curlopt_pinnedpublickey(3) [mojave man page]
CURLOPT_PINNEDPUBLICKEY(3) curl_easy_setopt options CURLOPT_PINNEDPUBLICKEY(3) NAME
CURLOPT_PINNEDPUBLICKEY - set pinned public key SYNOPSIS
#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PINNEDPUBLICKEY, char *pinnedpubkey); DESCRIPTION
Pass a pointer to a zero terminated string as parameter. The string can be the file name of your pinned public key. The file format expected is "PEM" or "DER". The string can also be any number of base64 encoded sha256 hashes preceded by "sha256//" and separated by ";" When negotiating a TLS or SSL connection, the server sends a certificate indicating its identity. A public key is extracted from this cer- tificate and if it does not exactly match the public key provided to this option, curl will abort the connection before sending or receiv- ing any data. On mismatch, CURLE_SSL_PINNEDPUBKEYNOTMATCH is returned. The application does not have to keep the string around after setting this option. DEFAULT
NULL PROTOCOLS
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. EXAMPLE
CURL *curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); curl_easy_setopt(curl, CURLOPT_PINNEDPUBLICKEY, "/etc/publickey.der"); /* OR curl_easy_setopt(curl, CURLOPT_PINNEDPUBLICKEY, "sha256//YhKJKSzoTt2b5FP18fvpHo7fJYqQCjAa3HWY3tvRMwE=;sha256//t62CeU2tQiqkexU74Gxa2eg7fRbEgoChTociMee9wno="); */ /* Perform the request */ curl_easy_perform(curl); } PUBLIC KEY EXTRACTION
If you do not have the server's public key file you can extract it from the server's certificate. # retrieve the server's certificate if you don't already have it # # be sure to examine the certificate to see if it is what you expected # # Windows-specific: # - Use NUL instead of /dev/null. # - OpenSSL may wait for input instead of disconnecting. Hit enter. # - If you don't have sed, then just copy the certificate into a file: # Lines from -----BEGIN CERTIFICATE----- to -----END CERTIFICATE-----. # openssl s_client -servername www.example.com -connect www.example.com:443 < /dev/null | sed -n "/-----BEGIN/,/-----END/p" > www.example.com.pem # extract public key in pem format from certificate openssl x509 -in www.example.com.pem -pubkey -noout > www.example.com.pubkey.pem # convert public key from pem to der openssl asn1parse -noout -inform pem -in www.example.com.pubkey.pem -out www.example.com.pubkey.der # sha256 hash and base64 encode der to string for use openssl dgst -sha256 -binary www.example.com.pubkey.der | openssl base64 The public key in PEM format contains a header, base64 data and a footer: -----BEGIN PUBLIC KEY----- [BASE 64 DATA] -----END PUBLIC KEY----- AVAILABILITY
PEM/DER support: 7.39.0: OpenSSL, GnuTLS and GSKit 7.43.0: NSS and wolfSSL/CyaSSL 7.47.0: mbedtls 7.49.0: PolarSSL sha256 support: 7.44.0: OpenSSL, GnuTLS, NSS and wolfSSL/CyaSSL 7.47.0: mbedtls 7.49.0: PolarSSL Other SSL backends not supported. RETURN VALUE
Returns CURLE_OK if TLS enabled, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space. SEE ALSO
CURLOPT_SSL_VERIFYPEER(3), CURLOPT_SSL_VERIFYHOST(3), CURLOPT_CAINFO(3), CURLOPT_CAPATH(3), libcurl 7.54.0 December 21, 2016 CURLOPT_PINNEDPUBLICKEY(3)
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CURLOPT_SSL_CTX_FUNCTION(3) curl_easy_setopt options CURLOPT_SSL_CTX_FUNCTION(3) NAME
CURLOPT_SSL_CTX_FUNCTION - SSL context callback for OpenSSL, wolfSSL/CyaSSL or mbedTLS SYNOPSIS
#include <curl/curl.h> CURLcode ssl_ctx_callback(CURL *curl, void *ssl_ctx, void *userptr); CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_CTX_FUNCTION, ssl_ctx_callback); DESCRIPTION
This option only works for libcurl powered by OpenSSL, wolfSSL/CyaSSL or mbedTLS. If libcurl was built against another SSL library this functionality is absent. Pass a pointer to your callback function, which should match the prototype shown above. This callback function gets called by libcurl just before the initialization of an SSL connection after having processed all other SSL related options to give a last chance to an application to modify the behaviour of the SSL initialization. The ssl_ctx parameter is actu- ally a pointer to the SSL library's SSL_CTX for OpenSSL or wolfSSL/CyaSSL, and a pointer to mbedtls_ssl_config for mbedTLS. If an error is returned from the callback no attempt to establish a connection is made and the perform operation will return the callback's error code. Set the userptr argument with the CURLOPT_SSL_CTX_DATA(3) option. This function will get called on all new connections made to a server, during the SSL negotiation. The ssl_ctx will point to a newly ini- tialized object each time, but note the pointer may be the same as from a prior call. To use this properly, a non-trivial amount of knowledge of your SSL library is necessary. For example, you can use this function to call library-specific callbacks to add additional validation code for certificates, and even to change the actual URI of a HTTPS request. DEFAULT
NULL PROTOCOLS
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. EXAMPLE
/* OpenSSL specific */ #include <openssl/ssl.h> #include <curl/curl.h> #include <stdio.h> static CURLcode sslctx_function(CURL *curl, void *sslctx, void *parm) { X509_STORE *store; X509 *cert=NULL; BIO *bio; char *mypem = /* example CA cert PEM - shortened */ "-----BEGIN CERTIFICATE----- " "MIIHPTCCBSWgAwIBAgIBADANBgkqhkiG9w0BAQQFADB5MRAwDgYDVQQKEwdSb290 " "IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNB " "IENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRA " "Y2FjZXJ0Lm9yZzAeFw0wMzAzMzAxMjI5NDlaFw0zMzAzMjkxMjI5NDlaMHkxEDAO " "GCSNe9FINSkYQKyTYOGWhlC0elnYjyELn8+CkcY7v2vcB5G5l1YjqrZslMZIBjzk " "zk6q5PYvCdxTby78dOs6Y5nCpqyJvKeyRKANihDjbPIky/qbn3BHLt4Ui9SyIAmW " "omTxJBzcoTWcFbLUvFUufQb1nA5V9FrWk9p2rSVzTMVD " "-----END CERTIFICATE----- "; /* get a BIO */ bio=BIO_new_mem_buf(mypem, -1); /* use it to read the PEM formatted certificate from memory into an * X509 structure that SSL can use */ PEM_read_bio_X509(bio, &cert, 0, NULL); if(cert == NULL) printf("PEM_read_bio_X509 failed... "); /* get a pointer to the X509 certificate store (which may be empty) */ store=SSL_CTX_get_cert_store((SSL_CTX *)sslctx); /* add our certificate to this store */ if(X509_STORE_add_cert(store, cert)==0) printf("error adding certificate "); /* decrease reference counts */ X509_free(cert); BIO_free(bio); /* all set to go */ return CURLE_OK; } int main(void) { CURL * ch; CURLcode rv; rv=curl_global_init(CURL_GLOBAL_ALL); ch=curl_easy_init(); rv=curl_easy_setopt(ch, CURLOPT_SSLCERTTYPE, "PEM"); rv=curl_easy_setopt(ch, CURLOPT_SSL_VERIFYPEER, 1L); rv=curl_easy_setopt(ch, CURLOPT_URL, "https://www.example.com/"); /* Retrieve page using cacerts' certificate -> will succeed * load the certificate by installing a function doing the necessary * "modifications" to the SSL CONTEXT just before link init */ rv=curl_easy_setopt(ch, CURLOPT_SSL_CTX_FUNCTION, *sslctx_function); rv=curl_easy_perform(ch); if(rv==CURLE_OK) printf("*** transfer succeeded *** "); else printf("*** transfer failed *** "); curl_easy_cleanup(ch); curl_global_cleanup(); return rv; } AVAILABILITY
Added in 7.11.0 for OpenSSL. Added in 7.42.0 for wolfSSL/CyaSSL. Added in 7.54.0 for mbedTLS. Other SSL backends not supported. RETURN VALUE
CURLE_OK if supported; or an error such as: CURLE_NOT_BUILT_IN - Not supported by the SSL backend CURLE_UNKNOWN_OPTION SEE ALSO
CURLOPT_SSL_CTX_DATA(3), CURLOPT_SSL_VERIFYPEER(3), libcurl 7.54.0 March 26, 2017 CURLOPT_SSL_CTX_FUNCTION(3)