EVP_DecodeBlock
outlen = EVP_DecodeBlock(outbuf, (unsigned char *)in, inlen);
z = EVP_DecodeBlock((unsigned char *)ctx->buf,
decoded_len = EVP_DecodeBlock(out, d, n);
decoded_len = EVP_DecodeBlock(out, d, n);
i = EVP_DecodeBlock(out, ctx->enc_data, ctx->num);
spki_len = EVP_DecodeBlock(spki_der, (const unsigned char *)str, len);
int EVP_DecodeBlock(unsigned char *t, const unsigned char *f, int n);