CODEWITHSUNDEEP
c++crsapublic-key-encryption
Martin Schlott
Martin Schlott

Reputation: 4557

How to load RSA key pair without Openssl or other Library

CCFor a project I was searching for a simple RSA implementation to exchange a small secret via an unsecured but existing communication protocol. To keep it small and easy to portable to different platforms I did not want to link against OpenSSL or Crypto++. I found that as a part of the axTLS project which has a suitable license and an easy to extract RSA algorithm. The rsa function for encryption needs two components (as it usses the public key). The pup_exp is 65537 and modulus is the public part of the key and priv_exp the private one.

void RSA_priv_key_new(RSA_CTX **ctx, 
        const uint8_t *modulus, int mod_len,
        const uint8_t *pub_exp, int pub_len,
        const uint8_t *priv_exp, int priv_len
    )

For easy use for the user, I want to load a certificate like X.509 or PEM generated by a library like OpenSSL, but in C or C++ code without including the whole OpenSSL stuff. But at the moment I even did not find an understandable documentation of the common key file formats.

Upvotes: 2

Views: 909

Answers (1)

kanak
kanak

Reputation: 593

There are two types of RSA public key format widely used and they are PKCS#1 and X.509(SubjectPublicKeyInfo). I have used libtomcrypt(http://libtom.org/?page=features). It supports both the RSA key formats and very much portable. The license is non restrictive.

Upvotes: 1

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