/usr/man/cat.3/md5.3.Z(/usr/man/cat.3/md5.3.Z)

     md5(3)                 0.9.6h (2000-08-14)                 md5(3)

     NAME
          MD2, MD4, MD5, MD2_Init, MD2_Update, MD2_Final, MD4_Init,
          MD4_Update, MD4_Final, MD5_Init, MD5_Update, MD5_Final -
          MD2, MD4, and MD5 hash functions

     SYNOPSIS
           #include <openssl/md2.h>

           unsigned char *MD2(const unsigned char *d, unsigned long n,
                            unsigned char *md);

           void MD2_Init(MD2_CTX *c);
           void MD2_Update(MD2_CTX *c, const unsigned char *data,
                            unsigned long len);
           void MD2_Final(unsigned char *md, MD2_CTX *c);

           #include <openssl/md4.h>

           unsigned char *MD4(const unsigned char *d, unsigned long n,
                            unsigned char *md);

           void MD4_Init(MD4_CTX *c);
           void MD4_Update(MD4_CTX *c, const void *data,
                            unsigned long len);
           void MD4_Final(unsigned char *md, MD4_CTX *c);

           #include <openssl/md5.h>

           unsigned char *MD5(const unsigned char *d, unsigned long n,
                            unsigned char *md);

           void MD5_Init(MD5_CTX *c);
           void MD5_Update(MD5_CTX *c, const void *data,
                            unsigned long len);
           void MD5_Final(unsigned char *md, MD5_CTX *c);

     DESCRIPTION
          MD2, MD4, and MD5 are cryptographic hash functions with a
          128 bit output.

          MD2(), MD4(), and MD5() compute the MD2, MD4, and MD5
          message digest of the n bytes at d and place it in md (which
          must have space for MD2_DIGEST_LENGTH == MD4_DIGEST_LENGTH
          == MD5_DIGEST_LENGTH == 16 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:

          MD2_Init() initializes a MD2_CTX structure.

          MD2_Update() can be called repeatedly with chunks of the

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     md5(3)                 0.9.6h (2000-08-14)                 md5(3)

          message to be hashed (len bytes at data).

          MD2_Final() places the message digest in md, which must have
          space for MD2_DIGEST_LENGTH == 16 bytes of output, and
          erases the MD2_CTX.

          MD4_Init(), MD4_Update(), MD4_Final(), MD5_Init(),
          MD5_Update(), and MD5_Final() are analogous using an MD4_CTX
          and MD5_CTX structure.

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

     NOTE
          MD2, MD4, and MD5 are recommended only for compatibility
          with existing applications. In new applications, SHA-1 or
          RIPEMD-160 should be preferred.

     RETURN VALUES
          MD2(), MD4(), and MD5() return pointers to the hash value.

          MD2_Init(), MD2_Update(), MD2_Final(), MD4_Init(),
          MD4_Update(), MD4_Final(), MD5_Init(), MD5_Update(), and
          MD5_Final() do not return values.

     CONFORMING TO
          RFC 1319, RFC 1320, RFC 1321

     SEE ALSO
          sha(3), ripemd(3), EVP_DigestInit(3)

     HISTORY
          MD2(), MD2_Init(), MD2_Update() MD2_Final(), MD5(),
          MD5_Init(), MD5_Update() and MD5_Final() are available in
          all versions of SSLeay and OpenSSL.

          MD4(), MD4_Init(), and MD4_Update() are available in OpenSSL
          0.9.6 and above.

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