168 lines
7.4 KiB
C
168 lines
7.4 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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#include "tomcrypt_private.h"
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#if defined(LTC_MECC) && defined(LTC_DER)
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/**
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Export an ECC key as a binary packet
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@param out [out] Destination for the key
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@param outlen [in/out] Max size and resulting size of the exported key
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@param type The type of key you want to export (PK_PRIVATE or PK_PUBLIC)
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@param key The key to export
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@return CRYPT_OK if successful
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*/
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int ecc_export_openssl(unsigned char *out, unsigned long *outlen, int type, const ecc_key *key)
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{
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int err;
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void *prime, *order, *a, *b, *gx, *gy;
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unsigned char bin_a[256], bin_b[256], bin_k[256], bin_g[512], bin_xy[512];
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unsigned long len_a, len_b, len_k, len_g, len_xy;
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unsigned long cofactor, one = 1;
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const char *OID;
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unsigned long oid[16], oidlen;
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ltc_asn1_list seq_fieldid[2], seq_curve[2], seq_ecparams[6], seq_priv[4], pub_xy, ecparams;
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int flag_oid = type & PK_CURVEOID ? 1 : 0;
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int flag_com = type & PK_COMPRESSED ? 1 : 0;
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int flag_pri = type & PK_PRIVATE ? 1 : 0;
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LTC_ARGCHK(out != NULL);
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LTC_ARGCHK(outlen != NULL);
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LTC_ARGCHK(key != NULL);
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if (key->type != PK_PRIVATE && flag_pri) return CRYPT_PK_TYPE_MISMATCH;
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if (flag_oid) {
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/* http://tools.ietf.org/html/rfc5912
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ECParameters ::= CHOICE {
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namedCurve CURVE.&id({NamedCurve}) # OBJECT
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}
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*/
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if (key->dp.oidlen == 0) { err = CRYPT_INVALID_ARG; goto error; }
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LTC_SET_ASN1(&ecparams, 0, LTC_ASN1_OBJECT_IDENTIFIER, key->dp.oid, key->dp.oidlen);
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}
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else {
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prime = key->dp.prime;
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order = key->dp.order;
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a = key->dp.A;
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b = key->dp.B;
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gx = key->dp.base.x;
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gy = key->dp.base.y;
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cofactor = key->dp.cofactor;
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/* curve param a */
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len_a = ltc_mp_unsigned_bin_size(a);
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if (len_a > sizeof(bin_a)) { err = CRYPT_BUFFER_OVERFLOW; goto error; }
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if ((err = ltc_mp_to_unsigned_bin(a, bin_a)) != CRYPT_OK) { goto error; }
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if (len_a == 0) { len_a = 1; bin_a[0] = 0; } /* handle case a == 0 */
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/* curve param b */
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len_b = ltc_mp_unsigned_bin_size(b);
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if (len_b > sizeof(bin_b)) { err = CRYPT_BUFFER_OVERFLOW; goto error; }
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if ((err = ltc_mp_to_unsigned_bin(b, bin_b)) != CRYPT_OK) { goto error; }
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if (len_b == 0) { len_b = 1; bin_b[0] = 0; } /* handle case b == 0 */
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/* base point - (un)compressed based on flag_com */
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len_g = sizeof(bin_g);
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err = ltc_ecc_export_point(bin_g, &len_g, gx, gy, key->dp.size, flag_com);
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if (err != CRYPT_OK) { goto error; }
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/* we support only prime-field EC */
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if ((err = pk_get_oid(LTC_OID_EC_PRIMEF, &OID)) != CRYPT_OK) { goto error; }
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/* http://tools.ietf.org/html/rfc3279
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ECParameters ::= SEQUENCE { # SEQUENCE
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version INTEGER { ecpVer1(1) } (ecpVer1) # INTEGER :01
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FieldID ::= SEQUENCE { # SEQUENCE
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fieldType FIELD-ID.&id({IOSet}), # OBJECT :prime-field
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parameters FIELD-ID.&Type({IOSet}{@fieldType}) # INTEGER
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}
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Curve ::= SEQUENCE { # SEQUENCE
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a FieldElement ::= OCTET STRING # OCTET STRING
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b FieldElement ::= OCTET STRING # OCTET STRING
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seed BIT STRING OPTIONAL
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}
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base ECPoint ::= OCTET STRING # OCTET STRING
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order INTEGER, # INTEGER
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cofactor INTEGER OPTIONAL # INTEGER
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}
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*/
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oidlen = LTC_ARRAY_SIZE(oid);
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if ((err = pk_oid_str_to_num(OID, oid, &oidlen)) != CRYPT_OK) {
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goto error;
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}
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/* FieldID SEQUENCE */
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LTC_SET_ASN1(seq_fieldid, 0, LTC_ASN1_OBJECT_IDENTIFIER, oid, oidlen);
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LTC_SET_ASN1(seq_fieldid, 1, LTC_ASN1_INTEGER, prime, 1UL);
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/* Curve SEQUENCE */
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LTC_SET_ASN1(seq_curve, 0, LTC_ASN1_OCTET_STRING, bin_a, len_a);
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LTC_SET_ASN1(seq_curve, 1, LTC_ASN1_OCTET_STRING, bin_b, len_b);
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/* ECParameters SEQUENCE */
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LTC_SET_ASN1(seq_ecparams, 0, LTC_ASN1_SHORT_INTEGER, &one, 1UL);
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LTC_SET_ASN1(seq_ecparams, 1, LTC_ASN1_SEQUENCE, seq_fieldid, 2UL);
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LTC_SET_ASN1(seq_ecparams, 2, LTC_ASN1_SEQUENCE, seq_curve, 2UL);
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LTC_SET_ASN1(seq_ecparams, 3, LTC_ASN1_OCTET_STRING, bin_g, len_g);
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LTC_SET_ASN1(seq_ecparams, 4, LTC_ASN1_INTEGER, order, 1UL);
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LTC_SET_ASN1(seq_ecparams, 5, LTC_ASN1_SHORT_INTEGER, &cofactor, 1UL);
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/* ECParameters used by ECPrivateKey or SubjectPublicKeyInfo below */
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LTC_SET_ASN1(&ecparams, 0, LTC_ASN1_SEQUENCE, seq_ecparams, 6UL);
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}
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/* public key - (un)compressed based on flag_com */
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len_xy = sizeof(bin_xy);
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err = ltc_ecc_export_point(bin_xy, &len_xy, key->pubkey.x, key->pubkey.y, key->dp.size, flag_com);
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if (err != CRYPT_OK) {
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goto error;
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}
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if (flag_pri) {
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/* http://tools.ietf.org/html/rfc5915
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ECPrivateKey ::= SEQUENCE { # SEQUENCE
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version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1) # INTEGER :01
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privateKey OCTET STRING, # OCTET STRING
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[0] ECParameters # see above
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[1] publicKey # BIT STRING
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}
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*/
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/* private key */
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len_k = ltc_mp_unsigned_bin_size(key->k);
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if (len_k > sizeof(bin_k)) { err = CRYPT_BUFFER_OVERFLOW; goto error; }
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if ((err = ltc_mp_to_unsigned_bin(key->k, bin_k)) != CRYPT_OK) { goto error; }
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LTC_SET_ASN1(&pub_xy, 0, LTC_ASN1_RAW_BIT_STRING, bin_xy, 8*len_xy);
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LTC_SET_ASN1(seq_priv, 0, LTC_ASN1_SHORT_INTEGER, &one, 1);
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LTC_SET_ASN1(seq_priv, 1, LTC_ASN1_OCTET_STRING, bin_k, len_k);
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LTC_SET_ASN1_CUSTOM_CONSTRUCTED(seq_priv, 2, LTC_ASN1_CL_CONTEXT_SPECIFIC, 0, &ecparams); /* context specific 0 */
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LTC_SET_ASN1_CUSTOM_CONSTRUCTED(seq_priv, 3, LTC_ASN1_CL_CONTEXT_SPECIFIC, 1, &pub_xy); /* context specific 1 */
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err = der_encode_sequence(seq_priv, 4, out, outlen);
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}
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else {
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/* http://tools.ietf.org/html/rfc5480
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SubjectPublicKeyInfo ::= SEQUENCE { # SEQUENCE
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AlgorithmIdentifier ::= SEQUENCE { # SEQUENCE
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algorithm OBJECT IDENTIFIER # OBJECT :id-ecPublicKey
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ECParameters # see above
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}
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subjectPublicKey BIT STRING # BIT STRING
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}
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*/
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err = x509_encode_subject_public_key_info( out, outlen, LTC_OID_EC, bin_xy, len_xy,
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ecparams.type, ecparams.data, ecparams.size );
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}
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error:
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return err;
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}
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#endif
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