Ugh. So simple! I don't know how I missed that. I found get0 & get1 accessors for many other structures but I didn't see that one.
Thanks,
Tom.III
On Tue, May 5, 2020 at 9:50 PM Dr Paul Dale <paul.dale@xxxxxxxxxx> wrote:
Might I suggest reading the documentation?RSA_get0_n() is the function you are wanting.Pauli--
Dr Paul Dale | Distinguished Architect | Cryptographic Foundations
Phone +61 7 3031 7217
Oracle Australia
On 6 May 2020, at 2:20 pm, Thomas Dwyer III <tomiii@xxxxxxxxxx> wrote:I'm porting some old legacy code from OpenSSL 1.0.2 to OpenSSL 3.0.0. A portion of this code reads X509 certificates, extracts the public key, and passes it to firmware that I cannot modify. Unfortunately, this legacy firmware API was very poorly designed such that the public key is passed in a way similar to:RSA *rsa = get_pubkey_from_cert(...)BIGNUM *bn = rsa->n;int len = BN_num_bytes(bn);unsigned char *buf = malloc(len);BN_bn2bin(bn, buf);pubkey_to_firmware(buf, len);Yuck. Ignoring the fact that this firmware appears to assume a constant exponent 'e', I cannot find a way to extract the modulus 'n' from the RSA key. I understand this is intentional. The only solution I could find is to print the key to a buffer via EVP_PKEY_print_public(), parse the result to extract the modulus into a giant hex string, and then BN_hex2bn() that back into a BIGNUM. Is there a better way?Thanks,Tom.III
