RSA with OpenSSL
This commit is contained in:
Tobias Brunner
@@ -0,0 +1,433 @@
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/*
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* Copyright (C) 2008 Tobias Brunner
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* $Id$
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*/
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#include "openssl_rsa_public_key.h"
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#include <debug.h>
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#include <openssl/evp.h>
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#include <openssl/rsa.h>
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#include <openssl/x509.h>
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typedef struct private_openssl_rsa_public_key_t private_openssl_rsa_public_key_t;
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/**
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* Private data structure with signing context.
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*/
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struct private_openssl_rsa_public_key_t {
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/**
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* Public interface for this signer.
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*/
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openssl_rsa_public_key_t public;
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/**
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* RSA object from OpenSSL
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*/
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RSA *rsa;
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/**
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* Keyid formed as a SHA-1 hash of a publicKeyInfo object
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*/
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identification_t *keyid_info;
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/**
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* Keyid formed as a SHA-1 hash of a publicKey object
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*/
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identification_t *keyid;
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/**
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* reference counter
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*/
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refcount_t ref;
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};
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/**
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* Verification of an EMPSA PKCS1 signature described in PKCS#1
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*/
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static bool verify_emsa_pkcs1_signature(private_openssl_rsa_public_key_t *this,
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int type, chunk_t data, chunk_t signature)
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{
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bool valid = FALSE;
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const EVP_MD *hasher = EVP_get_digestbynid(type);
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if (!hasher)
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{
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return FALSE;
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}
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EVP_MD_CTX *ctx = EVP_MD_CTX_create();
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EVP_PKEY *key = EVP_PKEY_new();
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if (!ctx || !key)
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{
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goto error;
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}
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if (!EVP_PKEY_set1_RSA(key, this->rsa))
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{
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goto error;
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}
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if (!EVP_VerifyInit_ex(ctx, hasher, NULL))
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{
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goto error;
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}
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if (!EVP_VerifyUpdate(ctx, data.ptr, data.len))
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{
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goto error;
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}
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/* remove any preceding 0-bytes from signature */
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while (signature.len && *(signature.ptr) == 0x00)
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{
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signature.len -= 1;
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signature.ptr++;
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}
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valid = (EVP_VerifyFinal(ctx, signature.ptr, signature.len, key) == 1);
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error:
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if (key)
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{
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EVP_PKEY_free(key);
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}
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if (ctx)
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{
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EVP_MD_CTX_destroy(ctx);
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}
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return valid;
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}
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/**
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* Implementation of public_key_t.get_type.
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*/
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static key_type_t get_type(private_openssl_rsa_public_key_t *this)
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{
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return KEY_RSA;
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}
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/**
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* Implementation of public_key_t.verify.
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*/
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static bool verify(private_openssl_rsa_public_key_t *this, signature_scheme_t scheme,
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chunk_t data, chunk_t signature)
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{
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switch (scheme)
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{
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case SIGN_DEFAULT:
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/* default is EMSA-PKCS1 using SHA1 */
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case SIGN_RSA_EMSA_PKCS1_SHA1:
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return verify_emsa_pkcs1_signature(this, NID_sha1, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA256:
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return verify_emsa_pkcs1_signature(this, NID_sha256, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA384:
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return verify_emsa_pkcs1_signature(this, NID_sha384, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA512:
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return verify_emsa_pkcs1_signature(this, NID_sha512, data, signature);
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case SIGN_RSA_EMSA_PKCS1_MD5:
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return verify_emsa_pkcs1_signature(this, NID_md5, data, signature);
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default:
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DBG1("signature scheme %N not supported in RSA",
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signature_scheme_names, scheme);
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return FALSE;
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}
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}
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/**
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* Implementation of public_key_t.get_keysize.
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*/
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static bool encrypt(private_openssl_rsa_public_key_t *this, chunk_t crypto, chunk_t *plain)
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{
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DBG1("RSA public key encryption not implemented");
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return FALSE;
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}
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/**
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* Implementation of public_key_t.get_keysize.
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*/
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static size_t get_keysize(private_openssl_rsa_public_key_t *this)
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{
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return RSA_size(this->rsa);
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}
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/**
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* Implementation of public_key_t.get_id.
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*/
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static identification_t *get_id(private_openssl_rsa_public_key_t *this,
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id_type_t type)
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{
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switch (type)
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{
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case ID_PUBKEY_INFO_SHA1:
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return this->keyid_info;
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case ID_PUBKEY_SHA1:
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return this->keyid;
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default:
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return NULL;
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}
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}
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/**
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* Encodes the public key
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*/
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static chunk_t get_encoding_raw(RSA *rsa)
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{
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chunk_t enc = chunk_alloc(i2d_RSAPublicKey(rsa, NULL));
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u_char *p = enc.ptr;
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i2d_RSAPublicKey(rsa, &p);
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return enc;
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}
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/**
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* Encodes the public key with the algorithm used
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*/
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static chunk_t get_encoding_with_algo(RSA *rsa)
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{
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u_char *p;
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chunk_t enc;
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X509_PUBKEY *pubkey = X509_PUBKEY_new();
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ASN1_OBJECT_free(pubkey->algor->algorithm);
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pubkey->algor->algorithm = OBJ_nid2obj(NID_rsaEncryption);
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if (pubkey->algor->parameter == NULL ||
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pubkey->algor->parameter->type != V_ASN1_NULL)
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{
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ASN1_TYPE_free(pubkey->algor->parameter);
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pubkey->algor->parameter = ASN1_TYPE_new();
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pubkey->algor->parameter->type = V_ASN1_NULL;
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}
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enc = get_encoding_raw(rsa);
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M_ASN1_BIT_STRING_set(pubkey->public_key, enc.ptr, enc.len);
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chunk_free(&enc);
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enc = chunk_alloc(i2d_X509_PUBKEY(pubkey, NULL));
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p = enc.ptr;
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i2d_X509_PUBKEY(pubkey, &p);
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X509_PUBKEY_free(pubkey);
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return enc;
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}
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/*
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* Implementation of public_key_t.get_encoding.
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*/
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static chunk_t get_encoding(private_openssl_rsa_public_key_t *this)
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{
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return get_encoding_raw(this->rsa);
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}
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/**
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* Implementation of public_key_t.get_ref.
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*/
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static private_openssl_rsa_public_key_t* get_ref(private_openssl_rsa_public_key_t *this)
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{
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ref_get(&this->ref);
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return this;
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}
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/**
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* Implementation of openssl_rsa_public_key.destroy.
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*/
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static void destroy(private_openssl_rsa_public_key_t *this)
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{
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if (ref_put(&this->ref))
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{
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if (this->rsa)
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{
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RSA_free(this->rsa);
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}
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DESTROY_IF(this->keyid);
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DESTROY_IF(this->keyid_info);
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free(this);
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}
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}
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/**
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* Generic private constructor
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*/
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static private_openssl_rsa_public_key_t *openssl_rsa_public_key_create_empty()
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{
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private_openssl_rsa_public_key_t *this = malloc_thing(private_openssl_rsa_public_key_t);
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this->public.interface.get_type = (key_type_t (*)(public_key_t *this))get_type;
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this->public.interface.verify = (bool (*)(public_key_t *this, signature_scheme_t scheme, chunk_t data, chunk_t signature))verify;
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this->public.interface.encrypt = (bool (*)(public_key_t *this, chunk_t crypto, chunk_t *plain))encrypt;
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this->public.interface.get_keysize = (size_t (*) (public_key_t *this))get_keysize;
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this->public.interface.get_id = (identification_t* (*) (public_key_t *this,id_type_t))get_id;
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this->public.interface.get_encoding = (chunk_t(*)(public_key_t*))get_encoding;
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this->public.interface.get_ref = (public_key_t* (*)(public_key_t *this))get_ref;
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this->public.interface.destroy = (void (*)(public_key_t *this))destroy;
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this->keyid = NULL;
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this->keyid_info = NULL;
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this->ref = 1;
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return this;
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}
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/**
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* Build the RSA key identifier from n and e using SHA1 hashed publicKey(Info).
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* Also used in openssl_rsa_private_key.c.
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*/
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bool openssl_rsa_public_key_build_id(RSA *rsa, identification_t **keyid,
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identification_t **keyid_info)
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{
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chunk_t publicKeyInfo, publicKey, hash;
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hasher_t *hasher;
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hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
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if (hasher == NULL)
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{
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DBG1("SHA1 hash algorithm not supported, unable to use RSA");
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return FALSE;
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}
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publicKey = get_encoding_raw(rsa);
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hasher->allocate_hash(hasher, publicKey, &hash);
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*keyid = identification_create_from_encoding(ID_PUBKEY_SHA1, hash);
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chunk_free(&hash);
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publicKeyInfo = get_encoding_with_algo(rsa);
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hasher->allocate_hash(hasher, publicKeyInfo, &hash);
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*keyid_info = identification_create_from_encoding(ID_PUBKEY_INFO_SHA1, hash);
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chunk_free(&hash);
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hasher->destroy(hasher);
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chunk_free(&publicKeyInfo);
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chunk_free(&publicKey);
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return TRUE;
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}
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/**
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* Create a public key from BIGNUM values, used in openssl_rsa_private_key.c
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*/
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openssl_rsa_public_key_t *openssl_rsa_public_key_create_from_n_e(BIGNUM *n, BIGNUM *e)
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{
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private_openssl_rsa_public_key_t *this = openssl_rsa_public_key_create_empty();
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this->rsa = RSA_new();
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this->rsa->n = BN_dup(n);
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this->rsa->e = BN_dup(e);
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if (!openssl_rsa_public_key_build_id(this->rsa, &this->keyid, &this->keyid_info))
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{
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destroy(this);
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return NULL;
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}
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return &this->public;
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}
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/**
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* Load a public key from an ASN1 encoded blob
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*/
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static openssl_rsa_public_key_t *load(chunk_t blob)
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{
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u_char *p = blob.ptr;
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private_openssl_rsa_public_key_t *this = openssl_rsa_public_key_create_empty();
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this->rsa = d2i_RSAPublicKey(NULL, (const u_char**)&p, blob.len);
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chunk_clear(&blob);
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if (!this->rsa)
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{
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destroy(this);
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return NULL;
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}
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if (!openssl_rsa_public_key_build_id(this->rsa, &this->keyid, &this->keyid_info))
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{
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destroy(this);
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return NULL;
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}
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return &this->public;
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}
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typedef struct private_builder_t private_builder_t;
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/**
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* Builder implementation for key loading
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*/
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struct private_builder_t {
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/** implements the builder interface */
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builder_t public;
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/** loaded public key */
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openssl_rsa_public_key_t *key;
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};
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/**
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* Implementation of builder_t.build
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*/
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static openssl_rsa_public_key_t *build(private_builder_t *this)
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{
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openssl_rsa_public_key_t *key = this->key;
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free(this);
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return key;
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}
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/**
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* Implementation of builder_t.add
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*/
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static void add(private_builder_t *this, builder_part_t part, ...)
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{
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va_list args;
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if (this->key)
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{
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DBG1("ignoring surplus build part %N", builder_part_names, part);
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return;
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}
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switch (part)
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{
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case BUILD_BLOB_ASN1_DER:
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{
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va_start(args, part);
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this->key = load(va_arg(args, chunk_t));
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va_end(args);
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break;
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}
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default:
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DBG1("ignoring unsupported build part %N", builder_part_names, part);
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break;
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}
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}
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/**
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* Builder construction function
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*/
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builder_t *openssl_rsa_public_key_builder(key_type_t type)
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{
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private_builder_t *this;
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if (type != KEY_RSA)
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{
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return NULL;
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}
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this = malloc_thing(private_builder_t);
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this->key = NULL;
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this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add;
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this->public.build = (void*(*)(builder_t *this))build;
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return &this->public;
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}
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Reference in New Issue
Block a user