_Update, SHA1_Final, SHA224, SHA224_Init, SHA224_Update, SHA224_Final, SHA256, SHA256_Init, SHA256_Update, SHA256_Final, SHA384, SHA384_Init, SHA384_Update, SHA384_Final, SHA512, SHA512_Init, SHA512_Update, SHA512_Final — Secure Hash Algorithm

SYNOPSIS

library “libcrypto” #include <openssl/sha.h>

unsigned char *

SHA1(const unsigned char *d, size_t n, unsigned char *md);

int

SHA1_Init(SHA_CTX *c);

int

SHA1_Update(SHA_CTX *c, const void *data, size_t len);

int

SHA1_Final(unsigned char *md, SHA_CTX *c);

unsigned char *

SHA224(const unsigned char *d, size_t n, unsigned char *md);

int

SHA224_Init(SHA256_CTX *c);

int

SHA224_Update(SHA256_CTX *c, const void *data, size_t len);

int

SHA224_Final(unsigned char *md, SHA256_CTX *c);

unsigned char *

SHA256(const unsigned char *d, size_t n, unsigned char *md);

int

SHA256_Init(SHA256_CTX *c);

int

SHA256_Update(SHA256_CTX *c, const void *data, size_t len);

int

SHA256_Final(unsigned char *md, SHA256_CTX *c);

unsigned char *

SHA384(const unsigned char *d, size_t n, unsigned char *md);

int

SHA384_Init(SHA512_CTX *c);

int

SHA384_Update(SHA512_CTX *c, const void *data, size_t len);

int

SHA384_Final(unsigned char *md, SHA512_CTX *c);

unsigned char *

SHA512(const unsigned char *d, size_t n, unsigned char *md);

int

SHA512_Init(SHA512_CTX *c);

int

SHA512_Update(SHA512_CTX *c, const void *data, size_t len);

int

SHA512_Final(unsigned char *md, SHA512_CTX *c);

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 n bytes at d and places it in md, which must have space for SHA_DIGEST_LENGTH == 20 bytes of output.

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.

The SHA224, SHA256, SHA384, and SHA512 families of functions operate in the same way as the SHA1 functions. Note that SHA224 and SHA256 use a SHA256_CTX object instead of SHA_CTX, and SHA384 and SHA512 use SHA512_CTX. The buffer md must have space for the output from the SHA variant being used: SHA224_DIGEST_LENGTH, SHA256_DIGEST_LENGTH, SHA384_DIGEST_LENGTH, or SHA512_DIGEST_LENGTH bytes.

Applications should use the higher level functions EVP_DigestInit(3) etc. instead of calling the hash functions directly.

RETURN VALUES

SHA1(), SHA224(), SHA256(), SHA384(), and SHA512() return a pointer to the hash value. The other functions return 1 for success or 0 otherwise.

SEE ALSO

EVP_DigestInit(3), HMAC(3), RIPEMD160(3)

STANDARDS
Secure Hash Standard (SHS)

,

NIST FIPS Publication ,
180-4 ,
https://doi.org/10.6028/NIST.FIPS.180-4 ,
2015 .

HISTORY

SHA1(), SHA1_Init(), SHA1_Update(), and SHA1_Final() first appeared in SSLeay 0.5.1 and have been available since OpenBSD 2.4.

The other functions first appeared in OpenSSL 0.9.8 and have been available since OpenBSD 4.5.

CAVEATS

Other implementations allow md in SHA1(), SHA224(), SHA256(), SHA384(), and SHA512() to be NULL and return a static array, which is not thread safe. GNU June 8, 2025 SHA1(3)

---