---
name: "libressl-EVP_sha1"
section: "3"
platform: "linux"
package: "libressl"
version: "4.4.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libressl-EVP_sha1"
---

# libressl-EVP\_sha1(3)

legacy message digest algorithms

## NAME

**EVP\_sha1**, **EVP\_md5**, **EVP\_md5\_sha1**, **EVP\_md4** – legacy message digest algorithms

## SYNOPSIS

Crypto Library (libcrypto, -lcrypto)

**#include \<openssl/evp.h\>**

*const* *EVP\_MD* *\**\

**EVP\_sha1**(*void*);

*const* *EVP\_MD* *\**\

**EVP\_md5**(*void*);

*const* *EVP\_MD* *\**\

**EVP\_md5\_sha1**(*void*);

*const* *EVP\_MD* *\**\

**EVP\_md4**(*void*);

## DESCRIPTION

The following message digest algorithms are cryptographically broken. None of them should be used in new code unless there is no way around it.

**EVP\_sha1**() implements the SHA-1 algorithm and produces 160 bits of output from a given input. Examples of protocols and software still requiring it include OCSP, DNS, and the **git** version control system.

**EVP\_md5**() implements the MD5 algorithm and produces 128 bits of output from a given input. It is still occasionally used when no security is required but a fast hash algorithm is beneficial.

**EVP\_md5\_sha1**() produces concatenated MD5 and SHA-1 message digests. Do not use this except where it is required for the historic SSLv3 protocol.

**EVP\_md4**() implements the MD4 algorithm and produces 128 bits of output from a given input. It has been marked as “historic” by the Internet Engineering Task Force since 2011.

## RETURN VALUES

These functions return pointers to static *EVP\_MD* objects implementing the hash functions.

## SEE ALSO

evp(3), EVP\_DigestInit(3)

## STANDARDS

T. Polk, L. Chen, S. Turner, and P. Hoffman, *Security Considerations for the SHA-0 and SHA-1 Message-Digest Algorithms*, RFC 6194, March 2011.

S. Turner and L. Chen, *Updated Security Considerations for the MD5 Message-Digest and the HMAC-MD5 Algorithms*, RFC 6151, March 2011.

S. Turner and L. Chen, *MD4 to Historic Status*, RFC 6150, March 2011.

P. Kocher, P. Karlton, and A. Freier, *The Secure Sockets Layer (SSL) Protocol Version 3.0*, RFC 6101, August 2011.

## HISTORY

**EVP\_sha1**() and **EVP\_md5**() first appeared in SSLeay 0.5.1 and have been available since OpenBSD 2.4.

**EVP\_md4**() first appeared in OpenSSL 0.9.6 and has been available since OpenBSD 2.9.

**EVP\_md5\_sha1**() first appeared in OpenSSL 1.1.0 and has been available since OpenBSD 6.3.