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23 .TH CURLOPT_PROXY_PINNEDPUBLICKEY 3 "May 31, 2017" "libcurl 7.56.1" "curl_easy_setopt options"
26 CURLOPT_PROXY_PINNEDPUBLICKEY \- set pinned public key for https proxy
28 #include <curl/curl.h>
30 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_PINNEDPUBLICKEY, char *pinnedpubkey);
32 Pass a pointer to a zero terminated string as parameter. The string can be the
33 file name of your pinned public key. The file format expected is "PEM" or "DER".
34 The string can also be any number of base64 encoded sha256 hashes preceded by
35 "sha256//" and separated by ";"
37 When negotiating a TLS or SSL connection, the https proxy sends a certificate
38 indicating its identity. A public key is extracted from this certificate and
39 if it does not exactly match the public key provided to this option, curl will
40 abort the connection before sending or receiving any data.
42 On mismatch, \fICURLE_SSL_PINNEDPUBKEYNOTMATCH\fP is returned.
44 The application does not have to keep the string around after setting this
49 All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
52 CURL *curl = curl_easy_init();
54 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
55 curl_easy_setopt(curl, CURLOPT_PROXY, "https://proxy:443");
56 curl_easy_setopt(curl, CURLOPT_PROXY_PINNEDPUBLICKEY,
57 "sha256//YhKJKSzoTt2b5FP18fvpHo7fJYqQCjAa3HWY3tvRMwE=;sha256//t62CeU2tQiqkexU74Gxa2eg7fRbEgoChTociMee9wno=");
59 /* Perform the request */
60 curl_easy_perform(curl);
63 .SH PUBLIC KEY EXTRACTION
64 If you do not have the https proxy server's public key file you can extract it
65 from the https proxy server's certificate.
67 # retrieve the server's certificate if you don't already have it
69 # be sure to examine the certificate to see if it is what you expected
72 # - Use NUL instead of /dev/null.
73 # - OpenSSL may wait for input instead of disconnecting. Hit enter.
74 # - If you don't have sed, then just copy the certificate into a file:
75 # Lines from -----BEGIN CERTIFICATE----- to -----END CERTIFICATE-----.
77 openssl s_client -servername www.example.com -connect www.example.com:443 < /dev/null | sed -n "/-----BEGIN/,/-----END/p" > www.example.com.pem
79 # extract public key in pem format from certificate
80 openssl x509 -in www.example.com.pem -pubkey -noout > www.example.com.pubkey.pem
82 # convert public key from pem to der
83 openssl asn1parse -noout -inform pem -in www.example.com.pubkey.pem -out www.example.com.pubkey.der
85 # sha256 hash and base64 encode der to string for use
86 openssl dgst -sha256 -binary www.example.com.pubkey.der | openssl base64
88 The public key in PEM format contains a header, base64 data and a
91 -----BEGIN PUBLIC KEY-----
93 -----END PUBLIC KEY-----
98 7.52.0: GSKit, GnuTLS, NSS, OpenSSL, PolarSSL, mbedtls, wolfSSL/CyaSSL
102 7.52.0: GnuTLS, NSS, OpenSSL, PolarSSL, mbedtls, wolfSSL/CyaSSL
104 Other SSL backends not supported.
106 Returns CURLE_OK if TLS enabled, CURLE_UNKNOWN_OPTION if not, or
107 CURLE_OUT_OF_MEMORY if there was insufficient heap space.
109 .BR CURLOPT_PROXY_SSL_VERIFYPEER "(3), "
110 .BR CURLOPT_PROXY_SSL_VERIFYHOST "(3), "
111 .BR CURLOPT_PROXY_CAINFO "(3), "
112 .BR CURLOPT_PROXY_CAPATH "(3), "