mirror of
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0f84cbc3e2
Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org> (Merged from https://github.com/openssl/openssl/pull/12595)
218 lines
8.0 KiB
Plaintext
218 lines
8.0 KiB
Plaintext
=pod
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=head1 NAME
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SSL_CTX_set_srp_username,
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SSL_CTX_set_srp_password,
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SSL_CTX_set_srp_strength,
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SSL_CTX_set_srp_cb_arg,
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SSL_CTX_set_srp_username_callback,
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SSL_CTX_set_srp_client_pwd_callback,
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SSL_CTX_set_srp_verify_param_callback,
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SSL_set_srp_server_param,
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SSL_set_srp_server_param_pw,
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SSL_get_srp_g,
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SSL_get_srp_N,
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SSL_get_srp_username,
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SSL_get_srp_userinfo
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- SRP control operations
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=head1 SYNOPSIS
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#include <openssl/ssl.h>
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int SSL_CTX_set_srp_username(SSL_CTX *ctx, char *name);
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int SSL_CTX_set_srp_password(SSL_CTX *ctx, char *password);
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int SSL_CTX_set_srp_strength(SSL_CTX *ctx, int strength);
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int SSL_CTX_set_srp_cb_arg(SSL_CTX *ctx, void *arg);
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int SSL_CTX_set_srp_username_callback(SSL_CTX *ctx,
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int (*cb) (SSL *s, int *ad, void *arg));
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int SSL_CTX_set_srp_client_pwd_callback(SSL_CTX *ctx,
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char *(*cb) (SSL *s, void *arg));
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int SSL_CTX_set_srp_verify_param_callback(SSL_CTX *ctx,
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int (*cb) (SSL *s, void *arg));
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int SSL_set_srp_server_param(SSL *s, const BIGNUM *N, const BIGNUM *g,
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BIGNUM *sa, BIGNUM *v, char *info);
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int SSL_set_srp_server_param_pw(SSL *s, const char *user, const char *pass,
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const char *grp);
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BIGNUM *SSL_get_srp_g(SSL *s);
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BIGNUM *SSL_get_srp_N(SSL *s);
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char *SSL_get_srp_username(SSL *s);
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char *SSL_get_srp_userinfo(SSL *s);
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=head1 DESCRIPTION
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These functions provide access to SRP (Secure Remote Password) parameters,
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an alternate authentication mechanism for TLS. SRP allows the use of usernames
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and passwords over unencrypted channels without revealing the password to an
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eavesdropper. SRP also supplies a shared secret at the end of the authentication
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sequence that can be used to generate encryption keys.
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The SRP protocol, version 3 is specified in RFC 2945. SRP version 6 is described
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in RFC 5054 with applications to TLS authentication.
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The SSL_CTX_set_srp_username() function sets the SRP username for B<ctx>. This
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should be called on the client prior to creating a connection to the server.
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The length of B<name> must be shorter or equal to 255 characters.
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The SSL_CTX_set_srp_password() function sets the SRP password for B<ctx>. This
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may be called on the client prior to creating a connection to the server.
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This overrides the effect of SSL_CTX_set_srp_client_pwd_callback().
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The SSL_CTX_set_srp_strength() function sets the SRP strength for B<ctx>. This
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is the minimal length of the SRP prime in bits. If not specified 1024 is used.
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If not satisfied by the server key exchange the connection will be rejected.
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The SSL_CTX_set_srp_cb_arg() function sets an extra parameter that will
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be passed to all following callbacks as B<arg>.
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The SSL_CTX_set_srp_username_callback() function sets the server side callback
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that is invoked when an SRP username is found in a ClientHello.
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The callback parameters are the SSL connection B<s>, a writable error flag B<ad>
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and the extra argument B<arg> set by SSL_CTX_set_srp_cb_arg().
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This callback should setup the server for the key exchange by calling
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SSL_set_srp_server_param() with the appropriate parameters for the received
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username. The username can be obtained by calling SSL_get_srp_username().
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See L<SRP_VBASE_init(3)> to parse the verifier file created by L<openssl-srp(1)> or
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L<SRP_create_verifier(3)> to generate it.
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The callback should return B<SSL_ERROR_NONE> to proceed with the server key exchange,
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B<SSL3_AL_FATAL> for a fatal error or any value < 0 for a retryable error.
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In the event of a B<SSL3_AL_FATAL> the alert flag given by B<*al> will be sent
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back. By default this will be B<SSL_AD_UNKNOWN_PSK_IDENTITY>.
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The SSL_CTX_set_srp_client_pwd_callback() function sets the client password
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callback on the client.
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The callback parameters are the SSL connection B<s> and the extra argument B<arg>
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set by SSL_CTX_set_srp_cb_arg().
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The callback will be called as part of the generation of the client secrets.
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It should return the client password in text form or NULL to abort the connection.
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The resulting memory will be freed by the library as part of the callback resolution.
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This overrides the effect of SSL_CTX_set_srp_password().
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The SSL_CTX_set_srp_verify_param_callback() sets the SRP gN parameter verification
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callback on the client. This allows the client to perform custom verification when
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receiving the server SRP proposed parameters.
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The callback parameters are the SSL connection B<s> and the extra argument B<arg>
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set by SSL_CTX_set_srp_cb_arg().
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The callback should return a positive value to accept the server parameters.
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Returning 0 or a negative value will abort the connection. The server parameters
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can be obtained by calling SSL_get_srp_N() and SSL_get_srp_g().
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Sanity checks are already performed by the library after the handshake
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(B % N non zero, check against the strength parameter) and are not necessary.
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If no callback is set the g and N parameters will be checked against
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known RFC 5054 values.
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The SSL_set_srp_server_param() function sets all SRP parameters for
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the connection B<s>. B<N> and B<g> are the SRP group parameters, B<sa> is the
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user salt, B<v> the password verifier and B<info> is the optional user info.
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The SSL_set_srp_server_param_pw() function sets all SRP parameters for the
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connection B<s> by generating a random salt and a password verifier.
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B<user> is the username, B<pass> the password and B<grp> the SRP group parameters
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identifier for L<SRP_get_default_gN(3)>.
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The SSL_get_srp_g() function returns the SRP group generator for B<s>, or from
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the underlying SSL_CTX if it is NULL.
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The SSL_get_srp_N() function returns the SRP prime for B<s>, or from
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the underlying SSL_CTX if it is NULL.
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The SSL_get_srp_username() function returns the SRP username for B<s>, or from
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the underlying SSL_CTX if it is NULL.
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The SSL_get_srp_userinfo() function returns the SRP user info for B<s>, or from
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the underlying SSL_CTX if it is NULL.
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=head1 RETURN VALUES
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All SSL_CTX_set_* functions return 1 on success and 0 on failure.
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SSL_set_srp_server_param() returns 1 on success and -1 on failure.
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The SSL_get_SRP_* functions return a pointer to the requested data, the memory
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is owned by the library and should not be freed by the caller.
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=head1 EXAMPLES
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Setup SRP parameters on the client:
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#include <openssl/ssl.h>
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const char *username = "username";
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const char *password = "password";
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SSL_CTX *ctx = SSL_CTX_new(TLS_client_method());
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if (!ctx)
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/* Error */
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if (!SSL_CTX_set_srp_username(ctx, username))
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/* Error */
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if (!SSL_CTX_set_srp_password(ctx, password))
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/* Error */
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Setup SRP server with verifier file:
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#include <openssl/srp.h>
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#include <openssl/ssl.h>
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const char *srpvfile = "password.srpv";
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int srpServerCallback(SSL *s, int *ad, void *arg)
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{
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SRP_VBASE *srpData = (SRP_VBASE*) arg;
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char *username = SSL_get_srp_username(s);
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SRP_user_pwd *user_pwd = SRP_VBASE_get1_by_user(srpData, username);
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if (!user_pwd)
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/* Error */
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return SSL3_AL_FATAL;
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if (SSL_set_srp_server_param(s, user_pwd->N, user_pwd->g,
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user_pwd->s, user_pwd->v, user_pwd->info) < 0)
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/* Error */
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SRP_user_pwd_free(user_pwd);
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return SSL_ERROR_NONE;
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}
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SSL_CTX *ctx = SSL_CTX_new(TLS_server_method());
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if (!ctx)
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/* Error */
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/*
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* seedKey should contain a NUL terminated sequence
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* of random non NUL bytes
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*/
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const char *seedKey;
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SRP_VBASE *srpData = SRP_VBASE_new(seedKey);
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if (SRP_VBASE_init(srpData, (char*) srpvfile) != SRP_NO_ERROR)
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/* Error */
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SSL_CTX_set_srp_cb_arg(ctx, srpData);
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SSL_CTX_set_srp_username_callback(ctx, srpServerCallback);
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=head1 SEE ALSO
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L<ssl(7)>,
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L<openssl-srp(1)>,
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L<SRP_VBASE_new(3)>,
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L<SRP_create_verifier(3)>
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=head1 HISTORY
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These functions were added in OpenSSL 1.0.1.
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=head1 COPYRIGHT
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Copyright 2018-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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