Get a list of all supported digest algorithms

user_338476 0
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I was wondering how to obtain a list of EVP_MD* for all the supported digest algorithms dynamically. At the moment I'm using a static array

const EVP_MD* aHashAlgos[] = { EVP_sha512(), EVP_sha384(), EVP_sha256() ... }

Thank you!

openssl hash
1 Answers

The following will list all registered digest methods.

#include <openssl/evp.h>
#include <openssl/objects.h>
#include <stdio.h>

void my_callback(const OBJ_NAME *obj, void *arg)
{
  printf("Digest: %s\n", obj->name);
}

int main(int argc, char *argv)
{
  void *my_arg;
  OpenSSL_add_all_digests(); //make sure they're loaded

  my_arg = NULL;
  OBJ_NAME_do_all(OBJ_NAME_TYPE_MD_METH, my_callback, my_arg);
}

The callback receives objects of OBJ_NAME type:

typedef struct obj_name_st {
    int type;
    int alias;
    const char *name;
    const char *data;
} OBJ_NAME;

You can look up the associated EVP_MD* via EVP_get_digestbyname(). This method finds a lot of things, many of which you probably don't want:

$ ./a.out
Digest: ripemd160WithRSA
Digest: ssl2-md5
Digest: sha384
Digest: sha224
Digest: SHA224
Digest: md4
Digest: sha512
Digest: RSA-SHA256
Digest: DSA-SHA
Digest: sha1WithRSAEncryption
Digest: MD5
Digest: MD4
Digest: ssl3-sha1
Digest: ripemd160
Digest: sha
Digest: SHA384
Digest: SHA1
Digest: ssl3-md5
Digest: sha256
Digest: sha384WithRSAEncryption
Digest: SHA512
Digest: DSA-SHA1-old
Digest: dsaWithSHA1
Digest: ecdsa-with-SHA1
Digest: whirlpool
Digest: RSA-RIPEMD160
Digest: rmd160
Digest: RIPEMD160
Digest: RSA-SHA1-2
Digest: RSA-SHA1
Digest: dsaWithSHA
Digest: md5WithRSAEncryption
Digest: DSS1
Digest: RSA-MD5
Digest: dsaEncryption
Digest: ripemd
Digest: md4WithRSAEncryption
Digest: DSA
Digest: sha512WithRSAEncryption
Digest: SHA
Digest: dss1
Digest: RSA-SHA224
Digest: RSA-SHA512
Digest: SHA256
Digest: md5
Digest: RSA-SHA384
Digest: sha1
Digest: sha224WithRSAEncryption
Digest: RSA-SHA
Digest: shaWithRSAEncryption
Digest: sha256WithRSAEncryption
Digest: DSA-SHA1
Digest: RSA-MD4
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