curlopt_ssl_verifypeer(3) [mojave man page]
CURLOPT_SSL_VERIFYPEER(3) curl_easy_setopt options CURLOPT_SSL_VERIFYPEER(3) NAME
CURLOPT_SSL_VERIFYPEER - verify the peer's SSL certificate SYNOPSIS
#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_VERIFYPEER, long verify); DESCRIPTION
Pass a long as parameter to enable or disable. This option determines whether curl verifies the authenticity of the peer's certificate. A value of 1 means curl verifies; 0 (zero) means it doesn't. When negotiating a TLS or SSL connection, the server sends a certificate indicating its identity. Curl verifies whether the certificate is authentic, i.e. that you can trust that the server is who the certificate says it is. This trust is based on a chain of digital signa- tures, rooted in certification authority (CA) certificates you supply. curl uses a default bundle of CA certificates (the path for that is determined at build time) and you can specify alternate certificates with the CURLOPT_CAINFO(3) option or the CURLOPT_CAPATH(3) option. When CURLOPT_SSL_VERIFYPEER(3) is enabled, and the verification fails to prove that the certificate is authentic, the connection fails. When the option is zero, the peer certificate verification succeeds regardless. Authenticating the certificate is not enough to be sure about the server. You typically also want to ensure that the server is the server you mean to be talking to. Use CURLOPT_SSL_VERIFYHOST(3) for that. The check that the host name in the certificate is valid for the host name you're connecting to is done independently of the CURLOPT_SSL_VERIFYPEER(3) option. WARNING: disabling verification of the certificate allows bad guys to man-in-the-middle the communication without you knowing it. Disabling verification makes the communication insecure. Just having encryption on a transfer is not enough as you cannot be sure that you are commu- nicating with the correct end-point. DEFAULT
By default, curl assumes a value of 1. 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"); /* Set the default value: strict certificate check please */ curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L); curl_easy_perform(curl); } AVAILABILITY
If built TLS enabled. RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. SEE ALSO
CURLOPT_SSL_VERIFYHOST(3), CURLOPT_PROXY_SSL_VERIFYPEER(3), CURLOPT_PROXY_SSL_VERIFYHOST(3), libcurl 7.54.0 February 09, 2017 CURLOPT_SSL_VERIFYPEER(3)
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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)