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/* copyright (c) 2022 - 2023 grunfink / MIT license */
#ifndef _XS_OPENSSL_H
#define _XS_OPENSSL_H
xs_str *_xs_digest(const xs_val *input, int size, const char *digest, int as_hex);
#ifndef _XS_MD5_H
#define xs_md5_hex(input, size) _xs_digest(input, size, "md5", 1)
#endif /* XS_MD5_H */
#ifndef _XS_BASE64_H
xs_str *xs_base64_enc(const xs_val *data, int sz);
xs_val *xs_base64_dec(const xs_str *data, int *size);
#endif /* XS_BASE64_H */
#define xs_sha1_hex(input, size) _xs_digest(input, size, "sha1", 1)
#define xs_sha256_hex(input, size) _xs_digest(input, size, "sha256", 1)
#define xs_sha256_base64(input, size) _xs_digest(input, size, "sha256", 0)
xs_dict *xs_evp_genkey(int bits);
xs_str *xs_evp_sign(const char *secret, const char *mem, int size);
int xs_evp_verify(const char *pubkey, const char *mem, int size, const char *b64sig);
#ifdef XS_IMPLEMENTATION
#include "openssl/rsa.h"
#include "openssl/pem.h"
#include "openssl/evp.h"
#ifndef _XS_BASE64_H
xs_str *xs_base64_enc(const xs_val *data, int sz)
/* encodes data to base64 */
{
BIO *mem, *b64;
BUF_MEM *bptr;
b64 = BIO_new(BIO_f_base64());
mem = BIO_new(BIO_s_mem());
b64 = BIO_push(b64, mem);
BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
BIO_write(b64, data, sz);
BIO_flush(b64);
BIO_get_mem_ptr(b64, &bptr);
int n = bptr->length;
xs_str *s = xs_realloc(NULL, _xs_blk_size(n + 1));
memcpy(s, bptr->data, n);
s[n] = '\0';
BIO_free_all(b64);
return s;
}
xs_val *xs_base64_dec(const xs_str *data, int *size)
/* decodes data from base64 */
{
BIO *b64, *mem;
*size = strlen(data);
b64 = BIO_new(BIO_f_base64());
mem = BIO_new_mem_buf(data, *size);
b64 = BIO_push(b64, mem);
BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
/* alloc a very big buffer */
xs_str *s = xs_realloc(NULL, *size);
*size = BIO_read(b64, s, *size);
/* adjust to current size */
s = xs_realloc(s, _xs_blk_size(*size + 1));
s[*size] = '\0';
BIO_free_all(mem);
return s;
}
#endif /* _XS_BASE64_H */
xs_str *_xs_digest(const xs_val *input, int size, const char *digest, int as_hex)
/* generic function for generating and encoding digests */
{
const EVP_MD *md;
if ((md = EVP_get_digestbyname(digest)) == NULL)
return NULL;
unsigned char output[1024];
unsigned int out_size;
EVP_MD_CTX *mdctx;
mdctx = EVP_MD_CTX_new();
EVP_DigestInit_ex(mdctx, md, NULL);
EVP_DigestUpdate(mdctx, input, size);
EVP_DigestFinal_ex(mdctx, output, &out_size);
EVP_MD_CTX_free(mdctx);
return as_hex ? xs_hex_enc ((char *)output, out_size) :
xs_base64_enc((char *)output, out_size);
}
xs_dict *xs_evp_genkey(int bits)
/* generates an RSA keypair using the EVP interface */
{
xs_dict *keypair = NULL;
EVP_PKEY_CTX *ctx;
EVP_PKEY *pkey = NULL;
if ((ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL)) == NULL)
goto end;
if (EVP_PKEY_keygen_init(ctx) <= 0 ||
EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, bits) <= 0 ||
EVP_PKEY_keygen(ctx, &pkey) <= 0)
goto end;
BIO *bs = BIO_new(BIO_s_mem());
BIO *bp = BIO_new(BIO_s_mem());
BUF_MEM *sptr;
BUF_MEM *pptr;
PEM_write_bio_PrivateKey(bs, pkey, NULL, NULL, 0, 0, NULL);
BIO_get_mem_ptr(bs, &sptr);
PEM_write_bio_PUBKEY(bp, pkey);
BIO_get_mem_ptr(bp, &pptr);
keypair = xs_dict_new();
keypair = xs_dict_append(keypair, "secret", sptr->data);
keypair = xs_dict_append(keypair, "public", pptr->data);
BIO_free(bs);
BIO_free(bp);
end:
return keypair;
}
xs_str *xs_evp_sign(const char *secret, const char *mem, int size)
/* signs a memory block (secret is in PEM format) */
{
xs_str *signature = NULL;
BIO *b;
unsigned char *sig;
unsigned int sig_len;
EVP_PKEY *pkey;
EVP_MD_CTX *mdctx;
const EVP_MD *md;
/* un-PEM the key */
b = BIO_new_mem_buf(secret, strlen(secret));
pkey = PEM_read_bio_PrivateKey(b, NULL, NULL, NULL);
/* I've learnt all these magical incantations by watching
the Python module code and the OpenSSL manual pages */
/* Well, "learnt" may be an overstatement */
md = EVP_get_digestbyname("sha256");
mdctx = EVP_MD_CTX_new();
sig_len = EVP_PKEY_size(pkey);
sig = xs_realloc(NULL, sig_len);
EVP_SignInit(mdctx, md);
EVP_SignUpdate(mdctx, mem, size);
if (EVP_SignFinal(mdctx, sig, &sig_len, pkey) == 1)
signature = xs_base64_enc((char *)sig, sig_len);
EVP_MD_CTX_free(mdctx);
EVP_PKEY_free(pkey);
BIO_free(b);
xs_free(sig);
return signature;
}
int xs_evp_verify(const char *pubkey, const char *mem, int size, const char *b64sig)
/* verifies a base64 block, returns non-zero on ok */
{
int r = 0;
BIO *b;
EVP_PKEY *pkey;
EVP_MD_CTX *mdctx;
const EVP_MD *md;
/* un-PEM the key */
b = BIO_new_mem_buf(pubkey, strlen(pubkey));
pkey = PEM_read_bio_PUBKEY(b, NULL, NULL, NULL);
md = EVP_get_digestbyname("sha256");
mdctx = EVP_MD_CTX_new();
if (pkey != NULL) {
xs *sig = NULL;
int s_size;
/* de-base64 */
sig = xs_base64_dec(b64sig, &s_size);
if (sig != NULL) {
EVP_VerifyInit(mdctx, md);
EVP_VerifyUpdate(mdctx, mem, size);
r = EVP_VerifyFinal(mdctx, (unsigned char *)sig, s_size, pkey);
}
}
EVP_MD_CTX_free(mdctx);
EVP_PKEY_free(pkey);
BIO_free(b);
return r;
}
#endif /* XS_IMPLEMENTATION */
#endif /* _XS_OPENSSL_H */
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