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23 .TH CURLOPT_PINNEDPUBLICKEY 3 "January 25, 2018" "libcurl 7.59.0" "curl_easy_setopt options"
26 CURLOPT_PINNEDPUBLICKEY \- set pinned public key
28 #include <curl/curl.h>
30 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_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 server 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_PINNEDPUBLICKEY, "/etc/publickey.der");
57 curl_easy_setopt(curl, CURLOPT_PINNEDPUBLICKEY, "sha256//YhKJKSzoTt2b5FP18fvpHo7fJYqQCjAa3HWY3tvRMwE=;sha256//t62CeU2tQiqkexU74Gxa2eg7fRbEgoChTociMee9wno=");
60 /* Perform the request */
61 curl_easy_perform(curl);
64 .SH PUBLIC KEY EXTRACTION
65 If you do not have the server's public key file you can extract it from the
68 # retrieve the server's certificate if you don't already have it
70 # be sure to examine the certificate to see if it is what you expected
73 # - Use NUL instead of /dev/null.
74 # - OpenSSL may wait for input instead of disconnecting. Hit enter.
75 # - If you don't have sed, then just copy the certificate into a file:
76 # Lines from -----BEGIN CERTIFICATE----- to -----END CERTIFICATE-----.
78 openssl s_client -servername www.example.com -connect www.example.com:443 < /dev/null | sed -n "/-----BEGIN/,/-----END/p" > www.example.com.pem
80 # extract public key in pem format from certificate
81 openssl x509 -in www.example.com.pem -pubkey -noout > www.example.com.pubkey.pem
83 # convert public key from pem to der
84 openssl asn1parse -noout -inform pem -in www.example.com.pubkey.pem -out www.example.com.pubkey.der
86 # sha256 hash and base64 encode der to string for use
87 openssl dgst -sha256 -binary www.example.com.pubkey.der | openssl base64
89 The public key in PEM format contains a header, base64 data and a
92 -----BEGIN PUBLIC KEY-----
94 -----END PUBLIC KEY-----
99 7.39.0: OpenSSL, GnuTLS
101 7.39.0-7.48.0,7.58.1+: GSKit
103 7.43.0: NSS and wolfSSL/CyaSSL
109 7.54.1: SecureTransport/DarwinSSL on macOS 10.7+/iOS 10+
111 7.58.1: SChannel/WinSSL
115 7.44.0: OpenSSL, GnuTLS, NSS and wolfSSL/CyaSSL
121 7.54.1: SecureTransport/DarwinSSL on macOS 10.7+/iOS 10+
123 7.58.1: SChannel/WinSSL Windows XP SP3+
125 Other SSL backends not supported.
127 Returns CURLE_OK if TLS enabled, CURLE_UNKNOWN_OPTION if not, or
128 CURLE_OUT_OF_MEMORY if there was insufficient heap space.
130 .BR CURLOPT_SSL_VERIFYPEER "(3), "
131 .BR CURLOPT_SSL_VERIFYHOST "(3), "
132 .BR CURLOPT_CAINFO "(3), "
133 .BR CURLOPT_CAPATH "(3), "