How to use openssl lib pem_read to read public/private key from a string

Question

I use openssl in C++ , copy the PrivateKey and PublicKey file content to two const char*, but I see the demo of api is only get pem public/private key from a pem file,so how can I get a public/private key from a string?

score 11 · Accepted Answer · answered Aug 21 '13 at 06:56

Try this:

char* mKey="-----BEGIN RSA PRIVATE KEY-----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\n1WJAxZeCFHWL6+/84zoDWwzXN0xQFzO0ZspxxQNFqCI=\n-----END RSA PRIVATE KEY-----";


BIO* bo = BIO_new( BIO_s_mem() );
BIO_write( bo, mKey,strlen(mKey));

EVP_PKEY* pkey = 0;
PEM_read_bio_PrivateKey( bo, &pkey, 0, 0 );

BIO_free(bo);


RSA* rsa = EVP_PKEY_get1_RSA( pkey );

...and to avoid memory leaks, at some point, after the last line, there most be a call to `EVP_PKEY_free(pkey);` — Maestro, Apr 16 '18 at 15:48
worth also mentioning SSL_CTX_use_PrivateKey(SSL_CTX *ctx, EVP_PKEY *pkey); to set pkey into ctx — LordTitiKaka, Dec 20 '18 at 10:00

score 2 · Answer 2 · edited Dec 02 '22 at 12:39

Here is the code to get public key from string in C++ using the openssl library.

#include <openssl/bio.h>
#include <openssl/rsa.h>

const std::string RsaPublicKey = "-----BEGIN PUBLIC KEY---";
RSA* public_key_;
BIO* bo = BIO_new(BIO_s_mem());
BIO_write(bo, RsaPublicKey.c_str(), RsaPublicKey.length());
PEM_read_bio_RSA_PUBKEY(bo, &public_key_, nullptr, nullptr);
BIO_free(bo);
RSA_free(public_key_);

How to use openssl lib pem_read to read public/private key from a string

2 Answers2

Linked