Query: curlopt_pinnedpublickey
OS: mojave
Section: 3
Format: Original Unix Latex Style Formatted with HTML and a Horizontal Scroll Bar
CURLOPT_PINNEDPUBLICKEY(3) curl_easy_setopt options CURLOPT_PINNEDPUBLICKEY(3)NAMECURLOPT_PINNEDPUBLICKEY - set pinned public keySYNOPSIS#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PINNEDPUBLICKEY, char *pinnedpubkey);DESCRIPTIONPass 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.DEFAULTNULLPROTOCOLSAll TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.EXAMPLECURL *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 EXTRACTIONIf 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-----AVAILABILITYPEM/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 VALUEReturns CURLE_OK if TLS enabled, CURLE_UNKNOWN_OPTION if not, or CURLE_OUT_OF_MEMORY if there was insufficient heap space.SEE ALSOCURLOPT_SSL_VERIFYPEER(3), CURLOPT_SSL_VERIFYHOST(3), CURLOPT_CAINFO(3), CURLOPT_CAPATH(3), libcurl 7.54.0 December 21, 2016 CURLOPT_PINNEDPUBLICKEY(3)