309 lines
11 KiB
C
309 lines
11 KiB
C
/* srp.h
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*
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* Copyright (C) 2006-2017 wolfSSL Inc.
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*
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* This file is part of wolfSSL.
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*
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* wolfSSL is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* wolfSSL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
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*/
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#ifdef WOLFCRYPT_HAVE_SRP
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#ifndef WOLFCRYPT_SRP_H
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#define WOLFCRYPT_SRP_H
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#include <wolfssl/wolfcrypt/types.h>
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#include <wolfssl/wolfcrypt/sha.h>
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#include <wolfssl/wolfcrypt/sha256.h>
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#include <wolfssl/wolfcrypt/sha512.h>
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#include <wolfssl/wolfcrypt/integer.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Select the largest available hash for the buffer size. */
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#if defined(WOLFSSL_SHA512)
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#define SRP_MAX_DIGEST_SIZE WC_SHA512_DIGEST_SIZE
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#elif defined(WOLFSSL_SHA384)
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#define SRP_MAX_DIGEST_SIZE WC_SHA384_DIGEST_SIZE
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#elif !defined(NO_SHA256)
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#define SRP_MAX_DIGEST_SIZE WC_SHA256_DIGEST_SIZE
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#elif !defined(NO_SHA)
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#define SRP_MAX_DIGEST_SIZE WC_SHA_DIGEST_SIZE
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#else
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#error "You have to have some kind of SHA hash if you want to use SRP."
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#endif
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/* Set the minimum number of bits acceptable in an SRP modulus */
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#define SRP_MODULUS_MIN_BITS 512
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/* Set the minimum number of bits acceptable for private keys (RFC 5054) */
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#define SRP_PRIVATE_KEY_MIN_BITS 256
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/* salt size for SRP password */
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#define SRP_SALT_SIZE 16
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/**
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* SRP side, client or server.
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*/
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typedef enum {
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SRP_CLIENT_SIDE = 0,
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SRP_SERVER_SIDE = 1,
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} SrpSide;
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/**
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* SRP hash type, SHA[1|256|384|512].
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*/
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typedef enum {
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SRP_TYPE_SHA = 1,
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SRP_TYPE_SHA256 = 2,
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SRP_TYPE_SHA384 = 3,
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SRP_TYPE_SHA512 = 4,
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} SrpType;
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/**
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* SRP hash struct.
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*/
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typedef struct {
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byte type;
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union {
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#ifndef NO_SHA
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wc_Sha sha;
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#endif
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#ifndef NO_SHA256
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wc_Sha256 sha256;
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#endif
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#ifdef WOLFSSL_SHA384
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wc_Sha384 sha384;
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#endif
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#ifdef WOLFSSL_SHA512
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wc_Sha512 sha512;
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#endif
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} data;
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} SrpHash;
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typedef struct Srp {
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SrpSide side; /**< Client or Server, @see SrpSide. */
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SrpType type; /**< Hash type, @see SrpType. */
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byte* user; /**< Username, login. */
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word32 userSz; /**< Username length. */
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byte* salt; /**< Small salt. */
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word32 saltSz; /**< Salt length. */
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mp_int N; /**< Modulus. N = 2q+1, [q, N] are primes.*/
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mp_int g; /**< Generator. A generator modulo N. */
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byte k[SRP_MAX_DIGEST_SIZE]; /**< Multiplier parameter. k = H(N, g) */
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mp_int auth; /**< Client: x = H(salt + H(user:pswd)) */
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/**< Server: v = g ^ x % N */
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mp_int priv; /**< Private ephemeral value. */
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SrpHash client_proof; /**< Client proof. Sent to the Server. */
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SrpHash server_proof; /**< Server proof. Sent to the Client. */
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byte* key; /**< Session key. */
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word32 keySz; /**< Session key length. */
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int (*keyGenFunc_cb) (struct Srp* srp, byte* secret, word32 size);
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/**< Function responsible for generating the session key. */
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/**< It MUST use XMALLOC with type DYNAMIC_TYPE_SRP to allocate the */
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/**< key buffer for this structure and set keySz to the buffer size. */
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/**< The default function used by this implementation is a modified */
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/**< version of t_mgf1 that uses the proper hash function according */
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/**< to srp->type. */
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void* heap; /**< heap hint pointer */
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} Srp;
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/**
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* Initializes the Srp struct for usage.
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*
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* @param[out] srp the Srp structure to be initialized.
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* @param[in] type the hash type to be used.
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* @param[in] side the side of the communication.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpInit(Srp* srp, SrpType type, SrpSide side);
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/**
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* Releases the Srp struct resources after usage.
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*
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* @param[in,out] srp the Srp structure to be terminated.
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*/
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WOLFSSL_API void wc_SrpTerm(Srp* srp);
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/**
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* Sets the username.
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*
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* This function MUST be called after wc_SrpInit.
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*
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* @param[in,out] srp the Srp structure.
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* @param[in] username the buffer containing the username.
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* @param[in] size the username size in bytes
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpSetUsername(Srp* srp, const byte* username, word32 size);
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/**
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* Sets the srp parameters based on the username.
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*
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* This function MUST be called after wc_SrpSetUsername.
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*
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* @param[in,out] srp the Srp structure.
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* @param[in] N the Modulus. N = 2q+1, [q, N] are primes.
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* @param[in] nSz the N size in bytes.
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* @param[in] g the Generator modulo N.
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* @param[in] gSz the g size in bytes
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* @param[in] salt a small random salt. Specific for each username.
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* @param[in] saltSz the salt size in bytes
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpSetParams(Srp* srp, const byte* N, word32 nSz,
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const byte* g, word32 gSz,
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const byte* salt, word32 saltSz);
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/**
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* Sets the password.
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*
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* Setting the password does not persists the clear password data in the
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* srp structure. The client calculates x = H(salt + H(user:pswd)) and stores
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* it in the auth field.
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*
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* This function MUST be called after wc_SrpSetParams and is CLIENT SIDE ONLY.
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*
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* @param[in,out] srp the Srp structure.
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* @param[in] password the buffer containing the password.
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* @param[in] size the password size in bytes.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpSetPassword(Srp* srp, const byte* password, word32 size);
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/**
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* Sets the verifier.
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*
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* This function MUST be called after wc_SrpSetParams and is SERVER SIDE ONLY.
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*
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* @param[in,out] srp the Srp structure.
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* @param[in] verifier the buffer containing the verifier.
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* @param[in] size the verifier size in bytes.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpSetVerifier(Srp* srp, const byte* verifier, word32 size);
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/**
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* Gets the verifier.
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*
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* The client calculates the verifier with v = g ^ x % N.
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* This function MAY be called after wc_SrpSetPassword and is CLIENT SIDE ONLY.
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*
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* @param[in,out] srp the Srp structure.
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* @param[out] verifier the buffer to write the verifier.
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* @param[in,out] size the buffer size in bytes. Will be updated with the
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* verifier size.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpGetVerifier(Srp* srp, byte* verifier, word32* size);
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/**
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* Sets the private ephemeral value.
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*
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* The private ephemeral value is known as:
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* a at the client side. a = random()
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* b at the server side. b = random()
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* This function is handy for unit test cases or if the developer wants to use
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* an external random source to set the ephemeral value.
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* This function MAY be called before wc_SrpGetPublic.
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*
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* @param[in,out] srp the Srp structure.
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* @param[in] priv the ephemeral value.
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* @param[in] size the private size in bytes.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpSetPrivate(Srp* srp, const byte* priv, word32 size);
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/**
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* Gets the public ephemeral value.
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*
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* The public ephemeral value is known as:
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* A at the client side. A = g ^ a % N
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* B at the server side. B = (k * v + (g ˆ b % N)) % N
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* This function MUST be called after wc_SrpSetPassword or wc_SrpSetVerifier.
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*
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* @param[in,out] srp the Srp structure.
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* @param[out] pub the buffer to write the public ephemeral value.
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* @param[in,out] size the the buffer size in bytes. Will be updated with
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* the ephemeral value size.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpGetPublic(Srp* srp, byte* pub, word32* size);
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/**
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* Computes the session key.
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*
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* The key can be accessed at srp->key after success.
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*
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* @param[in,out] srp the Srp structure.
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* @param[in] clientPubKey the client's public ephemeral value.
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* @param[in] clientPubKeySz the client's public ephemeral value size.
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* @param[in] serverPubKey the server's public ephemeral value.
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* @param[in] serverPubKeySz the server's public ephemeral value size.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpComputeKey(Srp* srp,
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byte* clientPubKey, word32 clientPubKeySz,
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byte* serverPubKey, word32 serverPubKeySz);
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/**
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* Gets the proof.
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*
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* This function MUST be called after wc_SrpComputeKey.
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*
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* @param[in,out] srp the Srp structure.
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* @param[out] proof the buffer to write the proof.
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* @param[in,out] size the buffer size in bytes. Will be updated with the
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* proof size.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpGetProof(Srp* srp, byte* proof, word32* size);
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/**
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* Verifies the peers proof.
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*
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* This function MUST be called before wc_SrpGetSessionKey.
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*
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* @param[in,out] srp the Srp structure.
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* @param[in] proof the peers proof.
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* @param[in] size the proof size in bytes.
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*
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* @return 0 on success, {@literal <} 0 on error. @see error-crypt.h
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*/
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WOLFSSL_API int wc_SrpVerifyPeersProof(Srp* srp, byte* proof, word32 size);
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif /* WOLFCRYPT_SRP_H */
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#endif /* WOLFCRYPT_HAVE_SRP */
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